GRDC GrowNotes Northern Maize December 2014

MAIZE -

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December 2014

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planning/paddock preparation • pre-planting • planting •

plant growth and physiology • nutrition and fertiliser • weed control •

insect control • nematode control • diseases • plant growth regulators

and canopy management • crop desiccation and spray out • harvest •

storage • environmental issues • marketing • current research

December 2014

Maize

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Table of Contents

A Introduction

A.1 Management at a glance .................................................................................. ix

A.1.1 Profitability............................................................................................... x

A.2 Crop overview .................................................................................................. xi

A.2.1 Production ............................................................................................ xiii

A.3 Maizetypes .....................................................................................................xiv

A.3.1 Maizeforprocessing ............................................................................xvi

A.3.2 Maizeforstockfeed ..............................................................................xvi

A.4 Keywords ........................................................................................................xvi

1 Planning/Paddock preparation

1.1 Paddockselection .............................................................................................2

1.1.1 Soiltypes ................................................................................................2

1.2 Paddockrotationandhistory.............................................................................4

1.3 Maizeincroprotations ......................................................................................4

1.3.2 Inrotationwithcotton..............................................................................5

1.3.1 Inrotationwithcotton..............................................................................5

1.3.3 Pestanddiseaseimpacts .......................................................................6

1.4 Fallow weed control ..........................................................................................6

1.5 Seedbedrequirements ......................................................................................7

1.6 Soilmoisture .....................................................................................................8

1.6.1 Waterrequirements .................................................................................8

1.6.2 Cropwateruse .......................................................................................9

1.6.3 ModificationofagronomytoimproveWUE ............................................10

Planting date ............................................................................................................. 10

Planting geometry ..................................................................................................... 10

Tillage ....................................................................................................................... 10

Residue retention and plastic mulch .......................................................................... 11

Weed control and fertiliser use .................................................................................. 11

Irrigation management............................................................................................... 11

1.6.4 Irrigation ................................................................................................12

Water budgeting........................................................................................................ 13

Peak water use ......................................................................................................... 14

Scheduling irrigations ................................................................................................ 14

Timing the first irrigation ............................................................................................ 15

Irrigation scheduling .................................................................................................. 15

Timing the last irrigation............................................................................................. 16

Scheduling supplementary irrigation ......................................................................... 17

1.7 Optimisingmaizeyieldunderirrigation .............................................................18

1.7.1 Howmuchwaterisneededtooptimisemaizeyield? .............................19

1.7.2 Some local data ....................................................................................23

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1.7.3 IrrigationinQueensland .........................................................................24

1.8 Yieldandtargets .............................................................................................24

1.8.1 Seasonaloutlook...................................................................................26

1.8.2 Wateruseefficiency ..............................................................................27

1.8.3 Nitrogen-useefficiency ..........................................................................29

1.8.4 Double-cropoptions .............................................................................30

1.8.5 Whatisrelaycropping? .........................................................................31

1.9 Relaycroppingextendscroppingwindow .......................................................32

1.9.1 Keypoints .............................................................................................32

Could the relay-cropping systems from the Argentine Pampas open a new frontier for

the northern grains industry? ..................................................................................... 32

1.9.2 Constraints............................................................................................33

1.9.3 Opportunity ...........................................................................................34

1.10 Nematodestatusofpaddock ..........................................................................34

1.10.1 Nematodetestingofsoil ........................................................................34

1.10.2 Effectsofcroppinghistoryonnematodestatus .....................................35

1.11 Insectstatusofpaddock .................................................................................36

1.11.1 Soilsamplingforinsects ........................................................................36

Soil sampling by spade ............................................................................................. 37

Germinating-seed bait technique ............................................................................... 37

Detecting soil-dwelling insects ................................................................................... 38

2 Pre-planting

2.1 Selectingmaizevarieties ...................................................................................1

2.2 Maizevarietycharacteristics ..............................................................................2

2.2.1 Maturity ...................................................................................................3

2.2.2 Timetoflowering .....................................................................................3

2.2.3 Adaptability .............................................................................................4

2.2.4 Cobheight ..............................................................................................4

2.2.5 Huskcover ..............................................................................................4

2.2.6 Standability .............................................................................................5

2.2.7 Enduse...................................................................................................5

2.2.8 Isolation ..................................................................................................5

2.2.9 Tillers ......................................................................................................5

2.2.10 Thefinaldecision—whichvariety? ...........................................................6

2.3 Plantingseedquality .........................................................................................6

2.3.1 Seedsize ................................................................................................6

2.3.2 Saferatesoffertilisersownwiththeseed ................................................7

3 Planting

3.1 Seedtreatments ................................................................................................1

3.2 Soiltype ............................................................................................................1


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3.3 Timeofsowing ..................................................................................................2

3.3.1 Soil temperature ......................................................................................2

3.3.2 Plantingmoisturerequirement .................................................................4

3.3.3 NewSouthWales ....................................................................................4

3.3.4 Queensland .............................................................................................5

3.4 Targeted plant population ..................................................................................5

3.4.1 Plantpopulations ....................................................................................6

3.4.2 Planting rate ............................................................................................8

3.4.3 Rowspacing ...........................................................................................9

3.5 Sowingdepth ..................................................................................................10

3.6 Sowing equipment ..........................................................................................10

3.6.1 Evennessofestablishment ....................................................................11

4 Plant growth and physiology

4.1 Germination and emergence .............................................................................2

4.1.1 Germination—VEstage ...........................................................................2

4.1.2 Emergence—VEstage ............................................................................4

4.1.3 Factorsaffectinggerminationandemergence .........................................5

Moisture ...................................................................................................................... 5

Waterlogging ............................................................................................................... 5

Temperature ................................................................................................................ 5

Oxygen ....................................................................................................................... 7

Nutrition ...................................................................................................................... 7

Seedbed ..................................................................................................................... 8

Sowing depth .............................................................................................................. 8

Plant population .......................................................................................................... 9

4.2 Vegetativegrowth ............................................................................................11

4.2.1 VegetativeGrowth .................................................................................11

V1–V2 stage .............................................................................................................. 11

V3–V5 stages ............................................................................................................ 11

Ear initiation ............................................................................................................... 12

Establishing the number of kernel rows around the ear (V5–V8 stage) ....................... 13

V6 and V7 stages ...................................................................................................... 13

Establishing kernel numbers (V7–pollination) .............................................................. 14

V8 and V9 stages ...................................................................................................... 15

V10 and V11 stages .................................................................................................. 16

V12 and V13 stages .................................................................................................. 16

V14 and V15 stages .................................................................................................. 18

V16 and V17 stages .................................................................................................. 18

V18 or VT stage ........................................................................................................ 19

4.2.2 Factorsaffectingvegetativegrowth .......................................................19

Moisture .................................................................................................................... 19

Irrigation .................................................................................................................... 21

Nutrition .................................................................................................................... 23


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4.3 Reproductive development ..............................................................................27

4.3.1 Stages ..................................................................................................27

Tasselling–VT............................................................................................................. 27

Flowering (pollen shed and silking)–R1 ...................................................................... 28

4.3.2 Factorsaffectingreproductivedevelopment ..........................................30

Moisture stress .......................................................................................................... 30

Temperature .............................................................................................................. 32

Assimilate supply....................................................................................................... 33

Competition from other plant parts ............................................................................ 33

4.4 Kernel development ........................................................................................34

4.4.1 Stages ..................................................................................................34

R2 (blister stage) ....................................................................................................... 34

R3 (milk stage) .......................................................................................................... 35

R4 (dough stage)....................................................................................................... 35

R5 (dent stage).......................................................................................................... 36

4.4.2 Maturityanddrying ...............................................................................36

Stage R6 (physiological maturity) ............................................................................... 36

Factors affecting kernel development ........................................................................ 37

Moisture stress .......................................................................................................... 39

4.4.3 Referencesandfurtherreading .............................................................40

5 Nutrition and fertiliser

5.1 Soilfertility .........................................................................................................3

5.2 Soiltesting ........................................................................................................5

5.3 Keynutrients .....................................................................................................6

5.4 Animal manure ..................................................................................................8

5.5 Cropremovalrates ............................................................................................9

5.6 Nitrogen ...........................................................................................................9

5.7 Phosphorus ...................................................................................................11

5.8 Sulfur .............................................................................................................13

5.9 Potassium .......................................................................................................13

5.10 Long-fallowdisorder ........................................................................................15

5.11 Micronutrients .................................................................................................16

5.11.1 Zinc .......................................................................................................16

5.11.2 Molybdenum .........................................................................................17

5.11.3 Magnesium(Mg) ...................................................................................18

6 Weed control

6.1 Competitionfromweeds ...................................................................................2

6.2 Mainweedspeciesofconcerninmaizecrops ..................................................2

6.3 Formsofweedcontrol ......................................................................................5

6.3.1 Mechanicalweedcontrol .........................................................................5

6.3.2 Mechanicalandchemicalweedcontrol ...................................................6


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6.3.3 Chemicalweedcontrol ............................................................................6

6.4 Farmhygiene ....................................................................................................6

6.5 Crop rotation .....................................................................................................6

6.6 Maizegrowthstages .........................................................................................7

6.7 Pre-emergentherbicides ...................................................................................7

6.8 Post-plantpre-emergentherbicides ..................................................................9

6.8.1 Imidiazolinonetechnology .......................................................................9

6.9 Potentialherbicidedamageeffect....................................................................10

7 Insect control

7.1 Maizepestsbycropstage ................................................................................2

7.2 Earlypests ........................................................................................................2

7.2.1 Mice ........................................................................................................3

7.3 Soilinsects ........................................................................................................3

7.3.1 Monitoringforsoilinsects ........................................................................4

7.3.2 Blackfieldearwig ....................................................................................5

7.3.3 True wireworm ........................................................................................6

7.3.4 Falsewireworm .......................................................................................6

7.3.5 Cutworm .................................................................................................7

7.3.6 Whitegrubs.............................................................................................8

7.4 Pestsofthevegetativestage .............................................................................9

7.4.1 Maizeleafhoppers ...................................................................................9

7.4.2 Maizethrips.........................................................................................10

7.4.3 Cornaphid ..........................................................................................10

7.4.4 Podsuckingorshieldbugs ....................................................................12

7.4.5 Locusts .................................................................................................13

Whitefringed weevil ................................................................................................... 13

7.4.6 Redshoulderedleafbeetle .....................................................................13

7.4.7 Swarmingleafbeetles ...........................................................................14

7.4.8 Armyworms ...........................................................................................14

7.5 Silking–tasseling-stagepests...........................................................................15

7.5.1 Corn earworm .......................................................................................15

7.6 Pestsofthegrainfillstage ................................................................................17

7.6.1 Two-spottedmite ..................................................................................17

7.6.2 Yellowpeachmoth ...............................................................................17

8 Nematode management

8.1 Nematodetestingofsoil ....................................................................................1

8.2 Effectsofcroppinghistoryonnematodestatus .................................................2

8.3 Usingrotationsincludingmaizetomanagenematodes .....................................3

8.3.1 Keypoints: ..............................................................................................3


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9 Diseases

9.1 Diseasesofadevelopingandmaturemaizeplant .............................................2

9.1.1 Seedrotsandseedlingblights ...............................................................2

9.1.2 Stalkandrootrotdiseases ......................................................................2

Fusarium stalk rot (caused by Fusarium verticillioides [Gibberella fujikuroi] and other

Fusarium species) ....................................................................................................... 3

Gibberella stalk rot (caused by Gibberella zeae; Fusarium graminearum) ..................... 4

9.1.3 Earandkernelrots ..................................................................................4

Fusarium cob rot or ear rot (Fusarium verticillioides and other Fusarium species) ......... 5

Gibberella cob rot, ear rot or pink ear rot (caused by Gibberella zeae; Fusarium

graminearum) .............................................................................................................. 5

Diplodia cob rot or ear rot (caused by Diplodia spp.) ................................................... 5

9.1.4 Blights .....................................................................................................6

Turcica leaf blight or turcicum leaf blight (caused by Exserohilum turcicum) ................. 6

Maydis leaf blight (caused by Bipolaris maydis) ........................................................... 7

9.2 Rusts ................................................................................................................7

9.2.1 Commonrust(causedbyPuccinia sorghi)...............................................7

9.2.2 Polysorarustortropicalrustorsouthernmaizerust(causedbyPuccinia

polysora) ..............................................................................................................8

9.3 Smuts ...............................................................................................................8

9.3.1 Boilsmutorcommonsmut(causedbyUstilago zeae,formerlyknownas

U. maydis) ............................................................................................................8

9.3.2 Headsmut(causedbySporisorium reilianum) .........................................9

9.4 Wallabyear .......................................................................................................9

9.5 Viruses ............................................................................................................10

9.5.1 Johnson grass mosaic virus ..................................................................10

9.5.2 Maize dwarf mosaic virus .....................................................................10

9.6 Rotsofstoredgrain .........................................................................................11

9.7 Mycotoxinsandmycotoxicoses ..............................................................................11

10 Plant growth regulators and canopy management

11 Crop desiccation/spray out

12 Harvest

12.1 Timing ..............................................................................................................1

12.2 Grainformillingmarkets ...................................................................................2

12.3 Blacklayerorphysiologicalmaturity ..................................................................3

13 Storage

13.1 Graininsecticides ..............................................................................................2

13.2 Howtostoremaizeon-farm ..............................................................................3

13.3 Hygiene .............................................................................................................6


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13.4 Grainprotectantsandfumigants .......................................................................7

13.5 Aerationduringstorage ...................................................................................11

13.6 Monitoring grain ..............................................................................................14

14 Environmental issues

14.1 Frostissues ......................................................................................................1

14.1.1 Conditionscausingfrostdamage ............................................................1

14.1.2 Assessingfrostdamage ..........................................................................2

14.1.3 Reducingtheriskoffrostdamage ...........................................................3

14.2 Waterloggingandfloodingissues .....................................................................3

14.2.1 Effectsonthemaizerootsystem .............................................................4

15 Marketing

15.1 Preventingmycotoxincontamination ................................................................2

15.2 Marketing .........................................................................................................2

15.2.1 Grain .......................................................................................................2

15.2.2 Marketingsilage ......................................................................................2

15.2.3 Dryingcornforthegrittingmillers ............................................................3

15.3 MaizeAssociationofAustralia(MAA) .................................................................3

16 Current research

17 Key contacts

18 References


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FeedbackTable of Contents Section A MAIZE - Introduction

SECTIONA

Introduction

A.1 Management at a glance

Organisemarketingcontractsbeforeplanting.Growersshoulddiscussspecificquality

requirementswithenduserswhennegotiatingcontracts(Figure1).Marketsectorsfor

humanconsumptionhavestrictspecifications.Neworprospectivegrowersshouldusethe

MaizeAssociationofAustraliawebsitetoconnectwithbuyerslookingformaize.Growers

shouldbeawarethat,onoccasion,onlyspecificvarietiesarecontracted;therefore,conflicts

mayarisewithregardtovarietalchoiceandagronomicperformance.

• Planthybridsthathavethedesiredcharacteristicsforyourconditions.

• Plantattheoptimumtimetoavoidearlyfrosts,extremeheatatflowering,andacool,

slowdry-down.

• Setatargetyieldbasedonmoistureavailabilityandmatchinputstothetarget.Maizeis

lesstolerantofmoisturestressthanothersummercropssuchasgrainsorghum.

• Plantinlanddrylandcropswhenthereisatleast1mdepthofwetsoil.

• Forirrigatedcrops,calculatewaterbudgets,matchingthecropareatowater

allocation.Donotstretchirrigationintervalsinordertoincreasecroparea,inparticular

fromjustpriortotassellingtothestartofthemilk-linestage.

• Alwaysusepress-wheelsatplanting.

• Adjustplantpopulationandrowspacingaccordingtothetargetyield.

• Applynitrogen,phosphorusandpotassiumfertiliserbasedontargetyields,soiltests

and/orpreviouscropyields.

• Usecontrolled-trafficfarmingwithno-tilltoreducesoilcompaction(maizeisrelatively

susceptibletocompaction),improvemoisturestorageandreducefuelcosts.1

• Planandimplementaneffectiveweedmanagementstrategypriortoplanting.

• Longfallowdisorderinmaizecanseverelylimitthecrop.

1 NMoore,LSerafin,LJenkins(2014)Summercropproductionguide2014.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/agriculture/broadacre/guides/summer-crop-production-guide

i More information

MaizeAssociationof

Australia


http://www.maizeaustralia.com.au/

http://www.dpi.nsw.gov.au/agriculture/broadacre/guides/summer-crop-production-guide



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Figure 1: Organise marketing contracts before planting to ensure that specifications are met for human consumption market sectors.

A.1.1 ProfitabilityManygrowersassumethatthehighestyieldingcropsarethemostprofitable.Thereis

aperceptionthatincreasinginputssuchasfertiliserandwaterwillautomaticallyleadto

greateryieldsand,hence,moreprofitperhectare.

However,increasinginputstomaximumlevelsdoesnotalwaysleadtogreateryieldsand

abetterprofitmargin.Thehighestyielding,competition-winningcropmayattractalotof

interestbutitmaynotbeasprofitableasaloweryieldingcropthatiswellmanaged.

Rapidadvancesinplantbreedingtechnology,plantprotectionandmanagementexpertise

overthelastdecadehaveresultedinsignificantincreasesintheyieldpotentialandstress

toleranceofmaize.Formanyfarmersproducingmaizeasagraincroporforsilage

production,potentialexiststoincreaseprofits.Severalimportantfactorswillcontributeto

this.Forirrigationfarmers,watermanagementiskey.

Theyieldpotentialofmaizewillvaryamongdistrictsandfarmsbecauseofwateravailability,

altitude,sunlight,soilstructureandsoilfertility.Yieldpotentialwillalsovarybetween

seasonsatthesamesitedependingonseasonalconditions(e.g.heatwave,drought)as

wellaschoiceofhybridandsowingtime.

Themostprofitablemaizecropisobtainedbyoptimising(ratherthanmaximising)key

inputssuchasseed,fertiliserandwater,andthetimingoftheseinputsasshowninFigure

2.

Manyfarmersunderestimatetheeffectofyieldonprofit,equatinga10%increaseinyield

witha10%increaseinprofit.Therealincreaseinprofitmaybe50%oreven100%.Thisis

becausemanycosts,suchascultivation,plantingandsprayingremainthesameforallyield

levels.

Section A MAIZE - Introduction


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Importantstepstowardsaprofitablemaizecropare:

• determiningthemarketyouintendtosupply

• understandingtherequirementsofthecrop

• settingayieldgoalforeachfield

• plantingsuitablehybridsatthecorrectplantpopulations

• providingadequatefertiliserandwateratthecriticalgrowingstages

• growingonlyanareayoucanmanage2

Figure 2:

Yield Level

“Variable costs” to grow extra high yields(more fertiliser, better weed and insect control, etc.)

LOSS

PROFIT

Yield in $ Per Acre

Cost to Grow

“Fixed costs” stay about the same regardless of yield (interest, taxes, machinery, ploughing, harrowing, cultivating, harvesting, selling)

LOSS

“Contest Winning”Very HighHighAverage

Timing of key inputs for growing a profitable crop. (Source: Pioneer)

A.2 Crop overview

Maizeisamultipurpose,summer,cereal,grainandsilagecropthatservesasagood

rotationcropwithlegumesandcotton.Maizehasalowcapitalinvestment,lowgrowing

riskandgenerallyalongerwindowofharvestthanothercrops.Theindustryisvaluedat

AU$25–35millionannually,dependingonprices,areaplantedandyields.3

InAustraliamaizeisaminorsummercropwithanannualproductionof350,000–450,000

tonnes(t),historicallymostofwhichisconsumeddomestically(Figure3).However,with

thehelpoftheMaizeAssociationofAustralia,thepeakbodyrepresentingAustralianmaize

growersandtheindustryatlarge,anewexportmarkethasbeenopeneduptofarmers

andtraders.MaizeproducedinAustraliaisapproximately50%rainfedordrylandand50%

grownwiththeassistanceofirrigation.AllAustralianmaizeisnon-geneticallymodified

organism(non-GMO).

Maizegrainvariesgreatlyfromverysoft(starchy)toveryhard(hardendosperm),which

determinesenduse.

2 PioneerHi-BredAustralia.Growthpotential.CornGrowers’Workshop.http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Corn_Workshop_Book.pdf

3 DAFF(2012)MaizeproductioninQueensland.DepartmentofAgriculture,FisheriesandForestryQueensland.http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize

i More information

Growthpotential.Corn

Growers’Workshop.

Pioneer Hi-Bred

Australia.

i More information

MaizeAssociationof

Australia

Commoditygrowing

guides—sweetcorn.

NSW Department of

PrimaryIndustries.

Australianmaizeindustry

overview—2012.

GrainsResearch

and Development

Corporation.



http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Corn_Workshop_Book.pdf


http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize







http://www.dpi.nsw.gov.au/agriculture/horticulture/vegetables/commodity/sweet-corn




http://grdc.com.au/Research-and-Development/GRDC-Update-Papers/2012/08/Australian-maize-industry-overview-2012





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Figure 3: Australia is developing export markets for maize. (Photo: Pacific Seeds)

‘Flintcorn’(Zea mays var. indurate,alsoknownasIndiancornorcalicocorn)isavariant

ofmaize(Zea maysL.).Becauseeachkernelhasahardouterlayertoprotectthesoft

endosperm,itislikenedtobeing‘ashardasflint’.4

‘Dentcorn’(var.indentata)alsoknownas‘yellowdentcorn’,‘Reid’syellowdentcorn’,

‘whitedentcorn’or‘fieldcorn’isavarietyofmaizewithahighsoft-starchcontent.It

receiveditsnamebecauseofthesmallindentation(‘dent’)atthecrownofeachkernelona

ripe ear of corn. 5

Grownunderthesameconditions,thehighestproteinwouldbeexpectedinquickflint,

followedbymed-slowflint,quickdentandthelowestinmed-slowdent(Table1).6

Twotypesofstarchcanbecontainedinmaize.Regularyellowmaizeandwhitemaize

containapproximately73%amylopectinand27%amylose.Waxymaizeproduces100%

amylopectin.Hi-amylosecanbeupto80–90%amyloseand10–20%amylopectin.

Theindustrydeliverystandardandasafestoragelevelis14%moisturecontent.7

4 Flintcorn.Wikipedia,http://en.wikipedia.org/wiki/Flint_corn

5 Dentcorn.Wikipedia,http://en.wikipedia.org/wiki/Dent_corn

6 PacificSeeds(2008/2009)Hybridcornagronomyguide2008/09,PacificSeedsPtyLtd,http://cairo.directrouter.com/~pacseeds/images/stories/corn/information/cornagronomy08.pdf


i More information

Harvestingand

productionofsweet

corn.Industryoverview.

Department of

Agriculture,Fisheriesand

ForestryQueensland.



http://en.wikipedia.org/wiki/Maize

http://en.wikipedia.org/wiki/Endosperm

http://en.wikipedia.org/wiki/Flint

http://en.wikipedia.org/wiki/Maize

http://en.wikipedia.org/wiki/Starch

http://en.wikipedia.org/wiki/Corn_kernel

http://en.wikipedia.org/wiki/Ripeness

http://en.wikipedia.org/wiki/Flint_corn

http://en.wikipedia.org/wiki/Dent_corn

http://cairo.directrouter.com/~pacseeds/images/stories/corn/information/cornagronomy08.pdf




https://www.daff.qld.gov.au/plants/fruit-and-vegetables/vegetables/sweet-corn/harvesting-sweet-corn






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Table 1: Typical analysis of flint and dent types on a dry basis

Source:PacificSeeds

Flint DentStarchcontent(%) 66.5 72.0

Proteincontent(%) 13.5 10.0

Oilcontent(%) 6.0 5.0

Fibrecontent(%) 14.0 143.0

Maizeisthethirdmostimportantcerealcropspeciesintheworld(afterwheatandrice)

andisgrownacrossawiderangeofclimates,butmainlyinthewarmertemperateregions

andhumidsubtropics.Maizehasmultipleuses,includinghumanfoods,animalfeeds,and

themanufactureofpharmaceuticalandindustrialproducts.Itisthestaplefoodsourcefor

peopleinmanycountries.Maizeishighlydesirableasananimalfeedbecauseofthehigh

energyandfeedvalueofthekernel,leafandstem.Itisincreasinglyimportantinmany

countriesforindustrialandpharmaceuticalapplications.Itcanbeusedtoproducestarch,

ethanolandplasticsandasabaseforantibioticproduction.Overthepast40years,the

totalglobalareasowntomaizehasincreasedbyabout40%andproductionhasdoubled.

MaizeisaC4(tropical)plant.Itusescarbondioxide,solarradiation,waterandnitrogen

moreefficientlyduringphotosynthesisthanC3(temperate)crops.Thewater-use

efficiencyofmaizeisapproximatelydoublethatofC3cropsgrownatthesamesites.The

transpirationratioofmaize(moleculesofwaterlostpermoleculeofcarbondioxidefixed)is

388,whereasthatofwheatis613andsoybean704.MostplantsareC3plants,including

wheat,barleyandoats.

C4plantshaveaspecialisedtypeofphotosynthesiswherebycarbondioxideisfirst

incorporatedintoa4-carboncompound.C4plantscarryoutphotosynthesisfasterthanC3

plantsunderhighlightintensityandhightemperatures.Thisgivesbetterwater-use

efficiencythanthatofC3plantsatthesamelocation,becausethestomata(pores)are

openforashorterperiod.

A.2.1 ProductionTotalmaizeproductioninAustraliain2009was255,000t,coveringanareaof49,000ha.

Forproduction,thehistoricalhighwasin2002at454,000t,andforarea,itwasin1924at

172,000ha.Since1924,theareaundercultivationformaizehassteadilydeclined,whereas

productionincreasednotablyfromtheearly1980s(Figure4).8

8 AustralianBureauofStatistics(2013)HistoricalSelectedAgricultureCommodities,byState(1861toPresent),(cat.no.7124.0).AustralianBureauofStatistics,http://www.abs.gov.au/AUSSTATS/[email protected]/mf/7124.0

C3 plant. Hasanormaltypeofphotosynthesis:carbondioxideisfirstincorporatedintoa

3-carboncompound.MostplantsareC3plants.ExamplesofC3plantsarewheat,barley

andoats.

C4 plant. Hasaspecialisedtypeofphotosynthesis:carbondioxideisfirstincorporatedinto

a4-carboncompound.C4plantscarryoutphotosynthesisfasterthanC3plantsunderhigh

lightintensityandhightemperatures.Thisgivesbetterwater-useefficiencythanthatofC3

plantsatthesamelocation,becausethestomata(pores)areopenforashorterperiod.



http://www.abs.gov.au/AUSSTATS/[email protected]/mf/7124.0



xivKnow more. Grow more.

December 2014



Figure 4:

0

100000

1861 1876 1891 1906 1921 1936 1951 1966 1981 1996 2011

200000

300000

400000

500000

hect

ares

/ t

onn

es

year

production

area

Maize production and area in Australia. (Source: ABS)

TemperatureandavailablemoisturedeterminewheremaizeisgrowninNewSouthWales

(NSW).ProductionareasincludetheNorthCoast,LiverpoolPlains,andNorthwestSlopes

andPlains.Intheseareas,thecropgrowsbestindeep,well-drained,fertilesoils.

MaizeisgrownasadrylandcropinthenorthernpartsofNSWwherethereismorereliable

summerrainfall,whichgivesadequatesoilmoistureatplantingtime.Someofthesecrops

mayreceivesupplementaryirrigation.

TheaverageareaofmaizegrowninNSWfrom1998to2007was26,944ha,producing

211,681 t of grain. 9

In2012–13,34,000hawasplantedtomaizeforgraininNSW,producing261,232tatan

averageyieldof7.7t/ha.InQueenslandforthisperiod,40,208haproduced213,117tat

anaverageyieldof5.3t/ha.10Themainmaize-growingareasinQueenslandincludethe

DarlingDowns,CentralHighlandsandBurdekinIrrigationArea.

A.3 Maize types

AlmostallmaizeinNSWandQueenslandisproducedfromhybrids.Ahybridisacross

betweenstrainswithinasinglespecies.Incommercialhybridmaize,thesestrainsare

fixedinbredlines.Hybridsareproducedandselectedbecausetheyhavedesirable

characteristicsthataregreaterthanthoseoftheindividualparents.

ThecrossbetweentwodifferentinbredlinesproducesanF1hybrid(Figure5).Thishybrid

hastwoalleles(analleleisanalternativeformofagene),onecontributedbyeachparent.

Onealleleisusuallydominantandtheotherrecessive.TheF1generationindividualsareall

similar.

9 AustralianBureauofStatistics(2013)HistoricalSelectedAgricultureCommodities,byState(1861toPresent),(cat.no.7124.0).AustralianBureauofStatistics,http://www.abs.gov.au/AUSSTATS/[email protected]/mf/7124.0

10 AustralianBureauofStatistics(2014)7121.0-AgriculturalCommodities,Australiaand7503.0-ValueofAgriculturalCommoditiesProduced.AustralianBureauofStatistics,http://www.abs.gov.au/AUSSTATS/[email protected]/DetailsPage/7121.02012-2013?OpenDocument and http://www.abs.gov.au/AUSSTATS/[email protected]/mf/7503.0






http://www.abs.gov.au/AUSSTATS/[email protected]/DetailsPage/7121.02012-2013?OpenDocument






xvKnow more. Grow more.

December 2014



Figure 5:

Population BPopulation A

Goodstuff 421Goodstuff 386

A1 A2 B1 B2

A1A1 B1

B1B1 A1

A2A2 B1

B1B1 A2

A1A1 B2

B2B2 A1

A2A2 B2

B2B2 A2

‘Populations’ mayinclude inbredsfrom previous

breeding efforts.

Individual plants selected

(repeat several times)

Individualsself-pollinated

Some ‘early generation’crossing is done

to produce hybrids,and to choose better inbredsbased on hybrid performance.

Inbreds

Inbredscrossed

Hybrids resultfrom crosses

Hybrids advanced;seed produced

Hybrids tested;most discarded

Commercialnumber assigned;

seed sold to producers

Example of a breeding scheme for maize, showing how hybrids are produced. (Source: Hoeft et al. 2000) 11

Hybridsaresimilaringrowthanddevelopment,buttheyvarywidelyinagronomic

characteristicsandend-usequality.Whenselectingahybrid,itisimportanttoconsiderthe

potentialenduse,relativematurity,yieldpotentialanddiseaseresistance.

Theendusesofmaizegrainareprocessing(humanconsumptionorindustrialpurposes)

andstockfeed.Maizeisalsogrownforsilage.12

11 K.O’Keeffe(2009)Maizegrowthanddevelopment.PROCROPSeries,NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0007/516184/Procrop-maize-growth-and-development.pdf

12 DAFF(2012)MaizeproductioninQueensland.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize



http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0007/516184/Procrop-maize-growth-and-development.pdf


xviKnow more. Grow more.

December 2014



A.3.1 Maize for processing Maizegraintypesvaryfromverysoft,starchygrainwithlowtestweights,throughsemi-

dentandsemi-flint,toveryhardflintytypes(e.g.popcorn)withhightest-weights.The

harderflinttypescontainmoreproteinandlessstarchthanthesoft,starchytypes.

The‘grit’varieties,whichproducethehardsemi-flintkernels,areusedtomakebreakfast

cereals,confectioneryproductsorspecialtyproductssuchascornchips.

Grainsfromwaxy,highamyloseorwhitemaizehybridshavespecialstarchproperties

neededforotherareasofindustryandfoodprocessingsuchascornflour.

Ifthegrainistobeprocessed,thegrowermustselecthybridsthatarerecommendedby

theparticularmanufacturer,becausetheywillnotacceptotherhybrids.13

A.3.2 Maize for stockfeed Varietiesusedforstockfeedarechosenmainlyfortheiryieldpotentialratherthangrain

quality.Growerswillneedstoragefacilitiesifgrowingfeedmaize,tocaterforbuyers

demandingsupplythroughouttheyear.

A.4 Keywords

Maize,flint,dent,starch,production,yield,profitability

13 DAFF(2012)MaizeproductioninQueensland.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize

i More information

CJBirchet al.(2003)

Agronomy of maize

inAustralia:inreview

andprospect.In

5thAustralianMaize

Conference.




http://espace.library.uq.edu.au/eserv/UQ:9698/Agronomy_of_Maiz.pdf






Section 1 MAIZE - Planning/Paddock preparation

1Know more. Grow more.

December 2014



SECTION1

Planning/Paddock preparation

Maizeisasummer-growing,multipurposecerealcropthatneedswarm(butnothot)

daytimetemperatures,mildnightsandmoist,well-drainedsoiltomaximiseyield.The

growingseasonisusually120–150daysfromplantingtoharvest.

Maizeisgrownasbothadrylandandanirrigatedcrop.Ahigh-yieldingcropusesupto850

mmofwaterthroughevapotranspiration(ET)duringthegrowingseason.Alongthecoastal

beltandinthetablelands,cropscanusuallybegrownsuccessfullywithoutirrigation;

however,supplementaryirrigationwillimproveyields.

Maizecanbegrowntoproducegrainforarangeofhumanfoodandstockfeedmarkets,or

thewholeplantcanbeharvestedgreenforfodderorsilage.Yieldpotentialsaresimilarto

thoseofsorghum,butwithgreaterresponsetoirrigation.1

ThesuccessofmaizeasacropoptionthroughoutAustraliainrecentseasonshasmadeit

aviableoptionformanygrowersintothefuture.

Traditionally,maizehasbeenapopularoptiononlyincertaingeographicareas,butwith

advancesinhybridperformanceandagronomictechniques,thesuccessofthecropina

varietyofenvironmentshasincreased.Thesuccessofmaizeispartlyduetoitsversatility

withregardtoplantingtimeandthevariousend-useoptions.Grainfromvarioushybridsfills

bothfeedandspecialtyprocessingmarkets,andthecropiscommonlyusedtoproduce

bulktonnageofhigh-energysilage.

InareassuchasCentralQueensland,maizeisoftengrownunderdrylandconditions

inskip-rowformationssothattheplantscanmakethemostofavailablemoistureand

nutrientsandtheseasonalconditions.Maizehassomeadvantagesoversorghum,which

ismoretraditionallygrownintheregion;itsnaturalsenescencecharacteristicsmeanthat

itdiesdownattheendofitslifecycle,sodoesnotrequiresprayingoutwithaherbicideor

defoliantpriortoharvest.Itmaybesownearlierandlaterthantraditionalsorghumcrops,

whichaddsflexibilitytofarmingsystem.

Becauseofitsannuality,maizeoftenleavesresidualmoistureaftersenescence,allowinga

double-cropopportunityforwinterpulsecropsoraccumulatedmoistureforthefollowing

cropintherotation.

1 NMoore,LSerafin,LJenkins(2014)Summercropproductionguide2014.NSWDPIManagementGuide.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/agriculture/broadacre/guides/summer-crop-production-guide

i More information

TDixon(2013)Summer

grainspivotaltonorth’s

future. Ground Cover

Issue106.GRDC.




http://grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-106-Sept-Oct-2013/Summer-grains-pivotal-to-norths-future






December 2014



WiththewetconditionsthatcanbeafeatureoftheeasternstatesofAustralia,the

characteristicofsenescencehasallowedmaizetositthroughthedelugeand,inmany

cases,beharvestedwhenconditionsimprove.

Maizegenerallyhasadvantagesoverothercropsinitsabilitytoresistweatheringwhile

awaitingharvest,partlyduetohuskcoverparameters.Maizehybridsgenerallyhaveathick

huskcoveroverthecobtoprotectthegrainfromadverseweather.

InareassuchassouthernQueenslandandNewSouthWales(NSW),maizehasbecome

increasinglypopularasbothadrylandandanirrigationoption.Althoughcottonis

traditionallythemainirrigationcropinthoseregions,maizehasmadesignificantinroadsas

a crop rotation or planting partner option.

OntheupperLiverpoolPlains,maizestillprovideshealthygrossmarginscomparedwith

cottonbecauseofitsabilitytoestablishearlierintheseason,returnabetteryieldper

megalitreofirrigation,andsenesceandharvestwellbeforecottoncanbedefoliatedand

picked.

Thereisevidencethatcottoncropsthatfollowmaizecropshavemorevigourandhigher

yieldsthancotton-on-cottonrotationsinadjacentpaddocks.Maizeintheseareascanbe

plantedasearlyasAugustandSeptemberandaslateasJanuaryandevenFebruary.This

flexibilitymakesitaverygoodoptionunderirrigationconditionsbecauseitcanbeplanted

earlyandcanusemostofitswaterbeforethecottonplantutilisesitsmajorinputs.

Similarly,onalaterplant,themaizeisabletotakeadvantageofanyleftoverwater

allocationsandprovideaprofitableoption.

Inrecentseasons,maizehasbecomemorepopularforsilageinthetraditionaldairyregions

ofAustralia.Veryfewcropscanprovidethetonnesperhectareortonnespermegalitreof

maize.Thecropisaparticularlygoodfitinthedairysector,withthehigh-energy,low-

proteinmaizesilageaperfectcomplementtothehigh-proteinpastureandpasturesilage

producedonAustralianfarms.Maizeisoftenreferredtoasa‘recipecrop’anditwill

consistentlyproducehigh-qualityyieldsofsilageorgrainundergoodmanagement.2

1.1 Paddock selection

1.1.1 Soil typesMaizegrowswellonarangeofsoilsbutisbestondeep,well-drained,fertilesoilsthatare

slightlyacidtoneutral(pHCa5.5–7.0).3However,inmuchoftheinlandwherelargeareas

ofmaizearegrown,soilpHiscommonlyupto7.5oreven8.0.Inaddition,maizeismuch

moresusceptibletosalinesoilsthansorghum,wheatandbarley.4

2 TheCob,August2011.MaizeAssociationofAustralia,http://www.maizeaustralia.com.au/cob_files/autumncob2011.pdf



i More information

NRHulugalleetal.(2010)

Potential contribution

by corn and Bollgard

IIcottonrootstosoil

carbonstocks in a

furrow-irrigatedVertisol.

In19thWorldCongress

of Soil Science.

JHolden.Research

provesbenefitsofcornin

cotton rotation. DuPont

Pioneer.

PublicationsbyN

Hulugalle.Sydney

ResearchOnline.

UniversityofSydney.

i More information

TheCob,Autumn2011.

MaizeAssociationof

Australia.

FO’Gara(2007)Irrigated

maizeproductioninthe

top endoftheNorthern

Territory.Production

guidelinesandresearch

results.Technical Bulletin

No.326,Northern

TerritoryGovernment.


http://www.maizeaustralia.com.au/cob_files/autumncob2011.pdf






http://www.iuss.org/19th WCSS/Symposium/pdf/0160.pdf








http://www.pioneer.com/home/site/Australia/template.CONTENT/guid.DD42D44B-8DDE-B289-2EFA-9D7AD2940145/




https://sro.library.usyd.edu.au/browse?type=author&value=Hulugalle%2C+Nilantha&value_lang=en_US







http://www.nt.gov.au/d/Content/File/p/Tech_Bull/TB326.pdf










December 2014



Maizedoesnotgrowwellinsalinesoils.Yieldreductionsof10%to≥20%canbe

experiencedifsoilextractscontain2.0–4.0dS/m,respectively.Yielddeclineislikelyif

irrigationwaterhassalinityof>1.5dS/m.Seedlingandflowergrowthismostsensitiveto

salinity.5

Maize,likesorghum,isextremelysensitivetogerminatingandestablishinginsalinesoils,

buttoleranceimprovesdramaticallyinmaizeasitgrowsinbiomass.

Maizedoesnotgrowwellonpoorlydrainedsoils,somostirrigatedcropsaregrownina

minimumtillagesystemonpermanentraisedbeds.Farmersusingminimumtillagetogether

withpermanentbedsreportimprovementinsoilstructureaswellascostandtimesavings.6

Muchinlandmaizeinthenortherngrainsregionisgrownonclay-basedsoil,which,

generally,isgoodsoilwithhighwater-holdingcapacitybutmorepronetowaterloggingwith

eitherexcessivesummerstormsorover-irrigationearlyintheplantlife.Thissamesoiltype

isalsopronetocompactionbecauseofitsfineparticlesizeandclaycontent.

Maizecanhandleaverywiderangeofsoiltypesbothlighttexturedandheavyclays,

eventhoughclaysoilswithhighbulkdensitiescaninhibitrootdevelopmentandmoisture

extraction.Thisissimilarforothercropsbutbulkdensityvaluesof1.4andrisingwouldlimit

maizeyieldsunlessadequateirrigationwaterwasavailabletoalleviatethesoilconstraint.

Themaizeplantisvulnerabletosoilcompactionandthishasadetrimentaleffectonmaize

yieldinsomeirrigationsystems,particularlyiffarmersareforcedtoharvestunderwet

fieldconditionsorwherefieldpreparationoccursafterawetwinter.Inmanycases,the

compactionoccursinthebottomoftheactualfurrowfromlandpreparationthroughto

post-plantingoperations.

Soilcompactionhasmultipleeffectsontheplant:

• Itreduceswater-holdingcapacityandthereforeincreaseswaterlogging(causingan

anaerobicenvironment).

• Itreducestheplant’sabilitytodevelopanefficientrootsystemtoscavengemoisture

andnutrientsfromdepth.

• Waterschedulingwillbeshortenedbecauseoftheplantsinabilitytoscavengeatdepth

eventhoughtheprobemayindicateotherwise.

• Itmakestheplantmorepronetoroot,stalkandgraindiseasesbecauseofstress

throughinabilitytoscavenge.7Itcanalsocreateanunevencrop.

5 DAFF(2012)Varietiesandplantingofmaize.DepartmentofAgriculture,FisheriesandForestryQueensland,https://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/varieties-planting



i More information

PJElliotet al.(1992)

Managingsodicduplex

soilsfor furrow irrigation.

In6thAustralian

AgronomyConference.

NKMehrotraet al.(1986)

Soil–sodicity-induced

zincdeficiencyinmaize.

PlantandSoil92,63–71.

http://www.dpi.nsw.gov.

au/agriculture/resources/

soils/salinity/crops/

tolerance-irrigated

i More information

CJBirchet al.(2003)

Agronomy of maize


andprospect.In

5thAustralianMaize

Conference.

SClarry(2013)Different

pathstosuccessfor

Queenslandmaize

growers.GroundCover

Issue102.GRDC.

A Devereux et al.(2008)

Theeffectsofmaize

rotationonsoilquality

andnutrientavailabilityin

cottonbasedcropping.

In14thAustralian

AgronomyConference.






http://www.regional.org.au/au/asa/1992/concurrent/soil-stress/phtm.htm





http://link.springer.com/article/10.1007%2FBF02372267#page-1




http://www.dpi.nsw.gov.au/agriculture/resources/soils/salinity/crops/tolerance-irrigated










http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-102/Different-paths-to-success-for-Queensland-maize-growers





http://www.regional.org.au/au/asa/2008/concurrent/plant-nutrition/5815_devereuxaf.htm









December 2014



1.2 Paddock rotation and history

Legumerotationsandlongfallowsincreasetheavailabilityofsoilnitrogen(N;nitrate),

reducingtheNfertiliserrequirement.IndicativeNrequirementsformaizetargetyieldsare

showninTable1. 8

Table 1: Nitrogen rates (kg N/ha) for maize yield targets of 4–12 t/ha as influenced by crop rotation

DrylandmaizeNestimatesarebasedonLiverpoolPlainsclimateandsoilswithcultivationsolderthan25years

Previous crop to maize Yield target (t/ha)

Dryland Irrigated

4 6 8 10 12

Sorghum,cotton,sunflower,maize 100 150 200 250 300

Soybean – – 180 230 280

Cowpea, mungbean 70 120 – – –

Longfallowwheat 80 120 160 210 260

Long fallow faba bean 30 80 140 190 240

Longfallowchickpea 50 100 – – –

Lucerne 0 0 – – –

ManyoftheGroupBherbicideshaveplant-backperiodsof6–26monthsthatmustbe

observedbeforeplantingmaize.Plant-backrequirementsaresummarisedintheNSWDPI

Management Guide Weed control in summer crops. 9

1.3 Maize in crop rotations

Croprotationplaysanimportantroleinspreadingrisksassociatedwithseasonsand

markets.Asourknowledgeoftheagronomicvalueofrotationsincreases(reducing

diseaseseverity,loweringtherisksofherbicideresistance,controllinghard-to-killweeds,

maintainingarbuscularmycorrhizaelevels,legumesforanalternativesourceofN),fixed

croppingsystemsarebeingreplacedbyopportunity-basedsystemsthatincludeabroader

selectionofcrops.Assuch,summercroppingisplayinganincreasingroleintoday’s

farmingsystems.Themixofsummerandwintercroppingisrecognisedforimprovingcash

flowandreducingtheoverheadcostsforsmalltomid-sizeenterprises.Byspreadingthe

workloadthroughouttheyear,greaterproductivityisachievedfrommachineryandlabour

resources.

Excludingcottonandrice,sorghumaccountsfor64%ofthesummercropareasownin

NSW.However,sunflower,maize,mungbean,soybeanandsafflowercanaddflexibilityto

thesummercroppingprogram.Sunflowercanbesown4–6weeksearlierthansorghum.

Asspringrainfallcanbevariable,anearlysowingopportunitycouldmeanthedifference

betweensowingandnotsowingasummercrop.LegumesfixtheirownN,andmungbean

hasarelativelyshortcroppingperiod.Goodseasonscanbetakenadvantageofwhen

adouble-cropoptionsuchasmungbeancanbeincluded.Maizecanbegrownasan

excellentsourceofsilageaswellasforgrain,andtherearehybridswithadaptationto


9 JFleming,TMcNee,TCook,BManning(2012)Weedcontrolinsummercrops2012–13.NSWDPIManagementGuide.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/agriculture/pests-weeds/weeds/publications/summer

i More information

AustralianPesticides

andVeterinaryMedicines

Authoritywebsite.

JFleming et al.(2012)

Weedcontrolinsummer

crops2012–13. NSW

DPI Management Guide.


pathstosuccessfor

Queenslandmaize

growers.GroundCover

Issue102.GRDC.

D Rodriguez. Tactical

agronomyforsorghum

andmaize.Research

summary.Universityof

Queensland.


http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0008/248471/Weed-control-in-summer-crops-2012-13.pdf



http://www.dpi.nsw.gov.au/agriculture/pests-weeds/weeds/publications/summer


http://www.apvma.gov.au












http://www.qaafi.uq.edu.au/tactical-agronomy







December 2014



locationsacrossNSW.Maizeandsoybeanhavehumanconsumptionmarkets,providingan

opportunitytodiversifyfarmincome.10

1.3.2 In rotation with cottonRotationcropshavebeenutilisedbycottonproducersinAustraliasincetheearly1980s

forperceivedbenefitstosoilquality,cottonyieldandprofitability.Thebenefitsofwheatand

legumerotationsoncottoncropshavebeenwellestablished.However,maizerotationis

becomingmorepopularandithasgainedrecentinterestwithanecdotalfieldreportsof

increasesinthefollowingseason’scottonyieldsofupto25%.

Comparedwithcontinuouscottoncropping,amaizecropwithmoreshootandroot

biomassandashallowerrootsystemmayprovidemoreorganicmattertothesoiland

extractlesswaterandnutrientfromdeepersoils,whichwouldbenefitthesubsequent

cottoncrop.Inordertotesttheseideas,waterstresstrialswereestablishedintherainout

sheltersattheUniversityofQueenslandGattonCampus.

UniversityofQueenslandresearchersimposedwaterstresstreatmentsat38and71days

aftersowing.Soilmoisturecontentwasmonitoredusinganeutronmoisturemeterand

croprootgrowthwasinvestigatedwithsoilcorestakenconsistentlythroughoutthegrowing

seasonuntilcropmaturity.Theresultsoftheprolongedwaterstresstrialshowedthatmaize

hadhigherrootmassinuppersoillayers,butextractedlesswaterin30–70cmsoillayers.

Maizewithgreaterrootmassintheupperprofileresultedinincreasedmacroporesand

consequentlyincreasedinfiltration,whichmayleadtoincreasedwateravailabilitytothe

following cotton crop. 11

Benefitsandmanagementsuggestionsinclude:

• earlyplantingorlatedouble-cropplanting

• choiceofquicktomid-seasonhybridstosuityourschedule

• changingyoursummerherbicidepackagetocleanupdifficultweeds

• rotatingyourcottonpaddockswherediseaseisanissue

• harvestingearly(orlate)andgettingyourpaddockbackintoproductionforthenext

crop

• higheryieldingsubsequentcottoncrops12


11 ADevereux,SFukai,NRHulugalle(2008)Theeffectsofmaizerotationonsoilqualityandnutrientavailabilityincottonbasedcropping.In14thAustralianAgronomyConference,http://www.regional.org.au/au/asa/2008/concurrent/plant-nutrition/5815_devereuxaf.htm

12 Corn and cotton rotation. Du Pont Pioneer, http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Cotton_Corn_Rotation.pdf

Research trial results

1.3.1 In rotation with cottonRotationcropshavebeenutilisedbycottonproducersinAustraliasincetheearly1980s

forperceivedbenefitstosoilquality,cottonyieldandprofitability.Thebenefitsofwheatand

legumerotationsoncottoncropshavebeenwellestablished.However,maizerotationis

becomingmorepopularandithasgainedrecentinterestwithanecdotalfieldreportsof

increasesinthefollowingseason’scottonyieldsofupto25%.

Comparedwithcontinuouscottoncropping,amaizecropwithmoreshootandroot

biomassandashallowerrootsystemmayprovidemoreorganicmattertothesoiland

extractlesswaterandnutrientfromdeepersoils,whichwouldbenefitthesubsequent

cottoncrop.Inordertotesttheseideas,waterstresstrialswereestablishedintherainout

sheltersattheUniversityofQueenslandGattonCampus.

UniversityofQueenslandresearchersimposedwaterstresstreatmentsat38and71days

aftersowing.Soilmoisturecontentwasmonitoredusinganeutronmoisturemeterand

croprootgrowthwasinvestigatedwithsoilcorestakenconsistentlythroughoutthegrowing

seasonuntilcropmaturity.Theresultsoftheprolongedwaterstresstrialshowedthatmaize

hadhigherrootmassinuppersoillayers,butextractedlesswaterin30–70cmsoillayers.

Maizewithgreaterrootmassintheupperprofileresultedinincreasedmacroporesand

consequentlyincreasedinfiltration,whichmayleadtoincreasedwateravailabilitytothe

following cotton crop. 11

i More information

A Devereux et al.(2008)

Theeffectsofmaize

rotationonsoilquality

andnutrientavailabilityin

cottonbasedcropping.

In14thAustralian

AgronomyConference.

Corn and cotton rotation.

Du Pont Pioneer.

i More information

Maize–groundnut

rotation.Maize–legume

cropsimulations.APSIM.

Growingsoybean

and maize in rotation.

InternationalInstituteof

Tropical Agriculture.

ZBerzsenyi et al.(2000)

Effectofcroprotation

andfertilisationon

maizeandwheatyields

andyieldstabilityina

long-term experiment.

EuropeanJournalof

AgronomyVol.13.






http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Cotton_Corn_Rotation.pdf











http://www.apsim.info/Documentation/TrainingManualsandResources/APSIMTraining%28SIMLESA%29/MaizeLegumecropsimulations.aspx



http://www.iita.org/c/document_library/get_file?uuid=bf99e065-3324-4b4f-8f96-cfdb44af5a9c&groupId=25357




http://www.sciencedirect.com/science/article/pii/S1161030100000769










December 2014



1.3.3 Pest and disease impactsManagementofdiseasesinmaizemustaimtoreduceboththeopportunityfordisease

infectionsandthelikelihoodthatmycotoxinswill beproducedwheninfectionsoccur.Strategiesincludingcroprotationcanbeeffectiveforpreventativemanagementofdiseases

suchasrust.

Inoculumofdiseasesincludingturcicumleafblightornorthernleafblight(Exserohilum

turcicum)overwintersonstubbleandmaizevolunteersanditshouldbeaccountedforin

rotationplans.Inoculumisdispersedbywindandrainsplash.

CroprotationisalsoakeystrategyinmanagingpestssuchasAfricanblackbeetle

(Heteronychus arator) inmaize,includingavoidingfollowingrecentlycultivatedpasture.In

claysoils,samplingtheseedbedpriortoplantingisdifficult,butwarrantediftheriskishigh.

Toestimatethesoilpopulation,digandsievesoilfrom10randomlylocatedquadrats(20

cm,30cmindepth).Theonlyinsecticidetreatmentavailableisanin-furrowapplicationof

chlorpyrifosduringplanting.However,thistreatmentisnoteffectivewhenbeetlenumbers

arehigh(≥10individuals/m)orwhenswarmsofbeetlesflyintothecropafterplanting.

Becausewireworms,includingtruewireworm(Agrypnus variabilis)andfalsewireworms

(Pterohelaeus darlingensis, P. alternatus, Gonocephalum macleayi),haveawidehostrange,

theycanbepresentirrespectiveofcroprotationorweedcontrol.13

1.4 Fallow weed control

Timelycultivationisavaluablemethodofkillingweedsandpreparingseedbeds.Most

growersusecombinationsofmechanicalandchemicalweedcontroltomanagetheir

fallowsorstubbles.

Thebasisofasuccessfuldrylandsummercropisaweed-freefallow.No-tillandminimum-

tillfallowshavebecomethenorm;no-tillhasenabledcropstobesownattheoptimum

timeandtobesownwhenitistoodrytosowintoacultivatedfallow.Inaddition,no-till

oftenreducesoperatingcoststolessthanthoseforcultivatedfallows,withsignificant

machineryandtractor-timesavings.

Opportunitydouble-croppingfollowingwintercerealshassucceededwherethereis

sufficientsoilmoisture.Inno-tillagesystems,stubbleretentionisvitalforimprovingsoil

structure,reducingsoilerosionanddegradation,storingsoilmoistureandprovidinga

wetterseedbed.Farmershavemovedawayfromcultivatingfallowstominimum-andno-

tillagebysubstitutingknockdownandresidualherbicides.14

Paddocksgenerallyhavemultipleweedspeciespresentatthesametime,makingweed-

controldecisionsmoredifficultandofteninvolvingacompromiseafterassessmentof

theprevalenceofkeyweedspecies.Knowledgeofyourpaddockandearlycontrolof


14 JFleming,TMcNee,TCook,BManning(2012)Weedcontrolinsummercrops2012–13.NSWDPIManagementGuide.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/agriculture/pests-weeds/weeds/publications/summer

i More information

POseiBonsu,JYAsibuo

(2013)Rotationaleffects

oflegumeson maize

yield.InternationalJournal

ofScientific&Technology

ResearchVol.2.

BL Ma et al.(2003)

Croprotationandsoil

Namendmenteffects

on maize production

ineasternCanada.

CanadianJournalofSoil

ScienceVol.83.

JLaueret al.(1997)The

cornandsoybeanrotation

effect.AgronomyAdvice.

UniversityofWisconsin.

CNkwiine(1991)Effectof

soybean–maize cropping

rotationonsoybean

rhizobialpopulationand

soybeannodulation.

MakerereUniversity,

Uganda.

i More information

MCongreve(2014)

Managingherbicide

resistantweedsinthe

summerfallow.GRDC

UpdatePapers.


Weedcontrolinsummer

crops2012–13. NSW

DPI Management Guide.

FYeganehpooret

al.(2014)Effects

ofcovercropsand

weekmanagementon

cornyield.Journalof

theSaudiSocietyof

AgriculturalSciences.






http://www.ijstr.org/final-print/apr2013/Rotational-Effects-Of-Legumes-On-Maize-Yield.pdf






http://pubs.aic.ca/doi/abs/10.4141/S02-071







http://corn.agronomy.wisc.edu/AA/A014.aspx




http://www.ctahr.hawaii.edu/bnf/Downloads/Dissertations/Nkwinne Thesis.htm







http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2014/07/Managing-herbicide-resistant-weeds-in-the-summer-fallow









http://www.sciencedirect.com/science/article/pii/S1658077X1400023X









December 2014



weedsareimportantforgoodcontroloffallowweeds.Informationisavailableforthemost

commonproblemweeds;however,foradviceonindividualpaddocksyoushouldcontact

youragronomist.

Benefitsoffallowweedcontrolaresignificant:

• Conservationofsummerrainandfallowmoisture(thiscanincludemoisturestored

fromlastwinterorthesummerbeforeinalongfallow)isintegraltowintercroppingin

thenorthernregion,particularlysoastheclimatemovestowardssummer-dominant

rainfall.

• Modellingstudiesshowthatthehighestreturnoninvestmentinsummerweedcontrol

isforlightersoilsorinsituationswheresoilwaterispresentthatwouldsupport

continuedweedgrowth.15

TheNorthernGrowerAlliance(NGA)istrialingmethodstocontrolsummergrasses.Key

findingsinclude:

1. Glyphosate-resistantand-tolerantweedsareamajorthreattoourreducedtillage

croppingsystems.

2. Althoughresidualherbicideswilllimitrecroppingoptionsandwillnotprovide

completecontrol,theyareakeypartofsuccessfulfallowmanagement.

3. Double-knockherbicidestrategies(sequentialapplicationoftwodifferentweed-

controltactics)areusefultoolsbuttheherbicidechoicesandoptimaltimingswill

varywithweedspecies.

4. Otherweedmanagementtacticscanbeincorporated,suchascropcompetition,to

assistherbicidecontrol.

5. Cultivationmayneedtobeconsideredasasalvageoptiontoavoidseedbank

salvage.

1.5 Seedbed requirements

Beinglarge-seeded,maizedoesnotneedaveryfineseedbed,althoughthisisdesirable,

becauselargeclodswillreducetheeffectivenessofpre-emergentresidualherbicides.In

coastalwettropics,maizecanbeno-tilledintocanetrash,avoidingcultivationpriortothe

wetseason.

Rowspacingneedstomatchtheharvesterfront,anditmaybenecessarytoremove

compactionwitharipperwhereamaizerowcoincideswithanoldsugarcaneinter-row.16

Theuptakeofno-tillage,tramliningandpermanentbeds(orbedrenovation)hasseen

areductionintheeffectofcompaction,particularlyunderdrylandfarmingoperations.If

compactionisaknownproblem,deeprippingorsubsoilingisrecommended.Rippingthe

furrowswillalsoenhancewaterinfiltrationwithbedorfurrowirrigation.

15 GRDC(2012)Makesummerweedcontrolapriority.Summerfallowmanagement.Southernregion.GRDCFactSheetJanuary2012,http://www.grdc.com.au/Resources/Factsheets/2012/01/Summer-Fallow-Management-Southern-Region-Fact-Sheet

16 DAFF(2010)GrowingmaizeinthecoastalWetTropics.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/varieties-planting/growing-maize-in-the-coastal-wet-tropics#Paddock_selection

i More information

http://grdc.com.

au/Resources/

Factsheets/2014/08/

Summer-fallow-spraying


http://www.grdc.com.au/Resources/Factsheets/2012/01/Summer-Fallow-Management-Southern-Region-Fact-Sheet


http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/varieties-planting/growing-maize-in-the-coastal-wet-tropics#Paddock_selection


http://grdc.com.au/Resources/Factsheets/2014/08/Summer-fallow-spraying






December 2014



Improvedsoilstructureandmoistureconservationhavealsoimprovedusingminimum/no-

tillagetechniques.

Maizeispronetowaterlogging;therefore,irrigationfieldsthathavenotbeenproperly

levelledwillsufferunevennessacrossthefieldandareductioninyield(Figure1).

Whenplantingdryandwateringup,thereisnoneedtoplantdeeperthan2–4cm.The

largeseedofmaizeallowsgrowerstheflexibilitytoplantalittledeeperifchasingmoisture,

aslongasgroundtemperaturesareadequate.17

Figure 1: Maize is prone to waterlogging so performs best on levelled fields. (Photo: Pacific Seeds)

1.6 Soil moisture

1.6.1 Water requirementsMaizeproducesalargeamountofdrymatterandgrain,butitsyieldislinearlyrelatedto

ETandthusthemoisturesupplied.Maizerequires500–800mmastheoptimalrangefor

yield,dependingonclimaticconditions18.Waterloggingcanbeasdetrimentaltomaize

yieldasinsufficientmoisture.Althoughmaizehasahighwaterrequirement,itcangrow

andyieldwithaslittleas300mmrainfall(40–60%yielddeclinecomparedwithoptimal

conditions)dependingonsoiltypeandstoredsoilmoisture.Cropfailurewouldbeexpected


18 BRaymond,GHarris.Irrigatedcorn—bestpracticeguide.InIrrigatedmanagementofgraincrops.WATERpak—aguideforirrigationmanagementincottonandgrainfarmingsystems,http://www.moreprofitperdrop.com.au/wp-content/uploads/2013/10/WATERpak-4_3-Irrigated-Corn-best-practice.pdf




http://www.moreprofitperdrop.com.au/wp-content/uploads/2013/10/WATERpak-4_3-Irrigated-Corn-best-practice.pdf




December 2014



if <300 mm of rain or irrigation were received in-crop. 19However,cropsuccessdepends

onsoiltypeandstartingsoilmoisture.SomeofthebestVertosolscanhold250–300mmof

plant-availablewaterforsummercrops,soonthesesoils,200mmin-croprainfallcanstill

produceaviableyield.

1.6.2 Crop water useMaizeoriginatedinMexico,anditismainlygrowninthewarmertemperateregionsand

humidsubtropics.ItisaC4plant,whichmeansthatithaspotentiallymoreefficientuseof

CO2,solarradiation,waterandNinphotosynthesisthanC3crops.Water-useefficiency

(WUE)ofmaizeisapproximatelydoublethatofC3cropsgrownatthesamesites.Its

transpirationratio(moleculesofwaterlostpermoleculeofCO2fixed)is388,corresponding

to0.0026inWUE(Jensen1973),whereasthatofwheatis613andsoybean704.

Althoughmaizemakesefficientuseofwater,itisconsideredmoresusceptibletowater

stressthanothercropsbecauseofitsunusual(monoecious)floralstructurewithseparate

maleandfemalefloralorgansandthenear-synchronousdevelopmentoffloretsona

(usually)singleearborneoneachstem.

Maizehasdifferentresponsestowaterdeficitaccordingtodevelopmentstage(Cakir2004).

Droughtstressisparticularlydamagingtograinyieldifitoccursearlyinthegrowingseason

(whenplantstandsareestablishing),atflowering,orduringmid–lategrainfilling(Heiseyand

Edmeades1999).Attheseedlingstage,waterstressislikelytodamagesecondaryroot

development.Duringstemelongation(afterfloralinitiation),leavesandstemsgrowrapidly,

requiringadequatesuppliesofwatertosustainrapidorgandevelopment;water-stressed

plantsareshorterandwithreducedindividualandcumulativeleafarea(Muchow1989).

Themostcriticalperiodforwaterstressinmaizeis10–14daysbeforeandafterflowering,

withgrainyieldreduced2–3timesmorewhenwaterdeficitcoincideswithfloweringthan

withothergrowingstages(Grantet al.1989).Duringthisperiod,eargrowthissusceptible

tocompetitionfromotherorgansthatarestillgrowing,asitsgrowthissourcelimited,often

leadingtolowgrainnumberperearand,occasionally,barrenears.Grainyieldofmaize

sufferingwaterstressatfloweringandduringgrainfillishighlycorrelatedwithkernelnumber

perplant(BolanosandEdmeades1996),indicatingtheimportanceofadequatewater

suppliesduringflowering.

TheWUEofmaizeisafunctionofmultiplefactors,includingphysiologicalcharacteristics

ofmaize,genotype,soilcharacteristicssuchassoilwater-holdingcapacity,meteorological

conditionsandagronomicpractices.ToimproveWUE,integrativemeasuresshouldaimto

optimisecultivarselectionandagronomicpractices.

19 SBelfield,CBrown(2008)Fieldcropmanual:maize.AguidetouplandproductioninCambodia.CambodianAgriculturalResearchandDevelopmentInstituteandNSWDepartmentofPrimaryIndustries,http://aciar.gov.au/files/node/8919/maize%20manual%2072dpi.pdf

i More information

CJBirchet al.(2003)

Agronomyofmaize


andprospect.In

5thAustralianMaize

Conference. cusin


http://aciar.gov.au/files/node/8919/maize manual 72dpi.pdf


http://espace.library.uq.edu.au/view/UQ:9698/Agronomy_of_Maiz.pdf








December 2014



1.6.3 Modification of agronomy to improve WUEDroughtresistanceofacropcanbeaffectedbymanyagronomicmeasures.Some

measuresarecriticalforimprovingWUEandcanbeachievedwithrelativelysimplechanges

toproductionpractices.

Planting date

Shortcropdurationcontributesanimportantattributeofdroughtescape(Debaeke

2004);earliermaturinggenotypesarebetteradaptedtoenvironmentswheretheperiodof

favourablewatersupplyisshortandtheriskofwaterstressisrelativelyhigh.Plantingdate

coupledwithselectionofappropriategenotypesfacilitatesdroughtescapebymatching

thecropgrowthcycletorainfallandtemperaturepatternstominimisethechanceof

exposuretowaterdeficitatdrought-susceptiblestages.Ofcourse,selectionofplanting

dateandcultivarmustbedonetoensurethatthethermalenvironmentisfavourabletocrop

establishmentandcompletionofthelifecycle.Wherethelengthofthegrowingseasonis

limitedbythedurationoftherainyseason,theearliestpossibleplantingofsuitablecultivars

reducestheprobabilityofdroughtduringthelategrain-fillingstage(HeiseyandEdmeades

1999).Amodelingapproachtoselectionofplantingdate–cultivarcombinationsisincluded

inBirchet al.(2006).

Planting geometry

PlantinggeometriesorplantingpatternscaninfluenceWUE,andtherearemanyplanting

patternsformaizeaccordingtotheenvironmentandculturalconditions.Themostcommon

isanequal-row-spacingpatternofabout75–100cmrowspacing,withanddifferentintra-

rowplantspacingproducingdifferentplantpopulationdensities.(Typicallythisis25,000–

33,000plants/hafordrylandplantingdependingoncultivarandregion,and65,000–80,000

plants/haunderirrigationdependingoncultivar,soiltypeandregion.)

Intercroppingmaybeusedwithmaize;ithasthebenefitofusingwaterfromdifferentsoil

layersbythecompanioncropsandenhancesoverallWUEwherewatersupplyisadequate

(Adikuet al.1998).Skip-rowsowing(with1rownotplantedbetweenevery2or3rows

ofsowing)hasbeenproposedasameansofimprovingcropreliabilitybyrestrictingwater

useearlyintheseasonandmaintainingareserveofwaterinthesoilinthewiderowspace

producedbytheomittedrow.ResearchhasidentifiedlimitedresponseinyieldorWUEby

usingsingle-skipinmaize,ashasbeenconfirmedinsorghum.Theremaybecircumstances

wherewiderowsarebeneficial,butAustralianresearchtodateisunsupportiveofthe

practice.

Tillage

Basedonthelevelororganicresiduesonthesoilsurface,twobroadclassifications

oftillageareused:conventionaltillageandconservationtillage.Resultsofvarious

investigationsfromalmostallworldclimaticzonessuggestthatploughingcauses

commonsoil-relatedproblemsofcompaction,soilerosion,reducedwaterpercolation

andthusincreasedrunoffandhighenergyandtimerequirements(Titi2003).Bycontrast,

conservationtillage,includingno-tillage,ridgetillage,mulchtillage,andanysystemswith

atleast30%residuecoverremainingafterplanting(Derpsch2001),isgenerallydesigned

toreducesoilerosion(Reinbottet al.2004);italsoimproveswaterinfiltration(Guzha2004)

andwaterstorageandthusyieldpotentialandWUE(Hartkampet al.2004).




December 2014



Residue retention and plastic mulch

Insemi-aridareas,asmuchas50%oftotalETfromacropcanbelostthroughevaporation

fromthesoilsurface(UngerandStewart1983).Mulchingwithcropresiduesisanobvious

waytoreduceevaporation,anditmayhaveotherdesirableeffectssuchasreducingrunoff,

increasinginfiltration,anddecreasingsurfacetemperature,contributingtheimproveWUE

(Hartkampet al.2004).

Usually,surfacemulchingreducesevaporationbyprotectingthemoistlayerofaircloseto

thesurfacefromwind,andmoderatessoiltemperature.Maximumsoiltemperatureisoften

reducedbecausemulchingmaterialsgenerallyreflectmoresolarradiationandhavelower

thermalconductivitythansoil(JalotaandPrihar1998).Retentionofcropresiduecoupled

withminimumtillageimprovesseveralmeasuresofsoilquality,sustainsorimprovescrop

production,andincreasesWUEofmaizeinsemi-aridsubtropical(Gicheruet al.2004;

Rahmanetal.2005)andhumidtropical(Pramanik1999)areas.

Plasticmulchingisawell-establishedtechniqueforincreasingtheprofitabilityofmany

horticulturalcrops,andisbeingconsideredmorewidelyforfieldcrops.Largeincreasesin

yieldhavebeenachievedbyusingplasticmulchingonrainfedmaize,morethandoubling

yields(Fisher1995).Incoolclimatesthataremarginalforcropestablishment,plasticmulch

mayincreasetemperaturewhileprotectingwaterfromevaporation.Forcotton,useof

integratedmicro-topographyandplasticmulchhasincreasedWUEfrom0.49to0.76–0.86

kg/m3(Jinet al.1999),butadoptionofthistechnologydependsoncost-effectivenessand

overcomingconcernsaboutin-fielddegradationorremovalanddisposalofusedplastic

film.

Weed control and fertiliser use

Weedscompetewithagriculturalcropsforlight,nutrientsandwater(Norsworthyand

Frederick2005).Theimpactofweedsdependsonthetypeandintensityofinterference

withcropplants,andinmaize,likeothercrops,effectivecontrolofweedsleadstomore

efficientuseofwater(PetersonandWestfall2004).

Themostimportantmanagementinteractioninmanydrought-stressedmaizeenvironments

isbetweensoilfertilitymanagementandwatersupply.Inareassubjecttodroughtstress,

manyfarmersarereluctanttoriskeconomiclossbyapplyingfertiliser,strengtheningthe

linkbetweendroughtandlowsoilfertility.Manyreviewpapersdealwiththeunderlying

physiologyandindividualnutrienteffectsoncropyieldandthusWUE;reducedplantgrowth

rateinnutrient-deficientplantsisgenerallyassociatedwithreducedWUE(Bacon2004).

Therefore,managementofnutrientsupplyisastrategytoimproveWUE.Forexample,

Ogola et al.(2002)reportedthattheWUEofmaizewasincreasedbyapplicationofN,

and Gao et al.(2004)foundthatsilicon,althoughnotwidelyconsideredaplantnutrient,

improvesWUEinmaizeplantsunderwaterstressbyreducingleaftranspirationandwater

flowrateinxylemvessels.

Irrigation management

Althoughonlyabout18%ofcroplandisirrigated,itaccountsforabout40%ofworldcrop

production(Gleick2000)andtwo-thirdsoftotalriceandwheatproduction(Rosengrant

2000).




December 2014



TheWUEcanbeimprovedwithbettersystemsforwaterconveyance,allocationand

distribution(Hamdyet al.2003),andwaterlossescanbegreatlyreducedbyusing

advancedirrigationmethods,includingdripirrigationsystemsthatallowwatertobe

deliveredpreciselywhenandwhereitisneeded.Averageapplicationefficienciesofdifferent

systemsare:surface(flood)irrigation60–90%,sprinklerirrigation65–90%,dripirrigation

75–90%(Fairweatheret al.2003).Distributionuniformityinthefieldisalsoimportantfor

enhancingWUEandisfavouredbyprecisedeliverysystems.

Managementofmaizeirrigationatthefieldscalecanbeimprovedbyquantifyingthewater

balanceandusingadvancedtechniquesforirrigationschedulingformoreeffectiveand

economicuseoflimitedwatersupplies.Irrigationschedulingisnotnecessarilybasedonfull

cropwaterrequirement,butrather,designedtoensuretheoptimaluseofallocatedwater.

Deficit(orregulateddeficit)irrigationisonestrategyformaximizingWUEforhigheryields

perunitofirrigationwaterapplied.Thecrop(e.g.maizecrop)isexposedtoacertainlevel

ofwaterstresseitherduringaparticularperiodorthroughoutthegrowingseason,without

significantreductioninyields(SepaskhahandGhahraman2004).Successwithdeficit

irrigationismoreprobableinfinelytexturedsoilssuchasVertosolsofthenortherngrain

beltofAustralia,bymakingwateravailableatcriticalstagesofmaizedevelopment.Kanget

al.(2000a)reportedthatsoildryingattheseedlingstageplusfurthermildsoildryingatthe

stem-elongationstageisanoptimumirrigationmethodformaizeproductioninasemi-arid

area.Alternatefurrowirrigation(oneofthetwoneighboringfurrowsisalternatelyirrigated

duringconsecutivewatering)andcontrolledalternatepartialroot-zoneirrigation(partofthe

rootsystemisexposedtodryingsoilwhiletheremainingpartisirrigatednormally)arealso

waystoincreaseWUEofmaize(Kanget al. 2000b;KangandZhang2004).

NumerousstrategiesareavailableforimprovementofWUEinmaize.Theseincludeplant

improvementstrategiesusingconventionalmethodologiesandbiotechnology,anda

rangeofagronomicpractices.Acombinationofbothwillbeneededtooptimisemaize

productionaswatersuppliesbecomemorelimiting,withcarefulattentionbeinggiventothe

combinationofpracticesthatoptimiseWUEandcropreliability.20

1.6.4 IrrigationWell-irrigatedmaizecropsusewaterveryefficiently,commonlyyielding16–18kggrain/

ha.mmwater.Trialworkhasrecordedefficienciesinexcessof20kggrain/ha.mmwater.

IrrigationWUEisaffectedbycropagronomy,irrigationsystemefficiencyandseasonal

conditions—primarilyevaporationandin-croprainfall.Ingeneratingyieldresponseto

appliedwater,itisasimportanttoavoidwaterloggingstressasitistoavoidstress

frommoisturedeficits.YieldsachievedinirrigatedmaizetrialsconductedbytheNSW

DepartmentofPrimaryIndustriesareshowninTable2. 21

20 R Huang et al.(2006)Wateruseefficiencyinmaizeproduction—thechallengeandimprovementstrategies.In6thTriennialConference,MaizeAssociationofAustralia,http://www.maizeaustralia.com.au/events_files/Water%20use%20efficiency%20in%20maize%20-%20CJ%20Birch.pdf


i More information

R Huang et al.(2006)

Wateruseefficiency

inmaizeproduction—

thechallengeand

improvementstrategies.

In 6thTriennial

Conference, Maize

AssociationofAustralia.

CBirchet al.(2008)

Usingmodellingand

agronomytoimprove

reliabilityofmaizeasa

rainfedcropinnorthern

NewSouthWales

andsouthwestern

Queensland.In14th

AustralianAgronomy

Conference.

R Huang et al.(2006)The

agriculturalwatersupply

challenge—theneed

forimprovedwateruse

efficiency.In6thTriennial

Conference, Maize



http://www.maizeaustralia.com.au/events_files/Water use efficiency in maize - CJ Birch.pdf












http://www.regional.org.au/au/asa/2008/poster/farming-uncertain-climate/5666_stephenk.htm










http://www.maizeaustralia.com.au/events_files/Agricultural water supply challenge - CJ Birch.pdf









December 2014



Table 2: DPI irrigated maize hybrid evaluation trials

SitesatLiverpoolPlains2002-2008

Hybrid Seed brand No. of trials Mean yield (t/ha)32P55 Pioneer 1 10.61

Colossus HSRSeeds 3 10.50

PAC 675 PacificSeeds 3 10.49

31G66 Pioneer 2 10.45

3153 Pioneer 5 10.35

34N43 Pioneer 1 10.32

33V15 Pioneer 1 10.31


Olympiad HSRSeeds 3 10.30


Hycorn675IT PacificSeeds 3 10.23

33T39 Pioneer 1 10.17

Hannibal HSRSeeds 4 10.16

31H50 Pioneer 4 9.94

XL80 PacificSeeds 1 9.74

34B28IT Pioneer 1 9.72

Victory Nuseed 2 9.38


Maximus HSRSeeds 2 8.85

l.s.d.(P=0.05) 1.12t/ha

Water budgeting

Theamountofwaterrequiredtoproducehigh-yieldingmaizedependstemperatureand

relativehumidityduringthegrowingseasonaswellasotherclimaticfactorsaffectingthe

rateofevaporationfromthesoilandtranspirationfromtheplant.AtGunnedah,budgeting

3–6MLofirrigationwaterappliedtothefieldperhawillsatisfycropwaterrequirementsin4

of5years.IntheMurrumbidgeevalley,irrigationwateruserangesfrom6to10MLapplied

tothefield.Theaveragebudgetis8–9ML/ha.

Afree-to-useonlinetoolCropWaterUsecanbeusedtomodelthecropwaterrequirement

forirrigatedmaizeforlocationsinnorthernNSWandQueensland22.

Waterbudgetingisparticularlyimportantintheplanningstagesofmaizeproduction

becausemaizeislesstolerantofmoisturestressthanothersummercrops.Irrigation

strategiescanbebasedonfullorlimitedirrigation;however,ETisusuallylinearlyrelatedto

theyieldofthecrop,andmoisturestressatanystageofthecropdevelopmentwillreduce

yieldwithouttheabilitytocompensatelater.

Types of irrigation

Maizeistypicallyirrigatedusingfurroworfloodirrigation.Sprinkler(lateralmoveandcentre

pivot)anddripirrigationmethodsarewellsuitedtohigh-yieldingmaizeproduction,partly

becauseofthelowerpotentialforwaterloggingwhenusingthesemethods.Thehigher

22 CropWaterUse.MoreProfitperDropIrrigatedFarmingSystems,http://www.moreprofitperdrop.com.au/irrigation-management/have-you-ever-wondered-how-much-water-a-crop-really-needs/


http://www.moreprofitperdrop.com.au/irrigation-management/have-you-ever-wondered-how-much-water-a-crop-really-needs/





December 2014



systemefficienciesofthesemethods,asshowninTable3below,areanothersignificant

advantage in maize production. 23

Table 3: Indicative efficiency of irrigation methods

Irrigation method Indicative system efficiency Flood or furrow 60–70%

Sprinkler—centrepivot,lateralmove 85–90%

Drip 90–95%

Peak water use

Dailywateruseformaizewillvarythroughtheseasondependingontheweatherconditions

andstageofgrowth.Thecropsabilitytotakeupwaterincreaseswiththedevelopment

ofthecanopy.Highwateruseoccursfromtasselappearancethroughtoearlydentgrain

maturity.Approximately70%ofthecrop’stotalwaterusewilloccurinthiswindow5–12

weeksafterplanting.Duringthistime,cobinitiation,flowering,pollinationandkernelset

occur.

Peakwateruseoccursduringthe3weeksfollowingsilking(weeks10–12).Thelargerthe

canopy,thegreaterthewateruseduringthisperiod.Taller,densercropswillusemore

waterbecausetheyinterceptmorelightandtheyareexposedtomorewind. 24

Scheduling irrigations

Irrigationfrequencydependsontheinteractionbetweencropgrowth,storedsoilmoisture

andclimaticconditions—temperature,rainfall,windandhumidity.Moisturestresswill

occurbeforethecrophasextractedalloftheplantavailablewaterinthesoilprofile.Early

intheseason,whentherootsystemisdeveloping,itisrecommendedthatirrigationsare

scheduledtooccurwhen40%oftheavailablewaterisdepleted.

Beyondtassellingthedeficitcanincreaseto50%,exceptwhenconditionsofextreme

evaporativedemandprevail.Thedeficitcanincreaseto75%whengrainhasreachedearly

dent.

Usingtherecommendeddeficits,inthenortherninlandregionofNSWtheirrigation

requirementformaizeissimilartocotton,with6–8irrigationsusuallyrequired.Cropsin

thesouthernNSWinlandregionarelikelytorequire10–12irrigationsthroughtheseason.

Duringpeakwateruse,thedeficitwillbereachedevery7–10days,dependingonclimate.

Dailywater-usedemandscanbeestimatedwheredailyevaporationinformationisavailable.

Thedailywateruseofmaizeatkeystagesofgrowth,relativetobothpanevaporationand

theETofa‘standard’,croparepresentedinTable4.Alargeproportionofthesoilwater










December 2014



istakenupbytherootsfromwithinthetop30cmoftheprofile.Monitoringsoilmoisture

conditionsat25cmisalsoausefulguidetomoistureavailability. 25

Table 4: Daily water use of maize at key growth stages

Maize growth stage Daily crop water use relative to:

Pan evaporation Evapotranspiration of a standard crop

5-leaf 25% 30%

Silking 95% 120%

Lategrainfill 50% 60%

Maizeexpressestheeffectsofmoisturestressthroughanupwardcurlingoftheleaf

margins.However,thisisnotausefulvisualcueforschedulingirrigations.Onhotsummer

days,theevaporativedemandcanbegreaterthanmaize’scapacitytotakeinwater.This

leadstostresssymptomsevenwhenthereisamplesoilmoisture. 26

Timing the first irrigation

Plantingthecropintoafullprofileofsoilmoistureencouragesrapidrootgrowthandavoids

waterlogging.Thismayrequireapre-sowingirrigation.Whenstartingwithafullprofileof

moisture,maizeshouldnotrequireanirrigationbeforetheV4stage;however,thefirst

in-cropirrigationshouldoccurbeforeanyvisiblesignsofmoisturestress.Thereisarapid

increaseindemandfornutrientsduringtheperiod5–8weeksafteremergence.Thefirst

irrigationshouldbetimedtoensurethataccesstonutrientsisnotlimitedbywateratthis

time,anditiscriticalthatnutrientuptakenotbeinterruptedbywaterlogging. 27

Irrigation scheduling

Astemperaturesincreaseandthecropmovesintorapidvegetativegrowth,theplant-

availablewatercapacityshouldbemaintainedbetweentherefillpoint(50%)andfull(100%).

Priortotassellingthroughtomilkstage,thecropwillrequiremorefrequentirrigationsto

maintainpeakyield,particularlyinhot,drierconditionsandwhenthecropsaretallerwith

thickercanopiesduetohybridchoiceoragronomicmanagement.

Irrigationsshouldbescheduledbasedontheuseofcommercialin-cropmonitors.

Loggersthatcontinuouslymonitormoistureatdifferentdepthsthroughouttheprofile(e.g.

EnviroSCAN® and C-Probe®)allowaccurateandcontinuoussoil-moisturemonitoring.This

technologyalsoallowsuserstoaccesstheinformationthroughwirelesscommunication,so

soilprofilescanbemeasuredfromcomputerssomedistanceaway.Neutronprobesalso

measureavailablesoilwater;however,loggingisnotcontinuousandonlyoccursasoften

asmanuallypossible.













December 2014



OtherschedulingsystemsbasedonweatherdatasuchasWaterSched2,developedby

DepartmentofAgriculture,FisheriesandForestryQueensland(DAFF),arealsoavailable.

ThesetoolsutilisedailyandseasonalweathertocreateandestimatecropETsothat,

combinedwithon-farmdatasuchassoiltypeandcropstage,irrigationrequirementscan

beestimated.

Impacts of stress

Moisturestressinthefirst4weeksofgrowthcanreduceleafexpansionandcropheight

butislessdetrimentaltoyieldthanlaterstresses.Stressattasselinitiationresultsinsmaller

cobs,andstressattasselling(flowering)andsilking(pollination)canresultinunsetkernels.

Moisturestressfollowingsilkingleadstoreducedkernelsizeandincreasestheriskof

mycotoxincontaminationinthegrainsample.Fourconsecutivedaysofmoisturestress

betweentassellingandsilkingcanreduceyieldby30%.Grainyielddeclinesby6–8%

perdayofmoisturestressduringthepeakwater-useperiod.Afteraperiodofmoisture

stress,thecropmaytakeseveraldaystorecoverregardlessofsoilmoisture.Ifirrigationis

appliedafteraperiodofstress,increasetheflowratetominimisetheperiodofinundation.

Prolongedsaturationincreasestheriskoflodgingifconditionsbecomewindy.Ideally,

wateringperiodsshouldnotbemorethan12h.

Maizeisnottolerantofwaterlogging.Rootactivityisrestrictedbecauseoflackofoxygen,

andNlossesthroughdenitrificationandleachingcanbesignificant.Therearetwostages

ofgrowthwhenwaterloggingismostdamaging.Thefirstistheseedlingstagepriorto

thedevelopmentofsecondaryroots.Atthisstage,cropwateruseislow,resultingin

thesoildryingslowly.Anymarginalnutritionaldeficienciesareexacerbated,inparticular

zincdeficiency.Croprecoveryisslow,andcommonly,cropsnever‘catchup’fromearly

waterloggingsetbacks.Thesecondistheperiodfromtassellingtosilking,whenthecrop

ishighlysensitivetobothreductioninwateruptakeandinterruptionintheflowofnutrients.

Whenfurrowirrigating,anirrigationeventisusuallytimedjustpriortotassellingtoallow

timeforthefieldtoreturntoidealconditionsforthiscriticalperiod.28

Timing the last irrigation

Timingofthefinalirrigationneedstotakeintoaccountthecropstage,soiltypeand

plant-availablewatercapacity.Asgrainmaturityprogresses,maizebecomeslesssensitive

tomoisturestress,allowingthelastirrigationtobetimedtodrydownthesoilprofilein

preparationforharvest.However,timingofthelastirrigationwillalsodependonwhether

thecropisdestinedforasilageorgrainmarket.

Forgraincrops,thelastirrigationshouldbetimedtoensuremoistureisavailableuntilthe

grainisphysiologicallymature,asindicatedby‘blacklayer’formationongrain(milkline

scoreof5).Maizegenerallyreachesphysiologicalmaturity2weeksafterthefulldentstage,

andthecropwillusuallyrequireatleast60mmofwatertoreachthis.Inheavierclaysoils,

thenecessarymoisturecanbeheldin~30cmofmoistsoilandthefinalirrigationcanbe

stoppedupto4–5daysafterearlydent.However,becauseofthelimitedmoisture-holding







December 2014



capacityofsand-texturedsoils,irrigationmaynotbeabletobestoppeduntilaweekafter

full dent. 29

Itisimperativetoschedulethefinalirrigationbasedonknowledgeofthewater-holding

capacityandactualdepthandavailabilityofmoistureinthepaddock,asprovidedbydata

loggers,topreventwastageofwateroryieldtruncation.30

Silagecropsshouldbeharvested10–14daysearlierthangraincrops,whenthemilkline

scoreis2.5.BecauseofthehigherdailywateruseinearlyFebruary,timingthelastirrigation

onlyafewdaysearlieratearlydenting(about3weeksaftersilking)willresultinadeficitof

~90mmbythetimea2.5milklinescoreisreached. 31

Scheduling supplementary irrigation

Ifthereisreducedirrigationwateravailableoraforecastofinsufficientrainfall,thenyield

targetsformaizemayneedtobereducedandsupplementaryirrigationusedratherthan

fullirrigation.Theyieldofthesecropsisessentiallywater-limitedbutyieldcanbefarhigher

thandrylandaloneifmanagedwell.Thealternativeistoreducetheareacroppedanduse

availablewatertofullyirrigate.Thechoicebetweenthesetwostrategieswilldependon

individualfarmgrossmargins,alternativerotationcrops,paddockhistoryandcontracting

arrangements.

Insupplementarysituations,thefirstirrigationshouldbetimedpriortotasseling.Tasselling

generallyoccurs7–10dayspriortosilking.Whenmaizeplantsaremoisture-stressed

leadingintotasselling,thedevelopmentofsilkslowerontheplantmaybeslowerthan

usual,whichcanresultinpollenbeingshedandwastedbeforethesilksemerge,leading

toverypoorkernelset.Firstirrigationjustpriortotasselling(~8weeksafterplanting)will

usuallyofferthegreatestreturn.Iffurtherirrigationsarepossible,theyshouldbeapplied

duringthesilking(R1)andblister(R2)stages.Preferably,irrigationshouldbecontinueduntil

theendofthedoughstagetopreventwilting,butbecausestresslateintheseasonhas

theleastimpactofyield,irrigationsfromdentstagetomaturityarenotascritical.Itshould

berememberedthathighWUEisobtainedonlywhencropsarefullywatered.Maizeuses

250–300mmofwaterbeforeanyyieldisproduced. 32





i More information

Optimisingmaize

yieldunder irrigation.

GRDCUpdatePapers

September 2008.

Crop guide, 2012

season.DuPontPioneer.


growers’workshop.

Pioneer Hi-Bred

Australia.

CJBirchet al.(2003)

Agronomyofmaize


andprospect.In

5thAustralianMaize

Conference.










http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2008/09/OPTIMISING-MAIZE-YIELD-UNDER-IRRIGATION




http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/BROCHURE_SummerCrops2012.pdf

http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/BROCHURE_SummerCrops2012.pdf













December 2014



1.7 Optimising maize yield under irrigation

Optimisingmaizeyieldunderirrigationrequiresthecorrectcombinationofcropgenetics,

cropmanagementandenvironmentalfactors.Toproducemaximumyield,cropET

requirementsneedtobemetbyacombinationofstoredsoilwater,in-croprainfalland

irrigation.CropETisthecombinationofwaterthatgoesthroughtheplant(transpiration)

andwaterthatislostfromthesoilsurface(evaporation).CropETmainlydependson

weatherconditions,stageofcropgrowth,andavailablesoilwater.ETchangesfromseason

toseasonandfromdaytoday.

Cropgeneticsrelatestochoosingvarietiesthatareadaptedtolocalconditionsandhave

adequateyieldpotential.Cropmanagementrelatestoprovidingthecropwithgrowing

conditionsthatareascloseaspossibletooptimal.Thisincludesavarietyofpractices

suchaslandpreparation,sowing,soilnutrition,pest(insects,disease,andweeds)control

andirrigation.Thesepracticescansignificantlyinfluencecropyield,eitherindividuallyor

incombination,andcangenerallybemanaged,dependingonfarmer’sskills,knowledge

andresources.Environmentalfactors,suchastheweather,soilandwaterquality,cannot

alwaysbetotallycontrolled.

Assumingthatgenetics,cropmanagement,andenvironmentalfactorsareproperly

managed,optimisingmaizeyieldunderirrigationrequiresprovidingthecropwithenough

watertomeetcropETrequirementsatalltimes.Therefore,bothcorrectamountandtiming

ofwaterapplicationsarecritical.Considerableresearchhasshownthatmaizeyieldis

linearlyrelatedtocropET;researchershavereportedlinearrelationshipsbetweenmaizeET

andyield.Forexample,Figure2showstherelationshipadaptedfromtwofieldexperiments

inNebraskareportedbyPayeroet al.(2008a, 2008b).Atthatlocation,~270mmofET

wasrequiredtostartproducinggrainyield.Thisincludeswaterneededjusttoproduce

vegetativegrowthandwaterthatwaslostbysoilevaporationanddidnotcontributeto

grainyield.Theslopeofthelineindicatesthatafterthefirstyieldunitwasproduced,each

mmofETproducedanadditional0.0317Mg/ha(=31.7kg/ha)ofgrain,and~663mmof

ETwasrequiredtoproducemaximumyield.Theresultssuggestthatstressatanytime

duringthegrowingperiodwillreduceETand,therefore,willreduceyield.Themagnitudeof

theyieldreductiondependsontheseverity,timing,anddurationofwaterstress.

Figure 2:

Evapotranspiration (mm)

Yie

ld (M

g/h

a)

0 100 200 400 700

14

12

10

8

6

0300 500 600

4

2

y = 0.0317x - 8.5199R2 = 0.8385

Relationship between maize yield and seasonal crop evapotranspiration obtained at Nebraska during 2005 and 2006.

cusin




December 2014



AlthoughtherelationshipbetweenmaizeyieldandETisrelativelyconsistentforaparticular

location,maizeyieldresponsetoirrigationisveryvariableandchangeswithlocationand

season,asshowninFigure3,froma5-yearexperimentconductedinNebraska(Payeroet

al.2006).Inthisexperiment,fourirrigationtreatmentswerecomparedduring1992–96:no

irrigation(Dryland),oneirrigationpriortotasselformation(Early),oneirrigationduringthe

silkstage(Late),andirrigationfollowingfarmers’practices(Farmer).TheFarmertreatment

wasfullyirrigatedandalwaysresultedinmoreirrigation.

In3of5years,therewasnoresponsetoirrigation,becausethosewerewetyears.

Nonetheless,theFarmertreatmentstillreceived~500mmofirrigation.Duringthetwo

driestyears(1994and1995),therewasaresponsetoirrigation.In1994,thedeficit-

irrigationtreatmentsreceivedabout130mmofirrigationandproduced~90%ofnormalised

yield,whereastheFarmertreatmentreceived500mmandproducedonlyanadditional

10%increaseinyield.In1995,thedeficit-irrigationtreatmentsreceived~110mmof

irrigationandproduced70%ofthenormalisedyield,whereastheFarmertreatment

received700mmtogettheadditional30%increaseinyield.Thisillustratesthatmore

irrigationdoesnotalwaysresultinadditionalyield,andthatsometimes,fullyieldcanbe

obtainedwithnoirrigation.

Figure 3:

0

20

40

60

80

100

120

0 200100 300 400 500 600 700 800

Seasonal irrigation applied (mm)

No

rmal

ised

yie

ld (%

)

19921993199419951996

Relationship between seasonal irrigation and normalized yield for surface-irrigated maize in Nebraska (from Payero et al. 2006).

1.7.1 How much water is needed to optimise maize yield?

CropETdependsmainlyonweatherconditions,cropcover(cropdevelopmentstageand

density),andavailablesoilwater,andthereforevariesdailyduringthegrowingseason

andwithlocation.Forexample,Figure4showsdailymaizeETmeasuredwithaneddy

covariancesysteminNebraska(Payeroet al. 2008c);maizeETincreasedfromemergence,

peakedatabout8.5mm/dayatabout90daysafteremergenceandthensteadily

decreased.TheshapeandmagnitudeoftheETcurvewillbedifferentforeachlocation

andeachseason.Day-to-dayvariabilityinETmainlyreflectsdailychangesinweather

conditions.




December 2014



Figure 4:

0

4

3

2

1

5

6

7

8

9

0 4020 60 80 100 120 180160140 200

Days from emergence

Eva

po

tran

spir

atio

n (m

m/d

ay)

Crop evapotranspiration for maize measured at North Platte, Nebraska, during 2001, using an eddy covariance system (from Payero et al. 2008c).

DailyvaluesofmaizeET(ETc,mm/day)foragivenlocationcanbeestimatedfromweather

dataas:

ETc=ETo×Kc(1)

whereEToisgrassreferenceevapotranspiration(mm/day),andKciscropcoefficient.ETo

canbecalculatedfromweatherdatausingavarietyofmethods.LocallytestedKcvalues

fordifferentcropsarelackinginAustralia,butvalueshavebeensuggestedfromempirical

studiesaroundtheworld(Allenet al.1998)thatcanbeusedtoobtainagoodestimationof

ETc.

Figure5presentslong-termaveragedailyETovaluesfordifferentlocationsinAustralia

reportedbySILO,whichwerecalculatedfromweatherdata.Figure6showsthecrop

coefficient(Kc)curvedevelopedfrominternationalvaluessuggestedbyAllenet al.(1998),

andFigure7theaveragedailyETcforeachlocation,calculatedwithEqn1usingthe

sowingdatesshowninTable5.DailycumulativeandseasonalETcvaluesareshown

inFigures8and9,respectively.Figures7and8showverysimilardailyandcumulative

ETearlyintheseasonforalllocations.However,considerabledifferencesinETbegin

toshowat~70daysaftersowing.Thesegraphsweregeneratedtoguidefarmersasto

themagnitudeandtimingofcropwateruse.Aswithanymodellingapproach,thereare

uncertainties,including:

• yearlyanddailydeviationsinweatherconditionsfromthelong-termaverage

• variationsinsowingdates

• differencesamongcropvarieties,especiallyrelatedtoseasonlength

• lackoflocallydeterminedKcvalues

• uncertaintiesinETobecauseSILOusesafixedvalueforwindspeedof2m/s

i More information

Maize module. APSIM

Initiative.

Multipleseasonmaize

simulations.APSIM

Initiative.


https://www.longpaddock.qld.gov.au/silo/

http://www.apsim.info/Documentation/Model,CropandSoil/CropModuleDocumentation/Maize.aspx

http://www.apsim.info/Documentation/Model,CropandSoil/CropModuleDocumentation/Maize.aspx

http://www.apsim.info/Documentation/TrainingManualsandResources/APSIMTraining(SIMLESA)/Multipleseasonmaizesimulations.aspx





December 2014



Figure 5:

ETo

(mm

/d)

Days from emergence

8.0

7.0

6.0

5.0

4.0

3.0

2.0

1.0

0.00 4020 60 80 100 120 180160140 200

BrooksteadDalbyGoondiwindiSt GeorgeEmerald

Grass reference evapotranspiration (ETo) for different locations in Australia.

Figure 6:

Days after sowing

Kc

0 30 60 150

1.4

1.2

1.0

0.8

0.6

0.090 120

0.4

0.2

Crop coefficient (Kc) curve for maize (Allen et al. 1998).

Figure 7:

ETo

(mm

/d)

Days after sowing

8.0

7.0

6.0

5.0

4.0

3.0

2.0

1.0

0.00 4020 60 80 100 120 180160140 200


Average daily maize evapotranspiration (ETc) calculated for different locations.




December 2014



Table 5: Maize sowing dates for each location

Location Maize sowing date

Brookstead 15 Sept.

Dalby 15 Sept.

Goondiwindi 1 Sept.

St. George 20 Aug.

Emerald 15 Aug.

Figure 8:

Cum

ulat

ive

evap

otr

ansp

irat

ion

(mm

)

Days after sowing

1000

900

800

700

600

500

400

300

200

100

00 4020 60 80 100 120 180160140 200


Average daily maize cumulative evapotranspiration (ETc) calculated for different locations.

Figure 9:

BrooksteadDalby

GoondiwindiSt George

Emerald

Sea

sona

l ETc

(mm

)

800

780

760

740

720

600

640

660

680

700

620

676689

746761

734

Average seasonal maize evapotranspiration (ETc) calculated for different locations.

Figures7–9showthatmaizeETrequirementstoproducemaximumyieldcanvary

considerablywithlocation,withadifferenceinseasonalETof85mmbetweenBookstead

andSt.George.ApplyingmorewaterthantheETrequirementsofthecropwillnot

increaseyields,andmayreduceyieldsbecauseofproblemssuchasnitrateleachingand

waterlogging.IrrigationisneededonlytosupplementETrequirementsthatcannotbemet

bywaterstoredinthesoilprofileatsowingandbyeffectivein-croprainfall.Itistherefore

criticaltohaveameansofmeasuringorestimatingsoilwatercontentduringtheseasonto

determinewhenirrigationisneededandhowmuch(ifany).




December 2014



1.7.2 Some local dataToillustratetheirrigatedmaizeyieldsthatcanbeobtainedlocallyandhowmuchin-crop

rainandirrigationwaterwasrequiredtoobtainthoseyields,datawereacquiredfromcrop

competitionsconductedontheDarlingDownsandtheLockyerValley.Theaccuracyofthe

irrigationdatafromthisdatasetisvariableandmeasuredquantitieswererarelyprovided.

Estimatesofappliedirrigationwater,whenonlynumberofirrigationswasgiven,werebased

ontheassumptionthatonefloodirrigationwasequalto1ML/ha.Dataonstoredsoilwater

wereseldomcollectedandarenotincluded;however,storedsoilwaterisanimportant

sourceofwatertomeetcropwaterrequirementsandcanbesignificant,especiallyinthe

heavysoilspredominantontheDarlingDowns.

Irrigatedmaizedatafromthecropcompetitionsfrom1987to2005summarisedinTable6

showthatmaizeyieldsaveraged11.5t/haduringthatperiod,butmaximumyieldsranged

from11.0to15.6t/ha.Thoseyieldswereproducedwithseasonalirrigationdepthsranging

from200to427mm,withanaverageof317mm(100mm=1ML/ha).In-croprainfall

rangedfrom203to672mm,withanaverageof440mm.Rain+irrigationrangedfrom

503to931mm,withanaverageof767mm.Table6alsoshowstheyieldperunitirrigation

andperunitofrain+irrigation.AlthoughdatainTable6donottelluswhetherthoseyields

couldbeobtainedwithlesswater(thatwouldrequiremorein-depthanalyses),theyprovide

anindicationofactualvaluesreportedbyrealproducers.33

Table 6: Irrigated maize data summary from crop competitions on the Darling Downs and the Lockyer Valley

Year Yield (t/ha) Irrig (I) Rain (R) R + I Yield/I Yield/(R+I)

Max. Min. Av. (mm) (kg/ha.mm)

1987 11.1 8.3 9.6 344 452 796 28.0 12.1

1988 13.9 8.5 11.0 343 588 931 32.2 11.9

1989 11.0 8.5 10.0 300 203 503 33.4 19.9

1990 12.7 9.7 11.6 340 543 883 34.2 13.2

1991 11.7 8.3 10.2 427 360 787 23.8 12.9

1992 13.4 9.1 11.3 304 591 895 37.0 12.6

1993 13.5 7.5 10.7 300 248 548 35.7 19.6

1994 11.4 8.6 9.9 358 525 883 27.7 11.3

1995 12.0 8.7 10.4 340 386 726 30.5 14.3

1996 13.1 11.1 11.9 225 672 897 52.8 13.3

1997 14.4 11.1 12.5 283 261 544 44.2 23.0

1998 13.2 8.5 10.4 313 374 686 33.2 15.1

1999 14.3 11.8 12.8 375 517 892 34.2 14.4

2000 15.3 10.3 12.8 256 50.2

2001 15.1 10.3 13.4 375 35.6

2002 14.4 10.4 12.7 327 38.9

2003 13.1 11.0 12.0 337 35.8

2004 13.8 8.8 11.6 200 57.8

2005 15.6 11.9 13.3 275 48.3

Av. 13.3 9.6 11.5 317 440 767 37.6 14.9

Min. 11.0 7.5 9.6 200 203 503 23.8 11.3

Max. 15.6 11.9 13.4 427 672 931 57.8 23.0

33 GRDC(2008)Optimisingmaizeyieldunderirrigation.GRDCUpdatePapersSeptember2008,http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2008/09/OPTIMISING-MAIZE-YIELD-UNDER-IRRIGATION







December 2014



1.7.3 Irrigation in QueenslandMaizerequires4–8mL/haofirrigationdependingonlocation,seasonalrainfalland

temperatureconditions,andirrigationefficiency.Moistureuseandavailabilityshouldbe

monitoredusingsoil-moisturemonitoringtools.Consultlocalcropconsultantsandirrigation

suppliersfortheavailabilityofsuchtools.

Ideally,drylandmaizeshouldbeplantedonafullprofileofsoilmoisture.Ifmoistureis

marginal,considerplantingsorghuminstead.

Forirrigatedmaize,thelandshouldbepre-irrigatedbeforethemaizeisplanted.

Mildwaterdeficitsthroughoutthevegetativegrowthstagesreduceleafarea.Severe

moisturedeficitsreduceleafnumber.Bothreducetheplants’photosyntheticabilityand

affectgrainyield.Becausefloweringisthecriticalstagefordeterminingfinalcropyield,

irrigatedcropsshouldbewateredwellduringfloweringandthroughtophysiological

maturity.Itmaybenecessarytoirrigatewithfloodirrigationeveryweekinhot,dryweather,

ormoreoftenwithanoverheadsprinklersystem.Evenifearlysoilmoistureatplantinghas

beenadequatetoproducemaximumleafarea,moisturestressatlaterstagescausesleaf

senescenceand,therefore,depressionofyield.

Growersmonitoringirrigationinmaizecropsshouldbeawarethattheeffectiverooting

depthofmaizeis100cm.34

1.8 Yield and targets

Althoughmaizeisasummercrop,itisnotheatlovinglikecotton(anaridplant).Maizeis

asubtropicalplantratherthanatemperateplant,andthereforeprefersmilderconditions

withplentyofsunshinewithoutexcessiveheat(Figure10).Aswellasbeingtemperature-

sensitive,themaizeplantisalsosensitivetodaylength.

Maizeisa‘shortday’plant;asthedaylength(photoperiod)shortens,sodoesthetime

fromgerminationtoinitiationoffloralparts,althoughconsiderablevariationforphotoperiod

sensitivityexistsinthegermplasm.

34 DAFF(2012)Nutrition,irrigationandweedsformaize.DepartmentofAgriculture,FisheriesandForestryQueensland,https://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/nutrition-irrigtion

i More information

N.Baxter(2013)Irrigated

maizebuildsbusiness

resilience.GRDCGround

CoverIssue106.


https://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/nutrition-irrigtion


http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-106-Sept-Oct-2013/Irrigated-maize-builds-business-resilience






December 2014



Figure 10: Maize prefers milder conditions with plenty of sunshine without excessive heat. (Photo: Pioneer)

Criticaldaylengthappearstobe14.5–15h.Thismeansthatmaizegrownbetweenlatitudes

23°S(~50kmnorthoftheTropicofCapricorn)and23°N(roughlytheTropicofCancer)

doesnotexperiencedayslongenoughtomaximiseyields.

Asaresult,thesamehybridplantedsouthoftheTropicofCapricorncomparedwith

plantinginthetropicalnorthwilltakelongertoflower,willhavemoreleavesandwillbe

taller.

Thebestmaizehybridshaveageneticyieldpotentialof~40t/haofgrain.Thispotential

variesaccordingtoclimate,timeofplanting,plantpopulations,soiltypesandpH,water

management,nutrition,weedcontrol,presenceofdiseaseandotherenvironmentalfactors.

TheyieldpotentialinAustraliais~20–22t/habecauseoftheharshclimate.Excessive

daytimetemperaturesof40°C+coupledwithnight-timetemperaturesof28°–30°Cfor

periodsofupto10daysduringthecrucialpollination–seedsetperioddramaticallyreduce

yields.Withthisexcessiveheat,italsostretchesresourcestryingtokeepmoistureuptothe

cropsatsuchacriticaltime.

ThestagesofgrainfillinmaizearedepictedinFigure11:

1. Pollination.Stresswillreducethenumberofgrainssetbutnotgrainquality.

2. Celldivision.Stresswillpreventpropercelldivisionandcanreducegrainsizebutnot

proteinorstarchcomponents.Bushelweightcanbeaffectedinsomegenotypes.

3. Starchdeposition.Stresswillreducestarchdepositionandcanchangetheprotein/

starchratioandseriouslyaffectdensityandmillingqualities.

4. Proteindeposition.Stressatthisstagehasthegreatesteffectongraindensity

andmillability.Thestorageproteinsarelaiddownlateingrainfillandtheyactasa

‘superglue’tobindthestarchgranulesintoaverydensematrix.TheroleofNis

criticalinlategrainfilltomakeorbreak‘grits’maize,oftherightgenotype:

lowN=lowprotein(<8.5%)=starchtype;highN=highprotein(8.5–10%)=grit

type.




December 2014



Sunlightprovidestheenergyneededtoproducestarch.Inassociationwithgoodsoil

structure,whichallowsrapidearlyrootgrowth,adeepanddenserootsystemwillhelp

ensurehighyields.Rootgrowthwillberestrictedinareaswithdensesubsoils,hardsetting

topsoils,highwatertablesorsalinity.

Figure 11:

Stage VE V2Emergence

Planting

Days

Growth stages

The stages of grain fill in corn

-7 0

1 2

65 days

3 4 5 6

7 21 35 46 56 63 105 130

2 leavesfully

emerged

8 leavesfully

emerged

12 leaves 16 leaves Pollination20 leaves

5 leavesfully

emergedTassel and ear initiation

V5 V8 V12 V16 R1 HARVESTPM

Pollination

Cell division

Starch deposition

Protein deposition

Drydown

The stages of grainfill in maize. (Source: Pacific Seeds)

1.8.1 Seasonal outlookQueenslandAllianceforAgriculture&FoodInnovation(QAAFI)producesregular,seasonal

outlooksforsummercropproducers.Thesehigh-valuereportsarewritteninaneasy-to-

readstyleandarefree.Formoreinformation,visitSeasonalCropOutlook(Sorghum).

Fortipsonunderstandingweatherandclimatedrivers,includingtheSouthernOscillation

Index(SOI),visittheClimate Kelpiewebsite.Casestudiesof37farmersacrossAustralia

recruitedas‘ClimateChampions’aspartoftheManagingClimateVariabilityR&DProgram

canalsobeaccessedatthewebsite.

AustralianCliMateisasuiteofclimateanalysistoolsdeliveredontheweb,iPhone,iPad

andiPodTouchdevices.CliMateallowsyoutointerrogateclimaterecordstoaskquestions

relatingtorainfall,temperature,radiation,andderivedvariablessuchasheatsums,soil

waterandsoilnitrate,andwellasElNiñoSouthernOscillationstatus.Itisdesignedfor

decisionmakerssuchasfarmerswhosebusinessesrelyontheweather.

DownloadfromtheAppleiTunesstoreat:https://itunes.apple.com/au/app/australian-

climate/id582572607?mt=8orvisitAustralianCliMate.

OneoftheCliMatetools,‘Season’s progress?’,useslong-term(1949topresent)weather

recordstoassessprogressofthecurrentseason(rainfall,temperature,heatsumsand

radiation)comparedwiththeaverageandwithallyears. Itexploresthereadilyavailable

i More information

BureauofMeteorology.

Sunshine:averagedaily

sunshinehours.

i More information

ElNiño-Southern

Oscillation.

Managing Climate

VariabilityClimate

Championprogram.


http://www.qaafi.uq.edu.au/sorghum-outlook

http://www.climatekelpie.com.au/

https://itunes.apple.com/au/app/australian-climate/id582572607?mt=8

https://itunes.apple.com/au/app/australian-climate/id582572607?mt=8

http://www.australianclimate.net.au

http://www.bom.gov.au/watl/sunshine/



http://www.climatekelpie.com.au/understand-climate/weather-and-climate-drivers/queensland#ElNino

http://www.climatekelpie.com.au/understand-climate/weather-and-climate-drivers/queensland#ElNino

http://www.climatekelpie.com.au/ask-a-farmer/climate-champion-program





December 2014



weatherdata,comparesthecurrentseasonwiththelong-termaverage,andgraphically

presentsthespreadofexperiencefrompreviousseasons.

Cropprogressandexpectationsareinfluencedbyrainfall,temperatureandradiation

sinceplanting.Season’s progress?providesanobjectiveassessmentbasedonlong-term

records:

• Howisthecropdevelopingcomparedtopreviousseasons,basedonheatsum?

• Isthereanyreasonwhymycropisnotdoingaswellasusual,becauseofbelow-

averagerainfallorradiation?

• Basedontheseason’sprogress(andstartingconditionsfromHowWet–N?),shouldI

adjustinputs?

Forinputs,Season’s progress?asksfortheweathervariabletobeexplored(rainfall,

averagedailytemperature,radiation,heatsumwithbasetemperaturesof0,5,10,15and

20°C),astartmonthandaduration.

Asoutputs,textandtwographicalpresentationsareusedtoshowthecurrentseasonin

thecontextoftheaverageandallyears.Departuresfromtheaverageareshowninafire-

riskchartasthedeparturefromtheaverageinunitsofstandarddeviation.35

TheBureauofMeteorologyhasmovedfromastatistics-basedtoaphysics-based

(dynamical)modelforitsseasonalclimateoutlooks.Thenewsystemhasbetteroverallskill,

isreliable,allowsforincrementalimprovementsinskillovertime,andprovidesaframework

fornewoutlookservicesincludingmulti-week/ormonthlyoutlooksandtheforecastingof

additionalclimatevariables.36

1.8.2 Water use efficiencyMaizeisoneofthehighestyieldingcropsforbothdrymatterandgrainproductionper

hectare.Consequently,ithasahighwaterrequirement.Italsoisoneofthemostwater-

efficientcropsbecauseitproducesalargeamountofgrainanddrymatterpermillimetre

ofwater.However,itmusthaveadequatewateravailabletoachievethispotential.Atthe

sametime,weshouldnotunderestimatetheyieldlossesthatcanoccurfromtoomuch

water or waterlogging.

Mostdamageoccursinveryyoungcropswhentheyaredevelopingtheirmassiveroot

system.Waterloggingisaresultofbadlydrainedsoilsorfieldsthatarepoorlydeveloped,

excessiverainfallorirrigation.Toomuchwaterintheroot-zonecanbeasdetrimentalasnot

enoughwaterbeingavailabletotheplant.

Yieldreductionsofupto50%canresultifmaizeiswiltedfor4daysattheendofthe

pollinationperiod(Table7).Eveninthedoughstage,4consecutivedaysofwiltingcan

reduceyieldby40%.Ontheotherhand,4daysofwiltingatleastaweekpriortotasselling

causedonlyhada10%reductioninyield.

35 AustralianCliMate—Climatetoolsfordecisionmakers,www.australianclimate.net.au

36 JSabburg,GAllen(2013)Seasonalclimateoutlookimprovementschangesfromhistoricaltorealtimedata.GRDCUpdatePapers18July2013,http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/07/Seasonal-climate-outlook-improvements-changes-from-historical-to-real-time-data

i More information

JSabburg,GAllen

(2013)Seasonalclimate

outlookimprovements

changesfromhistorical

to real time data. GRDC

UpdatePapers.

AustralianCliMate.



http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/07/Seasonal-climate-outlook-improvements-changes-from-historical-to-real-time-data









December 2014



Maizeismoisture-stressedwhentheedgeoftheleafstartstocurlinwards.Underhot,low-

humidityconditions,stresssymptomsmayoccurdespiteadequatesoilmoistureandbefore

therefillpoint(thepointbelowwhichthecropmayexperienceyieldlossesduetomoisture

stress)hasbeenreached.

AswithNandphosphorus(P),themaizeplantusesthemajority(70%)ofitsmoisture

requirement3weekseithersideoftasselling.

Maizehasamuchlongergrain-fillingperiodthancropssuchassorghum,roughlyone-third

longer,hencetheimportanceofwatermanagementduringthisperiod(Figure12).

Ahigh-yieldingmaizecropwillbeverywater-efficient;totalwateruseefficiencyshouldbe

22–30kg/mmforwell-managedcrops.Thetotalamountofwaterrequiredwilldependon

theenvironment.

Themaincontributorstowaterusearewindspeed,temperatureandhumidity.Wateruse

canbemanipulatedinsomelocationsthroughhybridselectionandplantingrate.

Dailywaterusevariesduringtheseasondependingongrowthstageandweather

conditions.Thecrop’sabilitytotakeupwaterincreasesasthecanopydevelops,peakingat

thesilkingstage.

Weatherconditionsthatarehot,dryandsunnywillincreasethecrop’swaterrequirement.

Talleranddensercropswillusemorewaterthanshortercropsbecausetheyinterceptmore

sunlightandtheyaremoreexposedtowind.Itisimportanttohaveknowledgeofsoilwater

depletionandtheabilityofyoursoiltoholdwater.

Table 7: Effects of moisture stress on maize a various stages

Earlygrowthstage Affectsleafcellenlargementresultinginsmallerleaves,ashortercanopyandareductioninpotentialyield.

Pollenshed Severemoisturestressatpollinationwillgivepoorpollinationandreducedkerneldevelopment.Yieldlossesatthisstagecanbeashighas5%perday.

Silking/fertilisation Duringthis3-weekperiodmaximumwaterusageoccursandastressduringtheearlypartofthisperiodwillaffectkernelnumbers.Stressduringthelatterpartwillaffectkernelweight.

Grainfill Stressatthispointwillhastenmaturity,reducingphotosynthesisandstarchproduction.Afteraperiodofseverewaterstress,themaizeplantmaytakeseveraldaystorecoverdespiteplentifulsoilmoisture.

Pre-physiological Thelastwateringisimportantforfinalkernelsizeandthereforeweight;maturityespeciallyforproducersgrowingcontractedgritmaize.




December 2014



Figure 12:

0.4

0.3

0.2

inch

es

% y

ield

red

ucti

on

0.1

0.0 100

60

40

30

10

20

20

0

emergence full tassel

critical stagedaily water use yield reduction due to moisture stress

pollination

soft dough

mature emergence full tassel

pollination

soft dough

mature

Moisture management in maize.

Amaizecropwillextractonlyaportionofavailablewaterbeforemoisturestresssetsin.Often

thesoilprofilemaynotbefullywetduetoinsufficientwaterapplied,restrictedinfiltrationor

excessiverunoff.

Itisimportanttobaseirrigationperiodsor‘scheduling’ontheallowabledepletionorallowable

waterdeficitatvariousstagesoftheseason.Thisisoftencalledthe‘refillpoint’.Allowable

depletionisthepointbelowwhichthecropmayexperienceyieldlossesduetomoisturestress.

Asrootsarenotfullydevelopedpriortotasselling,itissuggestedthatdepletiondoesnot

exceed40%.Duringtassellingandgrainfill,thisfigurecanriseto50%unlessextreme

temperaturesprevail.

Depletionatmaturitycanbeupto75%undermoderateconditions.

AroughguideisthatanirrigatedmaizecropinsouthernNSW–Victoriawillreceive10–12

wateringsduringitslife(longerdays,fewercloudydaysandwater-holdingcapacitylowerthanin

northernNewSouthWales).

Duringpeakwateruse,wateringmaytakeplaceevery7–10days,dependingontemperatures.

Ontheotherhand,innorthernNSW–Queensland,5–7wateringsareusuallyrequiredwith

schedulingevery10–14days,againdependingontemperatures.37

Budgetscanbefoundthroughthestatedepartmentsandcanthenbetailoredforafarmer’s

ownsituation.

1.8.3 Nitrogen-use efficiencyBecausemaizeisabigproducerofdrymatter,itisalsoabiguserofnutrients,whichmany

Australiansoilsarenotcapableofsupplyingwithouttheadditionoffertilisers.Soilsshouldbe

regularlytestedsoyouareawareofthenutrientstatus(bothmacro-andmicro-nutrients),pH

and organic matter.

Onceyouhaveanalysedsoiltestresults,youcanplanafertiliserprogrambasedonavailable

nutrientsandmostimportantlyyourbudgetorexpectedyield.Remember,ifgrowingmaizefor

silageyouwillneedaslightlydifferentfertiliserprogramthanwhatyouwouldforgrain.


i More information

CJBirchet al.(2003)

Agronomyofmaize


andprospect.In

5thAustralianMaize

Conference.


au/__data/assets/pdf_

file/0003/175908/East-

dryland-maize-12-13.pdf

http://www.nt.gov.au/d/

Content/File/p/Tech_Bull/

TB326.pdf#search=

%22maize%22

https://publications.qld.

gov.au/dataset/agbiz-

tools-plants-field-crops-

and-pastures










http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0003/175908/East-dryland-maize-12-13.pdf




http://www.nt.gov.au/d/Content/File/p/Tech_Bull/TB326.pdf#search=%22maize%22




https://publications.qld.gov.au/dataset/agbiz-tools-plants-field-crops-and-pastures






December 2014



ThethreeprimarynutrientsrequiredforamaizecropareN,Pandpotassium(K),which

represent83%oftotalnutrients.

Thesecondarynutrientssulfur,calciumandmagnesiumcompriseanother16%,which

meansthemicronutrientsonlyrepresent1%ofthetotalnutrientuptake.

MaizetakesupthelargemajorityofitsKbysilkingbutrequiresasupplyofNandPbeyond

grainfill.Theaccumulationofwater,N,PandKisrapidintheearlystagesofgrowthbeyond

the4–5-weekperiod.38

1.8.4 Double-crop optionsNortherngraingrowersthinkingofdouble-croppingshouldbewellpreparedinspringand

shouldaddressquestionsofsoilnutrition,wateravailabilityandweedpressure.

Mostimportantiscropselectionandcheckingforanypotentialissuesfromresidualherbicides

thatmayhavebeenusedearlierintheseason.

Graingrowerswillalsoneedtoconsiderwhichweedsarelikelytobepresentoversummerso

theycanchooseacropthatwillallowthecorrectherbicide-chemistrygroupstobeusedaspart

oftheirherbiciderotations.

Forexample,mungbeangrowerscanuseGroupAchemistryin-cropforgrassweedcontrol,

whereassorghumgrowerstacklingthesamegrassweedscanuseGroupKresidualherbicides.

Thisapproachwillallowgrowerstokeepontopofweedpressureswhileminimisingtheriskof

resistancedevelopingintheweedpopulation.

Sprayrigsshouldbecheckedtomakesureyouaregettingthegreatestefficiencyoutofthe

herbicideapplied.Ifthesprayrigisnotsetupproperly,thereisamuchsmallermarginforerror

whensprayinginspringandsummer,comparedwiththemoreforgivingconditionsinwinter.

Growersmustchecktheplant-availablewaterstoragecapacityintheirsoilssotheycanchoose

asuitablecroptype.Thisensuresthattheymakeaninformeddecisiononcropestablishment,

whichiscriticalforgrowingdrylandmaize.Agronomistsgenerallyrecommendafullprofileof

moisturebeforesowingdrylandmaizebecausethereisalimitedtimetoaccumulatesoilwaterin

adouble-cropperiod.Inaddition,limitedNismineralisedinadouble-cropperiod,solargeinputs

arerequiredtogrowmaizecrop.Itispreferabletodouble-cropoutofmaizeintoapulsecrop.

Deepsoiltestingisalsoencouragedsothatyoucanmakeappropriatedecisionsaboutthe

amountsandtypesoffertilisertobeapplied.ApplyingNascloseaspossibletothetimethe

plantneedsitwillalsohelpmaximiseuptakeandminimisewastage.

Newtrialsco-fundedbytheGrainsResearchandDevelopmentCorporation(GRDC)are

highlightingtheimportanceofpre-seasonsoiltestingtoquantifyprofilemineralNreserves.

TheresearchisbeingconductedbyQAAFIPrincipalResearchFellowDrMikeBell,whois

examiningtheeffectofNfertiliserapplicationtime—pre-planting,atplantingandincrop/

sidedressing—andproducttype(ureaaloneorinvaryingformulations).


i More information

D Rodriguez et al.(2013)

Relay-croppingextends

cropping window.

GroundCoverIssue104.

http://www.

irrigatedcroppingcouncil.

com.au/documents_

research/publications/

ICF_double_cropping_

booklet.pdf

Wateruseefficiency.

Cropyieldsandglobal

foodsecurity.ACIAR.

Considerationsfor

double-cropping

cornfollowinghayin

Pennsylvania.Penn

State.

Makingcornafterwheat

work.TheFarmPress

2009.

KJohnson.Under

exploited double crop

opportunities.Purdue

University.




http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-104-May-June-2013/Relay-cropping-extends-cropping-window




http://www.irrigatedcroppingcouncil.com.au/documents_research/publications/ICF_double_cropping_booklet.pdf






http://aciar.gov.au/files/mn-158/s11_2-water-use-efficiency.html



http://extension.psu.edu/plants/crops/grains/corn/production/considerations-for-double-cropping-corn-following-hay-in-pennsylvania





http://deltafarmpress.com/corn/making-corn-after-wheat-work



http://www.agry.purdue.edu/forageday/underexploited.pdf






December 2014



ItishopedthatthedatawillenablegrowerstoadjusttheirfertiliserNratesmoreaccurately

tofittheircircumstances.39

1.8.5 What is relay cropping?Relaycroppingmeanssowingasecondcropintoastandingcropbeforethefirstcropis

harvested.Thiscanbeachievedquiteaccuratelyusingcontrolled-trafficequipment.

Forexample,amedium-quickmaturingmaizecrop(CRM110)sowninSeptemberatCecil

Plains,Queensland,willmaturebytheendofDecemberandbeharvested1–4months

later.Thislengthyperiodimpedesopportunitiesfordouble-croppingasummerlegumein

high-rainfallseasons(Figure13a).However,ifamungbeancropisrelay-plantedintothe

maizeatmaturitytherewouldbea43%chancethatthecropwouldreceive>250mmof

rainbetweenDecemberandMarch(Figure13b)andtherebyyieldanadditionalcropin

nearlyeverysecondyear.

Technologiestorelay-sowacropintoanexistingstandingcropareavailableforwheat–

mungbeanandsorghum–chickpeacombinations.

Researchersareinvestigatingtherequiredmachineryinnovationswiththemachinery

industrytodevelopandadaptequipmentforopportunisticrelayingofmaize–mungbean.40

Figure 13:

0

50

100

150

200

250

Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul0

5

10

15

20

25

30

Sun

shin

e (M

j/m

2 /d

ay)

Mo

nthl

y ra

infa

ll (m

m) Low yielding legume

grown under low rainfalland low radiation

MaizeMaize dryup period Legume

a.

0

50

100

150

200

250

Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul0

5

10

15

20

25

30

Sun

shin

e (M

j/m

2 /d

ay)

Mo

nthl

y ra

infa

ll (m

m) High yielding legume

grown under higher rainfall and radiation

Maize Legume

b.

Time course of rainfall and sunshine availability for crop growth and matching crop demand for resources in (a) single-cropping and (b) relay-cropping systems at Gatton, Queensland.

39 KBecker(2014)Plannowforsummerdoublecrop.GRDCMediaCentreOctober2014,http://www.grdc.com.au/media-centre/media-news/north/2014/10/plan-now-for-summer-double-crops

40 D Rodriguez et al.(2013)Relay-croppingextendscroppingwindow.GroundCoverIssue104,May2013.GRDC, http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-104-May-June-2013/Relay-cropping-extends-cropping-window

i More information

KBecker(2014)Plan

nowforsummerdouble

crop. GRDC Media

Centre.

Short-termprofits,long-

termpayback.Choosing

rotationcrops.GRDC

FactSheet.


pathstosuccessfor

Queenslandmaize

growers.GroundCover

Issue102.

LJenkins(2012)

Summercropoptions

forthecentralwest—

mungbeans&soybeans.

GRDCUpdatePapers.

Theme4. Advancing

profitablefarming

systems.GRDCProject

Summaries.


http://www.grdc.com.au/media-centre/media-news/north/2014/10/plan-now-for-summer-double-crops








http://www.grdc.com.au/Resources/Factsheets/2011/03/Choosing-Rotation-Crops-North









http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2012/04/Summer-crop-options-for-the-central-west-mungbeans-soybeans





http://www.grdc.com.au/Research-and-Development/Project-Summaries/Theme-4






December 2014



1.9 Relay cropping extends cropping window

1.9.1 Key points• Opportunistic‘relaycropping’couldbeanewtransformationalpracticeableto

squeezetwocropsintoasingleseason.

• Moderncontrolled-trafficandseedtechnologiesfacilitatethemechanisedmanagement

ofrelay-croparrangements.

• TrialsinQueenslandshowsignificantproductionandfinancialgainsfromopportunistic

cereal–legumerelaycropping.

Could the relay-cropping systems from the Argentine Pampas open a new frontier for the northern grains industry?

Figure 14: Twin-crop sowing: soybeans and sunflowers.

ItisbecomingclearthattheproductivitygainsrequiredforAustralianagriculturetoremain

competitiveandcontributetotheincreasingglobaldemandforfood,fibreandenergywill

notonlyneedsmallincrementalgainsinproductivity,butmayalsorequiretransformational

changestoexistingproductionsystems(Figure14).

Thechallengeforgrowersandresearchersistodevisenewcroppingsystemsor

‘breakthroughinnovations’thatsustainablyandsubstantiallyincreaseproductionwith

minimalrisk.

Australia’snortherngrain-growingregionhasapredominantlysummer-rainfallpattern

thatimposesconstraintsonexistingcroppingsystems,butalsoprovidesopportunities

cusin




December 2014



tomaximisetheuseofavailableresourcessuchasrainfall,sunlight,temperatureandsoil

nutrients.

1.9.2 ConstraintsConstraintsoccurwhenproductionresourcesareconcentratedintoafewmonthsofthe

year.Thepracticeofgrowingasinglecropperyearperfieldwasteslargeproportionsof

keyinputssuchasrainfallandsunlight.Forexample,rainfallthatoccursoutsidethecrop

growthperiodishighlysusceptibletolossesbydeepdrainage,run-offandevaporation.

Figure 15: Probability of finding the Parana (Argentine Pampas) climate in northern NSW and south-eastern Queensland cropping regions.




December 2014



1.9.3 OpportunityOpportunityariseswhenincreasingtheproportionoftheseresourcesthatisusedbycrops

andtransformedintoyield.

ScientistsfromtheUniversityofQueenslandandDAFFQld,withthesupportofthe

AustralianCentreforInternationalAgriculturalResearchandthecollaborationofSIMLESA

partners(http://aciar.gov.au/simlesa),arerunningtrialsatDAFF’sGattonResearchStation

thatarealreadyhelpingQueensland’sDarlingDownsgrowers.

AsincommercialfarmsfromtheArgentinePampas,growingmultiplecropsonthesame

areaoflandduringthesameseasoncouldhelpQueenslandgrowerstoreducewater

‘leaks’andincreaselandproductivityandgrossmargins.Figure15 isamapofQueenslandshowingtheareaswithasimilarclimatetotheArgentinePampas.

Initialresultsshowthatrelay-croppingmungbeansintoamaizecropbetweenmaturity

andharvestcanmorethandoublelandproductivity(2.4-foldincrease)andincreasegross

margins1.5-fold(Table8).However,mungbeanssownoutsidethisplantingwindow

producedlowgrainyieldsandreturnedanegativegrossmargin.

Table 8: Maize and mungbean yields from various cropping systems

Maizeandmungbeanyieldsaremoisturecorrectedto14%and12%,respectively.GrossmarginsarebasedonestimatesfromtheNSWDPIFarmBudgetSeriesSummer2011-12.Themaizecomponentofthedouble-cropsystemisassumedthesameassolemaize.NA,Notavailable

Cropping system Grain yield (t/ha) Gross margin ($/ha)

Maize Mungbean Maize Mungbean Total

Sole maize 9.38 – 1808 – 1808

Mid-vegetablerelay 9.44 0.02 1808 –399 1409

Mid-grainfillrelay 9.56 1.24 1840 579 2419

Physiologicalmaturityrelay NA 1.59 NA 858 2666

Double crop 9.38 0.37 1808 –119 1689

1.10 Nematode status of paddock

Inthenortherngrainregion,theroot-lesionnematode(RLN)Pratylenchus thorneiandthe

secondaryspecies,P. neglectus,arefoundinthree-quartersoffieldstested.

ResistanceandsusceptibilityofcropscandifferforeachRLNspecies.Maizeisconsidered

moderatelyresistanttobothspecies.41

1.10.1 Nematode testing of soilItisimportanttohavepaddocksdiagnosedforplantparasiticnematodessothatoptimal

managementstrategiescanbeimplemented.Testingyourfarmwilltellyou:

• ifnematodesarepresentinyourfieldsandatwhatdensity

• whichspeciesarepresent

41 KOwen,JSheedy,NSeymour.Rootlesionnematode—Queensland.SoilQualityPtyLtdFactSheet,http://www.soilquality.org.au/factsheets/root-lesion-nematode-in-queensland

i More information

GMMurray,JPBrennan

(2009)Thecurrentand

potential costsfrom

diseasesofwheatin

Australia.

KOwen,JSheedy,N

SeymourRootlesion

nematode—Queensland.

FactSheet.


http://aciar.gov.au/simlesa

http://www.soilquality.org.au/factsheets/root-lesion-nematode-in-queensland


https://www.grdc.com.au/~/media/B4063ED6F63C4A968B3D7601E9E3FA38.pdf











December 2014



Itisimportanttoknowwhichspeciesarepresentbecausesomecrop-management

optionsarespecies-specific.Ifaparticularspeciesispresentinhighnumbers,immediate

decisionsmustbemadetoavoidlossesinthenextcroptobegrown.Withlownumbers,

itisimportanttotakedecisionstosafeguardfuturecrops.Learningthatapaddockisfree

ofthesenematodesisvaluableinformationbecausestepsmaybetakentoavoidfuture

contaminationofthatfield.42

Testingofsoilsamplestakeneitherbeforeacropissownorwhilethecropisintheground

providesvaluableinformation.

1.10.2 Effects of cropping history on nematode statusRoot-lesionnematodenumbersbuildupsteadilyundersusceptiblecropsandcause

decreasingyieldsoverseveralyears.Theamountofdamagecausedwilldependon:

• thenumbersofnematodesinthesoilatsowing

• thetoleranceofthevarietyofthecropbeinggrown

• theenvironmentalconditions,includingrotations

Generally,apopulationdensityof2000RLN/kgsoilanywhereinthesoilprofilehasthe

potentialtoreducethegrainyieldofintolerantwheatvarieties.

AtolerantcropyieldswellwhenhighpopulationsofRLNarepresent(theoppositeis

intolerance).AresistantcropdoesnotallowRLNtoreproduceandincreaseinnumber(the

oppositeissusceptibility).

Growingresistantcropsisthemaintoolformanagingnematodes.Informationonthe

responsesofcropvarietiestoRLNisregularlyupdatedingrowerandDAFFplanting

guides.NotethatcropsandvarietieshavedifferentlevelsoftoleranceandresistancetoP.

thornei and P. neglectus.

For more information, download Managementofroot-lesionnematodesinthenorthern

grain region.

SummercropshaveanimportantroleinmanagementRLN.Researchshowsthatwhen

P. thorneiispresentinhighnumbers,twoormoreresistantcropsinsequenceareneeded

toreducepopulationstolowenoughlevelstoavoidyieldlossinthefollowingintolerant,

susceptiblewheatcrops.43

Formoreinformationonnematodemanagement,seeGrowNotesSection8:Nematodes.

42 QueenslandPrimaryIndustriesandFisheries(2009)Root-lesionnematodes—managementofroot-lesionnematodesinthenortherngrainregion.QueenslandGovernment,http://www.daff.qld.gov.au/__data/assets/pdf_file/0010/58870/Root-Lesion-Nematode-Brochure.pdf

43 KOwen,TClewett,JThompson(2013)Summercropdecisionsandrootlesionnematodes.GRDCUpdatePapers16July2013,http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/07/Summer-crop-decisions-and-root-lesion-nematodes

i More information

http://www.

crownanalytical.com.au

PreDicta B. SARDI

DiagnosticServices.

QPIF(2009)Root-

lesionnematodes—

management of root-

lesionnematodesinthe

northerngrainregion.

i More information

K Owen, T Clewett,

JThompson(2013)

Summercropdecisions

androotlesion

nematodes.GRDC

UpdatePapers.


http://www.daff.qld.gov.au/__data/assets/pdf_file/0010/58870/Root-Lesion-Nematode-Brochure.pdf




http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/07/Summer-crop-decisions-and-root-lesion-nematodes


http://www.crownanalytical.com.au


http://www.sardi.sa.gov.au/products__and__services/entomology/diagnostic_services/predicta_b







https://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/07/Summer-crop-decisions-and-root-lesion-nematodes








December 2014



1.11 Insect status of paddock

Emergingmaizecropsarepronetoattacksfromsoilinsects,andifleftunchecked,acostly

replantmaybetheonlyoption,withnoguaranteethesamewillnothappenagain.Seedling

mortalityof30–40%willhaveamarkedeffectonyieldduetothelowerplantpopulation.

Soilinsectsaremoreprevalentinearlyspring,coincidingwithrisingsoiltemperaturesand

pupaeandlarvaemovingfromdeeperinthesoil.

Changingfarmingpractices,suchasreducedtillage,no-tillageandpermanentbeds,may

actuallyfavourthebuild-upofsomesoilinsects.Traditionalformsofcultivationplusdeep

rippingseemtohaveanadverseeffectonpupaeandlarvaeandhenceonsoilinsect

populations.

Themainsoilinsectstobecontrolledarewireworms,falsewireworms,blackfieldearwigs

andAfricanblackbeetle.

StillpopularinQueensland,whereitisregistered,istheuseofbeetlebait,whichisapplied

tothesurfaceofthesoilforthecontrolofabovegroundinsectssuchasAfricanblack

beetles,falsewireworms,fieldcrickets,winglesscockroachesandblackfieldearwigs.

Fromtimetotimegrasshoppers,fieldcricketsandwinglesscockroachescanbuildupin

numberstobecomeaproblem.Controlwithasurfacesprayofaregisteredinsecticidemay

be warranted. 44

1.11.1 Soil sampling for insectsCroprotationisalsoakeystrategyinmanagingpestssuchasAfricanblackbeetlein

maize,includingavoidingfollowingrecentlycultivatedpasture.Inclaysoils,samplingthe

seedbedpriortoplantingisdifficult,butwarrantediftheriskishigh.Toestimatethesoil

population,digandsievesoilfrom10randomlylocatedquadrats(20cmby20cmby30

cmdepth).Theonlyinsecticidetreatmentavailableisanin-furrowapplicationofchlorpyrifos

duringplanting.However,thistreatmentisnoteffectivewhenbeetlenumbersarehigh(≥10

individuals/m.)orwhenswarmsofbeetlesflyintothecropafterplanting.45

Itisparticularlyimportanttomonitorandcontrolsoil-dwellinginsectssuchaswirewormsat

sowing.46

Soil-dwellinginsectpestscanseriouslyreduceplantestablishmentandpopulations,and

subsequentyieldpotential.


45 NMoore,LSerafin,LJenkins(2014)Summercropproductionguide2014.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/agriculture/broadacre/guides/summer-crop-production-guide

46 DPI(2005)Grainsorghum.AgfactP3.3.5.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0006/146355/grain-sorghum.pdf





http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0006/146355/grain-sorghum.pdf




December 2014



Soilinsectsinclude:

• cockroaches

• crickets

• earwigs

• blackscarabbeetles

• cutworms

• falsewireworm

• true wireworm

Differentsoilinsectsoccurunderdifferentcultivationsystems,andfarmmanagementcan

directlyinfluencethetypeandnumberofthesepests:

• Weedyfallowsandvolunteercropsencouragesoilinsectbuild-up.

• Insectnumbersdeclinefromlackoffoodduringacleanlongfallow,butflareatsowing

timewhenraingerminatesweeds,attractingthesesoilinsects.

• Summercerealsfollowedbyvolunteerwintercropspromotethebuild-upofearwigs

andcrickets.

• Highlevelsofstubbleonthesoilsurfacecanpromotesomesoilinsectsbecauseofa

foodsource;however,thiscanalsomeanthatpestscontinuefeedingonthestubble

insteadofongerminatingcrops.

• No-tillageencouragesbeneficialpredatoryinsectsandearthworms.

• Incorporatingstubblepromotesblackfieldearwigpopulations.

• Falsewirewormsarefoundunderallintensitiesofcultivationbutnumbersdeclineif

stubblelevelsareverylow.

Soil-insectcontrolmeasuresarenormallyappliedatsowing.Becausedifferentinsects

requiredifferentcontrolmeasures,thespeciesofsoilinsectsmustbeidentifiedbefore

planting.

Soil sampling by spade

1. Takeanumberofspadesamplesfromrandomlocationsacrossthefield.

2. Checkthatallspadesamplesaredeepenoughtoincludethemoistsoillayer(thisis

essential).

3. Hand-sortsamplestodeterminetypeandnumberofsoilinsects.

4. Spadesamplingislaborious,time-consuminganddifficultinheavyclayorwetsoils.

Germinating-seed bait technique

Immediatelyfollowingplantingrain:

1. Soakinsecticide-freecropseedinwaterforatleast2htoinitiategermination.

2. Buryadessertspoonoftheseedunder1cmofsoilateachcornerofa5mby5m

squareatfivewidelyspacedsitesper100ha.

3. Markthepositionoftheseedbaits,aslargepopulationsofsoilinsectscandestroy

thebaits.

4. Onedayafterseedlingemergence,diguptheplantsandcounttheinsects.


http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/a-z-insect-pest-list/soil-insects/wingless-cockroach

http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/a-z-insect-pest-list/soil-insects/black-field-cricket

http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/a-z-insect-pest-list/soil-insects/black-field-earwig

http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/a-z-insect-pest-list/black-sunflower-scarab

http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/a-z-insect-pest-list/soil-insects/cutworm

http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/a-z-insect-pest-list/soil-insects/false-wireworm

http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/a-z-insect-pest-list/soil-insects/true-wireworm



December 2014



Trialshaveshownnodifferenceinthetypeofseedusedforattractingsoil-dwellinginsects.

However,useofthetypeofseedtobesownasacropislikelytoindicatethespeciesof

peststhatcoulddamagethatcrop.

Themajordisadvantageofthegerminating-grainbaitmethodisthedelaybetweentheseed

placementandassessment.

Detecting soil-dwelling insects

Soilinsectsareoftendifficulttodetectbecausetheyhideundertrashorinthesoil.

Immatureinsectssuchasfalsewirewormlarvaeareusuallyfoundatthemoist–drysoil

interface.

ForcurrentchemicalcontroloptionsseethewebsitesofPestGenieAustralia or APVMA. 47

47 DAFF(2011)Howtorecogniseandmonitorsoilinsects.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/help-pages/recognising-and-monitoring-soil-insects

i More information

DAFF(2011)How to

recogniseandmonitor

soilinsects.

PestGenie.

APVMA.


http://www.pestgenie.com.au/

http://www.apvma.gov.au/

http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/help-pages/recognising-and-monitoring-soil-insects



http://www.pestgenie.com.au/


Section 2 MAIZE - Pre-planting


December 2014



SECTION2

Pre-planting

2.1 Selecting maize varieties

Manymaizevarietiesareavailable.Thechoiceofvarietywilldependonmarket

requirements,environmentalconditions,whetherthecropisirrigated,andthelevelof

diseaseresistancerequired.Varietiesarecontinuallychanging,soensurethatyouhaveup-

to-date varietal information.

Oncethedecisionhasbeenmadetoincludemaizeinasummercroppingprogram,

thoughtthenmustbegiventowhichmarketyouareaimingatandthegroupofvarietiesor

thevarietythatbestsuitsyoursituation(Table1). 1

Table 1: Key to maize ratings

CRM,Cumulativerelativematurity

End use Husk cover Disease reaction Stalk strength (lodging resistance)

CRM (days)

S,starch

P,processing

F, feed

Sil,silage

TO,tightopen

TC,tightclosed

MO, medium open

MC,mediumclosed

LO,looseopen

LC,looseclosed

S,susceptible

MS,moderatelysusceptible

MR,moderatelyresistant

R,resistant

NA, not available

*verypoor

** below average

*** intermediate

**** above average

*****verygood

100–112quick

113–115mediumquick

116–120medium

121–130mediumslow

131+slow


i More information

ECorsan(2010)

Developmentsinmaize

technologyfroma world

perspective.

Releaseofanew

generation of maize

inbredlines2013.The

Cob, autumn 2014, p. 4.




https://www.grdc.com.au/uploads/documents/2010ASGCPowerPointPresentationsPDF/Corsan_MaizeTechnology_slides.pdf




http://www.maizeaustralia.com.au/cob_files/autumn2014.pdf






December 2014



2.2 Maize variety characteristicsTable 2: Maize hybrid characteristics

Hybrid CRMΔ

NSW area of adaptation End use

Husk cover∞

Disease reactions◊ Lodging^Company recommendations

Target plant population/ha × 1000Seed brand

Turcicum leaf blight Rust

Cob rot Root Stalk Irrigation

Dryland > 650mm

Dryland < 650mm

MFY136 82

Quick

All Feed,Silage M 8 7 9 9 9 75–100 40–75 35–45 HSR

MFY139 88 All Feed,Silage M 7 7 9 8 9 75–100 40–75 35–45 HSR

P9400 94 SouthernInland

Feed,Silage M 7 6 6 8 8 80–100 – – Pioneer

P0021 100 SouthernInland

Feed;Silage M 7 6 tbc 7 7 75–95 – – Pioneer

PAC 301 102 Central/SouthernNSW

Grain VT 7 9 7 7 7 90–110 60–80 20–40 PacificSeeds

Maximus 102 All Feed;Silage M 8 9 7 9 9 75–100 40–75 35–45 HSR

P1070 110

Medium–quick

All Feed,silage M 6 5 7 8 9 70–90 45–65 20–35 Pioneer

Olympiad 112 All Feed;Silage M 8 8 8 9 9 75–100 40–75 35–45 HSR

NeroIT 112 All Feed;Silage M 7 8 7 9 9 75–100 40–75 35–45 HSR

P1467 114 All Feed;Silage M 5 5 7 8 9 70–90 45–65 20–35 Pioneer

32P55 114 All Feed;Grits;Silage

MT 7 7 7 8 9 60–75 30–45 20–35 Pioneer

PAC 606 114 All Feed;Silage MT 9 7 7 7 8 80–100 40–60 20–40 PacificSeeds

HM-114 114 All Feed;Silage T 5 7 – 8 9 60–75 30–45 20–30 Heritage Seeds

PAC 624 117 All Feed;Silage MT 7 7 7 8 7 65–75 35–45 20–35 PacificSeeds

P1756 117 All Feed;Silage, Grit

M 6 7 7 8 9 60–75 30–45 20–35 Pioneer

PAC 607IT° 118

Med

ium

All Feed;Silage MT 7 7 7 8 7 65–75 35–45 20–35 PacificSeeds

PAC 735 118 All Grit;Silage MT 7 8 7 9 9 55–75 35–50 20–35 PacificSeeds

Sirus 118 All Feed;Silage M 8 8 7 9 9 75–100 40–75 25–35 HSR

P1813IT 118 All Feed;Grit;Chips

T 7 6 7 8 9 60–75 30–45 20–35 Pioneer

Amadeus 118 All Feed;Grit;Chips

M 9 9 8 8 8 75–100 40–75 35–45 HSR

AmadeusIT

118 All Feed;Grit;Chips

M 9 9 8 8 8 75–100 40–75 35–45 HSR

HM-135 118 All Feed;Silage MT 5 7 – – – 60–75 30–45 20–30 Heritage Seeds

PAC 345IT° 119 Inland Feed;Grit;Chips

MT 5 7 8 8 6 60–70 35–45 25–35 PacificSeeds

PAC 727 123

Medium–slow

NorthernInland;NorthCoast

Feed;Grits;Silage

MT 6 7 7 8 7 55–70 35–50 20–30 PacificSeeds

P2307 123 NorthCoast,

South-Central Inland

Silage;Grit VT 9 – 7 – 7 50–65 30–45 20–25 Pioneer

HM-102 123 NorthernInland;NorthCoast

Feed;Silage T 5 8 8 7 7 50–65 30–45 20–30 Heritage Seeds

Specialty Hybrids

Thunderpop 112 ButterflyPopcorn

MT 7 7 8 7 7 75–100 40–90 30–50 DolphinSeeds

Blaster 114 MushroomPopcorn

MT 7 7 8 7 7 60–75 40–50 25–30 DolphinSeeds




December 2014



°IT=imidazolinetolerant;#IR=imidazolinoneresistant; ∞HuskCover;M=moderate;MT=moderate/tight;T=Tight;VT=VeryTight; ^LodgingResistance;1=Poor;5=Average;9=Excellent; ◊DiseaseReactions;1=HighlySusceptible;5=Intermediate;9=HighlyResistant;NR=NotRecommended; –=NoInformation; ΔCRM=CornRelativeMaturity

2.2.1 MaturityInthemaizebeltoftheUSA,maturityisveryimportantbecauseoftherelativelyshort

growingseason;adelayinplantingof3or4daysmaymeanchangingtoadifferenthybrid

thathasaslightlyshortercumulativerelativematurity(CRM).

Duetovideosettings,thismaynotbeviewableonmobiledevices.

InAustralia,thelatitudeofnorthernregionproductioncreatesawideplantingwindowand

maturityisnotascritical.

Longerseasonvarieties(111–130daysCRM)grownfromtheLiverpoolPlainsnorthhave

ahigheryieldpotentialthanthequickermaturingvarieties,butfurthersouth,thequicker

varieties(108–111daysCRM)havesimilaryieldpotential.Yieldsfortherange100–111

daysCRMhaveseenthelargestimprovementsinthelast10years.

Quickermaturityvarietiesthanusualforaregionmaybeplantedincasesof:

• watercutbacksorwantingtofinishthecropbeforethepeakwaterrequirementsfor

othercropsinthehotJanuary–Februaryperiod

• delayedspringplantingwiththeaimofbeatingthesummerheatbeforetasselling

• alateplantandathreatofanearlyfrostinterfering2

2.2.2 Time to floweringUnderconditionsofadequatesoilmoisture,mid-toslow-maturinghybridswillproducea

higheryieldthanquick-maturinghybrids.Therefore,growersaimingformaximumyields

shouldconsideramid-tofull-seasonmaturityhybrid.However,whereirrigationislimited,


i More information

NMooreetal.(2014)

Summer crop production

guide 2014. NSW

DepartmentofPrimary

Industries.

Corn.PacificSeeds.

Corn. Du Pont Pioneer.

Maizeseed.HSRSeeds.

Summer crop planting

guide.Northernedition.

HSRSeeds.


http://youtu.be/e37mGARGZTQ



http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0005/303485/Summer-crop-production-guide-2014.pdf





http://www.pacificseeds.com.au/products/corn.html

http://www.pioneer.com/web/site/australia/products/corn/

http://www.hsrseeds.com.au/maize-seed/

http://hsrseeds.com.au/wp-content/uploads/2014/08/HSRNORTHERN_SummerCropBrochure2012_lowres.pdf





December 2014



amid-seasonhybridmayproducegreateryieldpermegalitreofwater.Thismayalsobe

thecaseinfullyirrigatedsituationswhereitisdesiredtolimitthenumberofirrigations

foreconomicreasonsortoplantafollowingcroptoobtainmaximumuseofseasonal

conditions.Indrylandenvironments,commercialfull-seasonhybridscanhandleheatand

moisturestressandthenrespondtoabreakintheweather.

Growers,particularlyindrylandsituations,maywishtoreducetheriskofyieldlosscaused

byunfavourableseasonalconditionsbyplantinganumberofhybrids,perhapswitharange

ofmaturities.3

2.2.3 AdaptabilityAvarietydoesnotperformequallyunderallconditions.Thebestvarietiesshouldyieldand

standwellinbothfavourableandlessfavourableconditions.Choosevarietiesthatperform

consistentlyunderthechosengrowingconditions. 4

2.2.4 Cob heightCobheighttendstobecorrelatedwithmaturity.Longerseasonhybridsusuallyhave

highersetcobsthanquickermaturinghybrids.Excessivecobheight,>1.5m,canbea

contributingfactortorootlodging(especiallyifthereiswindandrainaroundflowering)and

tostalklodging(particularlyifstalkrothasinfectedtheplants).Lodgedplantscanbeslow

toharvestandcanreduceyield. 5

Somehybrids,particularlythree-waycrosses,inverygoodconditionscanproducemultiple

cobs,buttheyareusuallyexpressedatlowerplantpopulations.Year-in,year-out,avariety

withonegoodcobthatflexesitslengthratherthanthenumberofcobsismoredesirable.

Varietieswithalongershank,allowingcobstohangdownapproachingmaturity,haveless

cobdamagethanvarietieswithuprightcobsatmaturity. 6

2.2.5 Husk coverHusksfunctiontopreventdamagefromHelicoverpa spp.larvae,reduceearorkernel

rots(causedbyDiplodia, Fusarium)andsmuts,andprotectthegrainfromweathering.

Therefore,agoodhuskcover(includingtipcover)canbeimportantifinsects,disease,

andpre-harvestrainarelikelytoposethreats.However,inareaswherequickdry-downis

necessarybecauseofashortseason,hybridswithlight,loosehusksmaybebestsuited. 7

Huskcoverisanimportantconsiderationforcoastalenvironmentswhereprotectionfrom

theweatheriscrucial.Openhuskvarietiesgrownincoastalareastendtohavemorecob

3 DAFF(2012)Varietiesandplantingofmaize.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/varieties-planting






http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/varieties-planting








December 2014



rotsthantighterhuskvarieties.Tighterhuskcoveronprocessinghybridsisalsomore

desirable,reducinginfieldstressfracturing.

Ontheotherhand,aloosehuskcoverisoftenconsideredanadvantageforinland

growersbecauseitencouragesrapiddry-down. Recentfindingsindicateahigherlevelof

mycotoxins inloosehuskcovervarietiesthantighterhuskcovervarieties.8

2.2.6 StandabilityStandability(resistancetolodging)isimportantbecauseitreducesharvestlossesandgrain

damage.Manyfactorscontributetostandability,includingresistancetostalkrots,good

mechanicalstalkstrength,sowingrateandcobheight.Mostmodernhybridshavegood

standability,butsomeseasonalconditions(e.g.waterstressduringgrainfill)cancause

seriouslodging.Alwayschoosehybridswithgoodtoexcellentstandabilityanddiscuss

optimalsowingpopulationwithyouragronomist. 9

2.2.7 End useHybridsgenerallyhavespecificgraincharacteristics,whichgoverntheirsuitabilityfor

particularendusessuchasmillingforgrits,stockfeed,silageorotherspecial-purpose

uses. 10

2.2.8 IsolationAllwhite,waxyandpopcornvarietiesofmaizemustbegrowninisolation(bothindistance

andtime)fromothermaizevarieties,aspollenfromothercropswillaffectthequalityof

grainproducedbythesetypes.Seedcompaniesorgrainpurchasersmayhavespecific

recommendationstofollow.11

2.2.9 TillersSuckers(ortillering)areconsideredundesirableanduntidy.Plantbreederstrytoeliminate

thistraitintheirbreedingprogramseventhoughitisveryseasonal.

Somevarietiesaremorepronetotilleringthanothers.Tilleringisusuallytriggeredby

highlevelsofnutrition,especiallynitrogenavailabilitytotheplantearlyinitslife,adequate

moistureavailability,coolertemperaturesearlyinthecrop’sgrowthandlowerplant

populations.

Sometimesthesetillersmayhavehermaphroditeearsontopofthetiller,butusuallyby

harvesttime,birdshaveraidedthegrainthathasset.Researchhasshownnoyieldpenalty

withtillers.However,farmersoftenbelievethattheplantusesmoistureandnutrientsto













December 2014



growtillersand,insomecases,alittlegrainontop.Laterintheseason,themainplant

drawsthenutrientsbackasthetillerstendtodieoff.12

2.2.10 The final decision—which variety?Aswithmanyofcrops,itisadvisabletospreadyourmaizeproductionrisksbyplantinga

numberofvarietiesoratruedual-purposevarietytoprovideoptionsofsellingyourcrop

intomanydifferentmarkets.

Again,itisimportanttounderstandthatthebestyieldingvarietyfromlastseasonisnot

necessarilythebestselection.Considerationneedstobegiventovarietiesthathave

performedoveranumberofyearsingoodandbadseasons.Lookfortrialdatainyourlocal

area,ifnotfromyourownproperty,orconsultyouragronomist. 13

2.3 Planting seed quality

Growersexpecthigh-quality,geneticallypureseed.Asaresult,seedcompaniesmaintain

qualitycontrolprogramsthatmonitorseedfromharvesttopurchase.‘Traditional’seed-

qualitytests,includingmechanicaltestsandtestsofgeneticpurity,seedgerminationand

vigour,andseedhealthtestsareused,andseedqualityassessmenttechniquescontinue

toevolve.Advancesinmoleculargeneticsareallowingthereleaseofnewvarietiesdiffering

essentiallyinonegene.Newmolecularbiologyapproachesofferthepotentialtoidentify

thesesubtlegeneticdifferences.

Advancesinseedenhancements,suchaspelleting,primingandpre-germination,require

increasedscrutinyofseedqualitybeforeandaftertheenhancementprocess.New

developmentsincomputerimagingforimprovedpurityandgermination–vigouranalysesare

beingdeveloped.Thesenovelapproachestoseed-qualityassessmentbecomeimportant

asnewgeneticimprovementsareconveyedintheseedatincreasedcosttothegrower.14

2.3.1 Seed sizeSeedhassizeandshapegradings.Maizeseedvariesfrom4400seed/kg(small)to2500

seed/kg(large).Refertobagforanexactseedcount.15Seedshapeconsistsofrounds

orflats.Flatseedisgenerallybestinplateseeders,whileroundseedispreferredbyair

seeders.Thereisnodifferencebetweenthecropsproducedbytheseseedshapes.

Informationonthegerminationpercentageandthedatethetestwasconductedshould

alsobewiththebag.16



14 MBMcDonald(1998)Seedqualityassessment.SeedScienceResearch8,265–276,http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1356024&fileId=S0960258500004165



i More information

CJBirch et al. (2006)

Analysisofhighyielding

maizeproduction—a

studybasedona

commercialcrop.In6th

Triennial Conference,

MaizeAssociationof

Australia.

i More information

JMPetersonet al.

(1995)Influenceofkernel

position,mechanical

damage and controlled

deterioration on

estimatesofhybrid

maizeseedquality.Seed

Science andTechnology

Vol.23.

EYHosanget al.(2012)

Analternativestorage

techniqueformaintaining

seedqualityinEast

Timor.In16thAustralian

AgronomyConference.

i More information

AMSmith(1970)Effect

offungicidesonthe

germination of maize

seedafterstorage.

AustralianJournalof

ExperimentalAgriculture

Vol.10.






http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1356024&fileId=S0960258500004165




http://www.maizeaustralia.com.au/events_files/Analysis of high yielding maize production - CJ Birch, A Sawers.pdf








http://cat.inist.fr/?aModele=afficheN&cpsidt=3003381









http://www.regional.org.au/au/asa/2012/crop-production/7992_hosangey.htm






http://www.publish.csiro.au/paper/EA9700174.htm









December 2014



2.3.2 Safe rates of fertiliser sown with the seedMaizedoesnottoleratehighlevelsoffertiliserincontactwiththeseed,socareshouldbe

takentoavoidthisatplanting.Astarterfertiliser(smallpercentageofnutrientrequirement)

maybeplacedwiththeseediflowsoiltemperaturesorcool,waterloggedsoilsarelikely

afterplanting.Thisprovidestheseedwithareadynutrientsource.Thestartingfertiliser

shouldnotexceed5kgnitrogenand10kgphosphorus/hawhensownin90-cmrows.The

applicationofacompoundfertiliser(NPK)drilled5cmtothesideoforbelowtheseedis

preferable(Figure1).17

Figure 1:

5 cm (2 in)Seed

Fertiliser band

5 cm(2 in)

Application of a compound fertiliser (NPK) drilled 5 cm to the side of the seed is preferable.

Potassiumshouldnotbeplacedintheseedtrenchatsowing,becauseonlyminoramounts

areallowablewithseedandthesearenotcost-effective.Below5cm,however,growers

canplaceasmuchasrequired,similartonitrogen.

17 DAFF(2012)Nutrition,irrigationandweedsformaize.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/nutrition-irrigtion

i More information

Carewithfertiliserand

seedplacement.Fertiliser

toxicity.GRDCFactsheet

May2012.

Urea.FertiliserFacts.

Incitec Pivot Ltd.

Nutrition, irrigation

andweedsformaize.

Department of


ForestryQueensland.


http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/nutrition-irrigtion


http://www.grdc.com.au/GRDC-FS-FertiliserToxicity




http://farmercommunity.incitecpivotfertilisers.com.au/Articles and Publications/Fertiliser Facts/Urea

http://farmercommunity.incitecpivotfertilisers.com.au/Articles and Publications/Fertiliser Facts/Urea






Section 3 MAIZE - Planting


December 2014



SECTION3

Planting

3.1 Seed treatments

Useofaseedtreatmentatplantingisrecommendedformaizebecauseearly-plantedcrops

usuallyencounterthemostpressurefrominsectsanddiseases;falsewireworminparticular

aregenerallyinabundanceintheearlypartoftheseason.1

Researchershaveexaminedtheeffectofseedtreatmentswiththreefungicides,Ceresan

(2.3%phenylmercuryacetateand0.4%ethoxymercurysilicate),Coversan(96%

tetrachloro-p-benzoquinone)andPanogen(2.2%methylmercurydicyandiamide),onthe

germinationoftwocultivarsofmaizestoredforupto12monthsaftertreatment.None

ofthetreatmentsaffectedthegerminationofmaize. 2Thistreatmentisnotcurrently

registered.

3.2 Soil type

Maizewillgrowonawiderangeofsoiltypes,providingthesoilsarewelldrained.ApH

rangeof5–8canbetoleratedbutbestgrowthisachievedintherangeofpH5.6–7.5.

Maizedoesnotgrowwellinsalinesoils.Yieldreductionsof≥10–20%canbeexperienced

ifsoilextractshaveanelectricalconductivity(EC)of2.0–4.0dS/m.Yielddeclineislikelyif

irrigationwaterhasanECof>1.5dS/m.Seedlingandflowergrowthismostsensitiveto

salinity.3

1 Earlypestofsorghumandmaize.AgronomyTopics.PacificSeeds,http://www.pacificseeds.com.au/info-and-tools/agronomy-topics/78-early-pest-of-sorghum-and-maize.html

2 AMSmith(1970)Effectoffungicidesonthegerminationofmaizeseedafterstorage. Australian Journal of Experimental Agriculture and Animal Husbandry10,174–175,http://www.publish.csiro.au/paper/EA9700174.htm


Research trial results

Researchershaveexaminedtheeffectofseedtreatmentswiththreefungicides,Ceresan

(2.3%phenylmercuryacetateand0.4%ethoxymercurysilicate),Coversan(96%

tetrachloro-p-benzoquinone)andPanogen(2.2%methylmercurydicyandiamide),onthe

germinationoftwocultivarsofmaizestoredforupto12monthsaftertreatment.None

ofthetreatmentsaffectedthegerminationofmaize. 2Thistreatmentisnotcurrentlyregistered.i More

informationAMSmith(1970)Effect

offungicidesonthe

germination of maize

seedafterstorage.



Authority.


http://www.pacificseeds.com.au/info-and-tools/agronomy-topics/78-early-pest-of-sorghum-and-maize.html















December 2014



3.3 Time of sowing

Thedecisionaboutwhentoplantshouldbebasedonsuitablesoiltemperaturein

combinationwiththelastexpectedfrost,afullprofileofmoistureparticularlyfordryland

production,avoidingfloweringduringexpectedpeaktemperatureperiods,andtherefore

workingbacktoasuitableplantingdate.Consequently,foralateplant,trytotimeflowering

afterthemainsummerheatbutearlyenoughtobeatthefirstexpectedfrost.Laterplanted

cropsaresubjecttohigherinsectanddiseasepressure.

Early-plantedmaizeshadesthesoilearlierintheseason,thusreducingwaterlostto

evaporation;italsoreachesthemostcriticalstageofsilkingwithmorewaterleftinthe

subsoil,alongwithadeeperrootsystemcapableofextractingmoreavailablewater.4

Earliersowingperiodsprovideadvantages;theseincludehavingmorestoredwater

availabletofollowingcrops,eitherdouble-croppedorthefollowingsummercrop.

Sowingtimeisgovernedby:

• soiltemperature

• soilmoisture

• targetedfloweringdateandcultivar

3.3.1 Soil temperatureAlthoughmaizewillgerminatewhenthesoiltemperaturereaches10°C,itisadvisablenot

toplantuntilthegroundtemperaturereaches12–14°Cat09:00(9am)atadepthof10cm

foratleast3or4consecutivedays.Evenat12°C,maizewilltakeupto2weekstoemerge,

andthelongerittakesthemorepronetheseedlingistoinsectattacksanddamping-off

diseases.

4 PacificSeeds(2008/2009)Hybridcornagronomyguide2008/09.PacificSeedsPtyLtd,http://cairo.directrouter.com/~pacseeds/images/stories/corn/information/cornagronomy08.pdf

i More information

N Moore et al.(2014)


guide. NSW DPI

Management Guide.


https://www.pioneer.com/home/site/mobile/plant/corn/soil-characteristics-planting/









December 2014



Theyoungmaizeplantwilltoleratelightfrostsaslongasthegrowingpointisstillbelow

thesoilsurface,whichisaboutthe6–8-leafstage.Leaveswillstillbeburntoffbutwillbe

quicklyreplacedwithnewones.Ifafrostaffectsthegrowingpoint,itwillnormallytillerand

will require a replant.

Anearlyfrostonlate-plantedmaizecanhaveamajoreffectifitissevereandthecropisnot

atphysiologicalmaturity(blacklayer).

Hybridsofdifferentmaturitiesarerecommendedfordifferentlatitudes(Table1).InAustralia,

exceptforthesouthernareas,thereisawideplantingwindowandmaturityisnotascritical

asitisintheUSA.

Table 1: A guide to the general maturity plantings in Australia

CRM,Comparativerelativematurity

Location CRMTasmania,GippslandandWesternDistricts Under100CRM

NEVic.,SAandsoutherntipofWA 97–113CRM(canbeslightlylongerforsilage)

MIA,LachlanandMacquarieValleys 105–118CRM(longerendofrangeforgrits&silage)

LiverpoolPlainsandnorthernNSW 108–118CRM

Sydneybasin,mid/northcoast,NorthernRiversofNSW

115–126CRM

DarlingDownsandBurnett 108–120CRM

CentralQueenslandandCallideDawson 111–118CRM

NorthQueensland 118–130CRM

Maizedoesnotgerminateatsoiltemperatures<10°C.Commencesowingwhenthe9am

ESTsoiltemperatureatsowingdepthreaches12°Candisrising.Forirrigatedcrops,the

temperatureofwaterusedforpre-irrigationorwatering-upcaninfluencesowingtime.If

watering-up,allowforadecreaseof3–4°Cinsoiltemperaturefollowingwatering.Therate

ofseedlingemergenceincreaseswithincreasingsoiltemperature.At12°C,emergencewill

occurin14days,whereasat25°Cemergenceoccursin4–5days.

Sowingtimeandhybridselectiondeterminewhetherthecropwillbeexposedtothehot

conditionsduringpollination,whichcansignificantlyreduceyield.Tassellingandsilking

occurs~8–10weeksafterplantingformid-maturityhybrids.Temperatures>35°Catthis

timeleadtopollenblasting,resultinginpoorkernelsetandyieldloss.Moisturestress

isalsomorelikelytooccuronhotdays.Intheinlandareas,temperatures>35°Care

mostlikelytooccurbetweenmid-Decemberandmid-February.Staggeredsowingtimes

mitigatestheriskoflargeyieldpenaltiesduetopollenblast.

Earlysowingbalancestherisksoffrostsoonafteremergenceandexcessiveheatat

flowering.Coldconditionsafteremergencewillslowseedlinggrowthandfoliagemayturn

purple,asphosphorus(P)islessavailableatlowsoiltemperatures;however,cropsrecover

asconditionswarmup.Youngcropscangenerallysurviveoneormorefrostsbecausethe

growingpointdoesnotappearabovethesoilsurfacefor3–4weeksafteremergence.

Latesowingavoidsexcessiveheatatfloweringbutincreasestherisksofinsectattackby

Helicoverpaandmites,diseaseinlatesummer,andslowdry-downperiodsincool,wet

autumns.Forthesereasons,quick-maturinghybridsarefavouredforlatesowings.




December 2014



Thenorthandcentralcoastregionhasthelongestgrowingseasonformaizein

Queensland.However,earlysowingopportunitiestendtobelimitedtoirrigatedsituations

becausespringiscommonlydry.Mainsowingisusuallydelayeduntilmid-November

throughDecember.Coastalrain-growncropsshouldbeplantedsothatthecriticalperiod

from2weeksbeforeto4weeksaftersilkingoccurswhenthereisahighprobabilityofgood

rain. 5 6

3.3.2 Planting moisture requirementDrylandmaizeshouldbeplantedonafullsoilmoistureprofile.Irrigatedcropsshouldbe

irrigatedpre-plantandthen,ifusingfloodirrigation,notwatereduntil6weeksold(pre-

tasselling).Ifconditionsarehotanddry,aquickflush2–3weeksafteremergencemaybe

required.

Maizeisnottolerantofwaterloggingespeciallyduringseedlingandfloweringstages.7

3.3.3 New South WalesOnthesouthcoastandthetablelandsofNewSouthWales(NSW),thesafetimetosowis

OctoberandNovember.Thisisduetotheriskoflatefrostsatthebeginningoftheseason

and/orearlyfroststowardstheendoftheseason.SeeTable2forfurtherdetail. 8

Table 2: Suggested sowing times for maize in NSW production areas

>,Earlierthanideal; ,optimumsowingtime;<,laterthanideal.NotethattheLiverpoolPlainsofNSWispronetofrostatbothearlyandlatesowingstagesthanBoggabriandothernorthernNSWareas

Region

Early plant Late plant

Aug Sept Oct Nov Dec Jan Feb

1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2

NorthernInland

> > < < > > < <

Central Inland

> > < <

SouthernInland

> > < <

Tablelands > > < <

NorthandCentral Coast

> > < <

SouthCoast

> < <





i More information

ARingrose-Voaseet al.

(2003)Deepdrainage

under different land uses

intheLiverpoolPlains

catchment.Agricultural

ResourceManagement

Series,NSW Agriculture.

NorthernNSW&

LiverpoolPlainsSummer

2012–13.DuPont

Pioneer.

JFScottet al.(2004)

Farmingsystemsinthe

northerncroppingregion

ofNSW:Aneconomic

analysisregionofNSW:

Aneconomicanalysis.

NSWDPIEconomic

ResearchReport.








http://www.clw.csiro.au/publications/consultancy/2003/Deep_Drainage_in_Liverpool_Plains.pdf







http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Northern_NSW_Liverpool_plains_regional_insert 2012 10.pdf




http://www.dpi.nsw.gov.au/research/economics-research/reports/err20










December 2014



3.3.4 QueenslandInsouthernQueensland,mid-Septembertomid-Octoberisthepremiumtimetosow.

Decemberprovidesanothersuitableopportunity,especiallyfordrylandcrops(Table3).

InMoreton,maizeisoftensuccessfullyplantedasearlyasmid-August.Latestplantings

intheseareaswouldoccurinearlytomid-January,becauseoflikelihoodofdisease

developmentinlatesummer–autumn.

Aminimumsoiltemperatureof12°Cisneededatseeddepthbeforeattemptingsowingin

mid-September.Coldconditionsafterestablishmentwillslowthegrowthofseedlingmaize,

oftencausingfoliagetoturnpurple,probablyduetoreducedPavailabilityatlowersoil

temperatures.However,oncetemperaturesbegintoriseagain,thecropcontinuestogrow

normally.Plantingatthistimewillavoidfloweringinmidsummerheat.

Decemberplantingsfloweraftermidsummerheatbutmaybemoresusceptibletodiseases suchasrust,leafblightsandwallabyear,andperhapsFusariumkernelrots.

Hot,dryweathercankillpollenasitisshedfromthetassel,orinduceunevenflowering.For

example,silkemergencefromthecobmaybedelayedandoccurwhenpollenisnolonger

beingshedfromthetassel,resultinginpoorseedsetonthetipoftheear.

InCentralQueensland,somewaxyandgritmaizeisplantedinmid-Augusttoearly

September,especiallyunderirrigation.However,themaincropisplantedlateJanuaryto

firstweekinMarch,toavoidheatstress,whichcanreducepollenviabilityatfloweringtime.

InFarNorthQueensland,irrigatedmaizeisplantedinlateJulytoAugust.Laterplantings

occurinlateNovembertolateJanuary,withtheoptimumtimebeingmid-December.

SuccessfulplantingshavebeenmadeinlateFebruary,butthesearetheexception,andthis

timeisnotrecommended. 9

Table 3: Suggested sowing times for maize in Queensland production areas

Optimalplantingtime;preferredplantingtime;d,higherdiseaserisk;r,suitablefordrylandcrops;i,satisfactoryunderirrigation;*,lateplantingnotrecommended;h,highriskofheatstressduringflowering

Region Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar.NorthQld *

Central Qld i i

SouthBurnett h h d d d d d

DarlingDowns r r r

Moreton d d d

3.4 Targeted plant population

Mostirrigatedcropsareplantedinrowsrangingfrom76to100cm,withthemajorityof

planterssetupfor100-cmrowspacing.Underirrigationandhigheryieldingsituations,the

narrowerrowsaregenerallyagreedtohaveaslightyieldadvantage.

Ontheotherhandinmoremarginaldrylandconditions,widerrowsoraskip-row

configurationhaveshownyieldresponsesinsomeyears.Singleskipsonrows75cmto1


i More information

KO’Keeffe(2006)Maize:

NSW planting guide

2006–07.NSWDPI

Primefact 267.

C Collis(2013)Lessons

fromtheUShelpmaize

enterprise.GRDC

GroundCoverIssue107.



http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0003/90273/maize-nsw-planting-guide-2006-07.pdf




http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-107-NovDec-2013/Lessons-from-the-US-help-maize-enterprise






December 2014



mhaveshownsomeadvantage(keepingthesamepopulationasasolidplant),whereas

double-skiprowsof1-mrowspacingaretoowide,withmoistureremainingattheendof

theseasonbetweentherows.

Growersmaybenefitfromtrialingdifferentrowconfigurationsbeforedecidingonone

patternbecausedifferentresultsmaybeseenbetweenhybridsanddifferentseasons.10

3.4.1 Plant populationsMaizegrowninAustraliaisplantedunderahugerangeofconditionsfromthehigh-input,

fullirrigationareasofsouthernAustraliatotheverymarginaldrylandareasofCentral

Queensland.Asaresult,plantingratesvaryfrom100,000to20,000kernels/hadepending

onenvironmentsandconditions.

Totalwaterusageinamaizecropisnotdirectlyrelatedtoplantpopulation,becausewater

islostbybothplantrespirationanddirectevaporationfromthesoil.Untilthecanopy

shadesthetotalground,lossestoevaporationwilloccur.

Higherplantpopulationsshadethegroundearlierandreducetheamountofwaterthat

iswastedbydirectevaporationwhilethesurfaceismoist.Withhigherpopulations,

plantsshadeeachothermore,whichreducesleaftemperaturesandtheamountofwater

transpiredbytheleaves.Higherplantpopulationswilldepleteavailablesoilwaterata

fasterrateandirrigationfrequencywillneedtobeincreased.Higherpopulationsspeedup

maturitybyupto7days.

Theprimaryfunctionofamaizecanopyistointerceptlight.Lightthatreachesthesoil

surfaceislost,orworsestillreducespotentialphotosynthesisandhenceyield(latitudeand

thereforedaylengthisnowbecomingincreasinglyimportant).Oncelightisintercepted,it

mustbeusedasefficientlyaspossibleandthisisafunctionofleafangle.Flathorizontal

leavesdothebestjobofinterceptinglightbutuseitleastefficiently.Verticalleavesare

poorestatinterceptinglightbutuseitmostefficiently.Theidealplanttypewouldhave

horizontallowerleavesanderectupperleaves.

Thephysicalmakeupoftheplanttellsusthatwithanestablishedpopulationof>60,000–

70,000plants/ha,competitionforlightbecomesjustasimportantasmoistureandnutrient

availability.Thisisamainreasonforbarrenplantsinhigherpopulationcrops,especiallywith

hybridsthathavemorehorizontalleavesthanverticalleaves.

Insummary,calculationofthecorrectplantpopulationshouldbebasedonthefollowing

variables:selectionofindividualhybrid—thismayalsoinfluencerowspacingandlonger

seasonhybridsgenerallyrequirefewerplantsthanshorterseasonhybrids;themarketyou

areaimingat—slightlylowerpopulationwillgiveabiggerkernelforthegritmarket,silage

growersmayconsiderafewmoreplantsforhigherdrymatterproduction;latitude;climate;

and planting time.


i More information

MRobertsonet al. (2003)

Improvingtheconfidence

ofdrylandmaizegrowers

inthenorthernregion

bydevelopinglow-risk

productionstrategies.

AustralianAgronomy

Conference.

Z Yang et al.(2010)

Effects of Pot Size on

GrowthofMaizeand

SorghumP.Australian

SummerGrains

Conference.

D George et al.(2010)

Optimisingphenotypes

fordrylandmaizein

northernNewSouth

Walesandsouthern

Queensland.Australian

SummerGrains

Conference.




http://www.regional.org.au/au/asa/2003/c/16/robertson.htm








https://www.grdc.com.au/uploads/documents/2010ASGCEditedPapersPDF/Yang_PotSize_edited_paper.pdf






https://www.grdc.com.au/uploads/documents/2010ASGCSummaryPapersPDF/George_OptimisingPhenotype_summary.pdf










December 2014



Whendoingthefinalcalculationtodeterminetheplantingratetoachievethedesired

establishedplantpopulation,youneedtoallowfor:

• actualseedgermination

• whetherthesoiltemperatureandmoistureoptimum

• whetheranygroundinsectsarepresent

• typeofplanterbeingusedanditsaccuracy

• groundspeedofplanter

Asaguide,areasonablefieldestablishmentis~80%,whichallowsforactualseed

germination(e.g.90%)and10%lossfortheothervariables.11

Manyfactorsincludingsoilmoisture,climaticconditions,soilfertility,hybridandenduse

determinethebestplantpopulationforacrop.Drylandcropsindrierareasshouldhave

lowerplantpopulationsthanirrigatedorhigh-rainfallareacrops(Tables4and5).

Quick-maturinghybridsproducesmallerplantsandsotheyshouldbesowninhigher

populations.Conversely,slow-maturingvarietiesgenerallyproducelargerplantssousually

growbestwhensownatlowerdensities.However,withinanymaturitygroup,hybrids

havedifferenttolerancestohighplantpopulations,withthemoretoleranthavingbetter

resistancetolodging,alowpercentageofbarrenplantsandgoodtimingofsilkingwith

pollenshedding.Silagecropsneedhigherpopulationsthangraincrops.SeeTable4below

forgeneralrecommendations.Refertoseedcompaniesforadditionalinformation.

Iftheonlyavailableplantingwindowwillexposethecroptohightemperaturesduring

tasselling,silkingandearlycobformation,reducingtheplantdensitycanreducemoisture

stressandmycotoxinrisk.

Maizeishighlyresponsivetoplantpopulationandplantuniformity,meaningthesowing

operationiscriticalforhighyields,socaremustbetaken.Precision-plantingequipment,

suchasvacuumseedmeteringsystems,ispreferred.Sowatauniformdepthto

ensureuniformemergenceandachievementofthetargetplantstand.Opportunitiesto

increasespeedatsowingshouldonlybeusedwheretheprecisionoftheoperationisnot

compromised. 12

Table 4: Recommended plant populations for grain and silage crops in NSW

Moisture availability No. of plants per ha

Grain Silage

Irrigated—allregions 60–80000 70–100000

Dryland

Coastal 45–55000 50–65000

Tablelands 40–45000 50–60000

NorthernPlains 20–30000










December 2014



Table 5: Recommended plant populations (no. of plants/ha) in Queensland.13

Thistableisaguideonly.Therecommendedpopulationforaspecificvarietyshouldbeobtainedfromtheseedcompany.Ifgrowingforsilage,usethehigherpopulationranges14

Dryland IrrigatedNorthQueensland: -Atherton,Tolga,Kairi -Kaban,Walkamin,Mareeba,Lakeland -Wettropicalcoast

45–55000 40 000 50 000

60 000 60 000

CentralQueensland 20–40000 50–80000

SouthBurnett 25–30000 55–70000

DarlingDowns-north 25–30000 60–75000

DarlingDowns-central/south 40–45000 60–75000

Moreton(Lockyer/Fassifern) 45–60000 60–75000

3.4.2 Planting rateTable6showsplantingrates(kg/ha)forvariousseedsizeswhenusing90-cmrowspacing.

Averageseedingratesarebasedon85%germinationrateand100%emergencerate.

Table 6: Sowing rates to achieve desired plant population using various seed sizes

Desired plant population per ha

Number of seeds per kg:Average seed spacing, 90-cm rows

2500 3000 3500 4000

Seed sowing rate kg per ha

15 000 7 6 5 4.5 63 cm

20 000 9 8 7 6 47 cm

25 000 12 10 8 7 37 cm

30 000 14 12 10 9 31 cm

50 000 24 20 17 15 19 cm

60 000 28 24 20 18 16 cm

Shoulddifferentspacingbeusedbetweenrows,thefollowingcalculationcanbeused:

• Plantingrate=desiredpopulation÷(no.ofseeds/kg×germination%×emergence%)

whereplantingrateisseedplanted(kg/ha);desiredpopulationisnumberofplantsperha

(e.g.40,000);no.ofseeds/kgisindicatedontheseedpack(e.g.3000);germination%is

indicatedontheseedpack(expressedasadecimal,e.g.85%is0.85);andemergence%

is,forexample,90%.

Workingexample:

• Plantingrate(kg/ha)=40,000/3000×0.85×0.90

• Plantingrate=17kgseeds/ha

Aready-reckonertoobtainemergencepercentage(%):

• precisionplanters60–90%

• otherplanterswithpresswheels50–70%

• otherplanterswithnopresswheels30–50%

• oruseafigurefromyourownexperience.








December 2014



Calculatingseedspacingalongtherow(thiscalculationisusedtocalibratetheseeddrillto

sowattherequiredrate):

• Distancebetweenseedsintherow(m)=10,000/plantingrate(kg/ha)×no.ofseeds/

kg×rowwidth(m)

Workingexample:

• Distancebetweenseedsintherow(m)=10,000/17×3000×0.9

• Distancebetweenseedsintherow=0.21m(or21cm)15

3.4.3 Row spacingRowspacingiscommonly75–110cm.Widthisultimatelydeterminedbytheavailable

planter,tractor,harvesterandotherequipment.Narrowrowsareanadvantagewhen

thereisgoodin-croprainfallorirrigation,highfertilityandhighplantpopulations.Insuch

conditions,narrowerrowswillusuallyproduceslightlyhigheryieldsbecauseplantsare

moreevenlyspaced.

FordrylandproductionindrierareassuchastheNorth-WestPlains,single-ordouble-skip

on100-cmrowsissuggestedsothatsoilmoistureisconservedforgrainfill.TrialsatMoree

suggestthat,inmoisture-stressedconditions,theremaybenoadvantageofdouble-skip

oversingle-skipconfigurationsbecauseoftheinabilityoflateralrootstoextractmoisture

fromthecentreofadouble-skip.Withskip-rowconfigurations,usethesametargetplant

populationasforsolidplanting.Thismeans,forexample,thatthein-rowplantpopulationin

double-skiprowswillbetwicethatinsolidplanting. 16

Plantingseedvariesfromyeartoyearbecauseofseasonalinfluencesandgrowing

conditions.Plantingseedcanbeboughtinsixcategories,allin72,000-kernelbags:small

flats,smallrounds,mediumflats,mediumrounds,largeflatsandlargerounds.

Mostvacuumplantershaveatolerancetoarangeofseedsizes,butitisadvisabletokeep

onhandarangeofplantingplates,asyourpreferredsizemaynotalwaysbeavailable.

Thesameseedsizecanvaryinkernelcountperkgfromyeartoyear,andairpressureon

vacuumplantersshouldbeadjustedaccordingly.17




i More information

RLNielsen(1997)

Standestablishment

variabilityincorn.Purdue

University.







http://www.agry.purdue.edu/ext/corn/pubs/agry9101.htm






December 2014



3.5 Sowing depth

Underidealconditions,asowing-depthrangeof3–6cmisrecommended,althoughif

soiltemperaturesarerelativelywarm,maizewillstillemergefromadepthofupto9cmif

moistureisavailable.Growersinthesouthernareas,whowaterupasopposedtoplanting

intopre-wateredfields,donotneedtoplantatthisdepthandmaychoosetosowtheseed

at~2–3cm.18

3.6 Sowing equipment

Precisionplantersarethemaintypeofplantersusedinthemaizeindustry,withverylittleuseof

traditionalcombinesorseeddrillswhereflutedrollersandcoultersgiveunevenseeddistribution.

Comparedtoothergraincrops,maizeisgenerallyplantedatamuchlowerpopulation,

anditisthereforecrucialtohaveevenplantstands,whichcanbeachievedwithprecision

planters(Figure1).

Inaddition,maizedoesnotcompensatebytilleringinthewaythatacropofsorghumdoes,

soitisessentialtogetanevenlyspacedcrop.

Otheradvantagesofprecisionplantersaretheevenplantingdepth,abilitytoapplystarter

fertiliserawayfromtheseed,andthefactthatinsecticideboxesandsprayingequipmenton

theplantermeansthatbothinsecticidesandherbicides/liquidfertiliserscanallbeappliedin

theoneoperation.Allprecisionplantersarefittedwithpress-wheels,whichenhanceseed–

soilcontact.

Newgrowerswithoutadequateplantingequipment,orgrowersnotusingprecision

planters,shouldconsiderusingacontractorwithaprecisionplanter.

Plantingspeedhasanimpactonthespacingoftheseed,andtheslowerthebetter.

Groundspeedsof5–6km/hareideal,causinglessseedbouncethanspeedsof8–10km/h.19

However,excellenttechnologyisavailablenowwith,plantersusingvSetstogetbettereven

establishment.

Figure 1: A precision-planted maize crop. (Photo: Pacific Seeds)










December 2014



3.6.1 Evenness of establishmentPrecisionplantersgivemoreevenplantspacingintherow.Itisimportanttoavoidseed

bounceinseedtubesandinseedfurrowstoavoidgapsandthickpatchesinarow.

Unevenplantestablishmentandunevenplantspacingbotheffectgrainsizeandyield

severely.Thisismorecriticalforgrittingmaizethanforfeedmaize.20




Section 4 MAIZE - Plant growth and physiology


December 2014



SECTION4

Plant growth and physiology

Abroadunderstandingofthegrowthofamaizeplantwillallowustoconsiderwhenthe

criticalgrowthstagesoccurandwhatthenutritionalandwaterrequirementsareatthose

times.

Often,farmersspendaconsiderableamountofmoneyonfertiliser,cultivationandwatering

theircroponlytoendupwithanaverageyield.Theyhaveusedtheoptimumlevelofinputs

buthavenotachievedtheoptimumyield,usuallybecauseofpoortimingofinputsorpoor

crop management.

Thiscanbeduetoalackofknowledge(orclearunderstanding)ofthegrowthhabitsand

requirementsofamaizecrop.Understandingamaizeplant’sdevelopmentanditscritical

growthstagesisessentialtoachievinghighyieldsandobtainingmaximumprofitability.

ThedevelopmentofamaizeplantanditsrequirementsareshowninFigure1.Allmaize

plantsfollowthesamegeneralpatternofdevelopment,butdifferencesinthetimetakenfor

thevariousgrowthstagesdependprimarilyonhybridmaturity(givensimilarconditions).

Thetimes,heightsandcommentsindicatedinFigure1areforahybridwithacomparative

relativematurity(CRM)of~120days.1

1 Growthpotential.Corngrowers’workshop.PioneerHi-BredAustralia.http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Corn_Workshop_Book.pdf

i More information

LJAbendrothet al.

(2011)Corngrowthand

development. Iowa State

UniversityExtensionand

Outreach.

Cornproduction.Growth

and development.

Iowa State University

AgronomyExtension.

Growthstageestimator.

Du Pont Pioneer.


http://www.dnalc.org/view/16955-Time-Lapse-of-Growing-Maize-Plants.html



http://www.dnalc.org/view/16955-Time-Lapse-of-Growing-Maize-Plants.html

https://store.extension.iastate.edu/Product/Corn-Growth-and-Development





http://www.agronext.iastate.edu/corn/production/management/growth/




https://www.pioneer.com/home/site/ca/agronomy/tools/growth-stage-estimator

https://www.pioneer.com/home/site/ca/agronomy/tools/growth-stage-estimator



December 2014



Figure 1:

Maturity

17 weeks

16 weeks

15 weeks

14 weeks

13 weeks

12 weeks

11 weeks

10 weeks

Silking

Tasseling

7 weeks

6 weeks

5 weeks

4 weeks

3 weeks

2 weeks

1 week

Emergence

% N less

than 1 less

than 1less

than 1less

than 1

2

4

6

10

12

16

15

9

11

13

15

11

10

14

11

7

2

less than 1less

than 1less

than 1

% P less

than 1

1

2

5

8

7

4

16

20

21

16

2

1

less than 1less

than 1less

than 1

% K

-K

-K

-K

-K

--

--

1

5

8

12

11

10

7

8

11

12

9

3

1

less than 1less

than 1

% Water

less than 1

1

2

3

5

6

5

4

2

1

less than 1

Weekly Requirements(as percentage of total need)Maize Development

Maize development. (Source: Pioneer)

4.1 Germination and emergence

4.1.1 Germination—VE stageWhenthemaizekernelisplantedinmoist,warmsoil,waterisabsorbedthroughthe

seedcoat(thisprocessiscalledimbibition)andthekernelbeginstoswell.Thekernel

accumulates~30%ofitsdryweightaswaterbeforeenzymaticactivityintheembryo

begins.

Enzymesactivategrowthintheembryo,andifconditionscontinuetobefavourable,the

radicleelongatesandemergesfromtheseedcoatwithin2or3days.Theplumulealso

beginstoelongate,andadditionalleavesbegintoforminsidethispartofthedeveloping

seedling.Thetiny,softleavesareenclosedinaspecializedleafstructurecalledthe

coleoptile,whichispointedontheendandabletogrowupwardthroughabrasivesoilto

bringtheleavestothesurface(Figure2).




December 2014



Figure 2: The germinating kernel. (Photo: Lowan Turton)

Figure 3: The developing seedling. (Photo: Lowan Turton)

Thefirstseedlingroot(theradicle)issoonfollowedbyseveralotherseminalorseedroots

(Figure3).Theseanchorthedevelopingseedlingandplayaroleinwaterandnutrient

uptake.Therootsthatarisefromthekernelarecalledtheprimaryrootsystem.

Theprimaryroots(seminalroots)growdirectlyfromthekernelandmaintaintheseedlingfor

thefirst2–3weeksuntilthepermanent(secondary)rootsystemdevelopsfromthecrownof

theplant.Thecrowncontainsthegrowingpointoftheseedlingandremains~3cmbelow

thesoilsurfaceuntil~3weeksafteremergence.




December 2014



Betweenthepointofattachmenttothekernelandthecrownisthemesocotyl(Figure3),a

tubular,white,stemlikepartsometimesconsideredthefirstinternode.Boththecoleoptile

andthemesocotylelongateasthetipofthecoleoptilemovestowardthesoilsurface.Once

thecoleoptilebreaksthesoilsurfaceandencounterssunlight,itstopsgrowingandthefirst

leafbreaksthroughthecoleoptile.Whenlightstrikesthecoleoptiletip,achemicalsignal

releasedfromtheemergedtiphelpstofixthedepthofthecrown,usually2–3cmbelowthe

soilsurface.Thedepthofthekernelisthusnotasimportantasthissignalindetermining

thedepthofthecrown.Thelengthofthemesocotylisnormallyequaltoabouthalfthe

plantingdepth,butifthekernelisplanteddeeplythenthemesocotylcanbemuchlonger,

sincethedepthofthecrownismoreorlessconstant.2

4.1.2 Emergence—VE stageThecoleoptileemergesfromthesoil6–10daysafterplanting,butthiscanbedelayedby

cooltemperaturesordrysoil.Assoonasthecoleoptiletipreachesthesunlight,itsplitsat

thetipandtwotrueleavesunfold(Figure4).Incloddysoilorinthepresenceofasoilcrust

orcertainherbicides,thecoleoptiletipcanrupturebeneaththesoilsurface,prematurely

releasingthefirstleaf.Manyoftheseplantsdie,becausetheleavesarenotstrongenough

topushthroughthesoil.

By7daysafteremergence,thenewseedlinghastwofullyexpandedleaves.Theprimary

rootsystemhasdevelopedenoughtomaketheplantindependentofthedwindling

foodsupplyinthekernel.Afterthefirsttwoleavesemerge,thenextleavesgrowupward

insidetheseleaves(i.e.upthroughthe‘whorl’)andunfoldattherateofaboutoneleaf

every3days,oraboutoneleafforeach65growingdegree-daysthataccumulate(see

Developmentbelow). 3

Figure 4: Emergence. (Photo: Kieran O’Keeffe)

2 KO’Keeffe(2009)Maizegrowth&development.PROCROPSeries,NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0007/516184/Procrop-maize-growth-and-development.pdf







December 2014



4.1.3 Factors affecting germination and emergenceGerminationandseedlingestablishmentarethefirstcriticaltimesinthelifeofthemaize

plant.Duringgerminationandearlygrowth,thekernelandseedlingneedoxygen,water

andadequatetemperatures.Theyalsoneedanenvironmentfreeofdisease,insectsand

damagingsubstancessuchassaltsorcertainherbicides.Ifthesoilistoocold,toowet,

ortoodry,germinationmaybeslowortheyoungseedlingmaydiebeforeitcanbecome

established.4

Moisture

Soilmoistureinfluencesthespeedofgermination.Germinationandemergencearerapidif

thesoilismoist.

Waterinjectionmayspeedgerminationbutmaynothelptheproblemofinsufficient

moistureintheseedbed.

Thechoicebetweenpre-sowingorpost-sowingirrigationdependsonsoilcharacteristics,

especiallysurfacecrusting.CropsgrowninthevariablesoilsofsouthernNewSouthWales

(NSW)arecommonlysownintoadryseedbedandthenirrigatedup.Thisworksbestwhen

cropsaresownonhillsorpermanentbedlayouts. 5

Waterlogging

Theyoungplantisverysusceptibletodamagebywaterloggingbecausethegrowing

pointremainsbeneaththesoilsurfaceforthefirst3weeks.Iftemperaturesarehigh,

waterloggingdamagecanbeparticularlysevereandcanretardgrowth. 6

Temperature

Germination

Germinationdependsontemperature.Germinationisgreatlyreducedifthesoiltemperature

is<10°C.Maizeshouldbesownwhenthesoiltemperature(atsowingdepth)at09:00

(9am)(EDST)is>12°Candincreasesoverthefollowingdays.Attheserelativelylow

temperatures,seedlingemergencewillbeveryslow(≥14days);at25°C,seedlingsemerge

in4–5days.

Inirrigatedsituations,cropsthataresownintomoisture(frompre-irrigationorstoredrainfall)

arelikelytoexperiencewarmersoiltemperaturesandhencequickeremergencethancrops

thatareirrigatedup.










December 2014



Development

Temperatureiscriticallyimportantinthedevelopmentofthemaizeplant.Astemperature

increasesinarangeof10°–30°C,thegrowthrateincreases.Below10°Cthereislittle

growth,and>30°Cthegrowthratelevelsoff.

Thislinearresponsemeansthatthedevelopmentofthecropcanbepredictedbyadding

upthenumberofthermalunitsthatthecrophasexperiencedsinceitwasplanted.The

thermalunitsusedformaizedevelopmentarecalled‘growingdegree-days’,or‘modified’

growingdegree-days.

Growingdegree-daysare‘modified’wheneitherthedailyminimumorthedailymaximum

temperatureisoutsidethe10°–30°Crange.Ifthisoccurs,thevalues10and30are

substitutedastheminimumandmaximumvalues,respectively. 7

Table1showstheestimatednumberofgrowingdegree-daysforamid-maturityhybrid.

Figure5showstherelationshipbetweenthegrowthstageandthermaltime(=numberof

growingdegree-days)inthemaizeplant.

Table 1: Estimated number of growing degree-days for the development stages for a mid-maturity hybrid

Stage Number of growing degree-days

Emergence 84

V2 129

V6(tasselinitiation) 282

V10 429

V14 573

VT(tasselemergence) 657

Silking 795

R4(doughstage) 1087

R5(dentstage) 1361

R6(physiologicalmaturity) 1518






December 2014



Figure 5:

Kernel development and growth

Anthesis

Kernel primordium initiation

Ear shoot development and growth

Tassel development

Tiller/shoot abortion

Internode elongation

Tiller/shoot growth and appearance

Tiller bud primordium initiation

Leaf growth and appearance

Leaf primordium initiation

Growth stage and thermal time

Germination

200

VE V4 V8 V12 V16 VT/R1 R2 R3 R4 R5 R6

400 600 800 1000 1200 1400 1600 1800TT

• As temperature increases, the growth rate increases.

• Below 10oC there is little growth.

• Above 30oC the rate slows.

Relationship between growth stage and thermal line (growing degree-days) in the maize plant. (Source: McMaster et al. 2005)

Oxygen

Oxygenisessentialtothegerminationprocess.Kernelsabsorboxygenrapidlyduring

germination,andwithoutenoughoxygentheydie.Germinationisslowedwhenthesoil

oxygenconcentrationis<20%.Duringgermination,watersoftenstheseedcoattomakeit

permeabletooxygen,sodrykernelsabsorbalmostnooxygen.

Kernelsplantedinwaterloggedsoilscannotgerminatebecauseofalackofoxygen.Itis

commonlythoughtthatinverywetconditionskernels‘burst’,butinfact,theyrunoutof

oxygenanddie. 8

Nutrition

Becausethekernelhasstoredwithinitalltheessentialnutrientsthatitneedstobegin

growing,nutrientshortagesarenotanissueinthefirstfewdays.However,astheroots

begintotakeovernourishingtheyoungplant,shortagesofelementssuchasnitrogen(N)

andphosphorus(P)canslowgrowthanddevelopment.

Asoiltestshouldbedonebeforesowingtomeasuresoilnutrientsandcalculatefertiliser

requirements.

Bandingfertiliseratsowingensuresthatthecropusestheavailablenutrientsfromavery

earlystageofrootdevelopment.Anaddedadvantageofband-appliedfertiliserover

broadcastfertiliseristhatthenutrientsremaininanavailableformforalongertime.






December 2014



Bandfertilisationatsowingtimeispossiblewithmodernmaizeplanters.Applymixed

fertilisers(N,Pand/orpotassium(K))inabandplaced5cmtothesideoftheseedand5

cmbelowit.Thispreventsthefertiliserfrom‘burning’thedevelopingseedling. 9

Seedbed

Seedbedpreparationisalsoimportanttoemergence.Maizekernelsneedgoodsoilcontact

forgermination.Irrigatedmaizeisusuallysownonpermanentbedswithtworowsperbed,

usingprecisionplantersandpress-wheels(Figure6).

Inirrigatedfields,oldhillsorbedswithcompactedsoilorhardpansshouldberipped

(centre-busted)orchisel-ploughedtoensuregoodrootgrowthandwaterinfiltration.Where

soilcompactionproblemsaresuspected,digabackhoepittoinspecttheprofileofthe

root-zone.

Tillageoperationsperformedunderwetconditionscancauseserioussoilcompaction

andsmearing.Stubbleretentioncanreducesoilstructuralproblemsorsurfacecrusting.

However,ifthestubbleiskept,adequateNisneededbecausesomeNistiedupasthe

stubbleresiduesdecompose.Mulchingstubbleearlyandgettinggoodsoil–stubblecontact

willallowtimeforbetterstubbledecompositionandreducetheimpactofNtie-up. 10

Figure 6: The sowing operation. (Photo: Kieran O’Keeffe)

Sowing depth

Seedsshouldbesownatadepthwherethereissufficientsoilmoistureforseedling

emergence.Theidealdepthis4–5cm,althoughseedsmaybesownasdeepas9cm.

Deepersowingslowsseedemergence.Itdoesnotcreateadeeperrootsystemorenhance

theplantsstandingability.

Thesowingdepthshouldbeuniformtoensureevenemergenceandauniformplantstand.

Thesowingoperationiscriticalforhighyields,socaremustbetaken.Plantstandvariability

(distancebetweenplants)hasadirectnegativeimpactonyield,asshowninFigure7. 11










December 2014



Figure 7:

Gra

in y

ield

(kg

ha-1

)

12,500

12,000

11,500

11,000

10,500

10,000

y = –54.622x + 12346 R2 = 0.9644

Actual plant spacing variability (cm)

250 5 10 15 20

• The data points represent treatment plant spacing variability over nine sets of experiments.

• The results are from large-scale field research in Indiana, USA.

• As the distance between plants increases, grain yield decreases

Relationship between maize grain yield and measured plant spacing. (Source: Nielsen 2006)

Plant population

Eachhybridgrowninaparticularlocationwillhaveanoptimumrangeinplantpopulationto

maximiseyield.

Between70%and90%oftheseedsownwillproduceaplant.Depthofsowing,disease,

crusting,moistureandotherstressesallreduceplantestablishment.Fieldestablishmentis

unlikelytobe>90%.

Whencalculatingasowingrate,allowanextra5–10%forestablishmentlossesunder

normalgrowingconditions.SeeTable2.Anevenplantspacingisimportanttomaximise

yields(Figure8).

Table 2: Recommended plant populations (source: NSW DPI)

Moisture availability

No. of plants per ha

Grain Silage

Irrigated,allregions 60–80,000 60–100,000

Dryland

Coastal 45–55,000 50–65,000

Tablelands 40–45,000 50–60,000

NorthernPlains 20–30,000 –

i More information



guide 2014. NSW DPI

Management Guide.








December 2014



Figure 8: Even spacing between plants is important to maximise yields. (Photo: Kieran O’Keeffe)

Thefollowingfactorsshouldalsobeconsideredwhencalculatingatargetplantpopulation.

End use

Greenfoddercropsarethemostdenselysown,followedbycropsforsilage,andthengrain

crops.Non-irrigatedcropsindrierregionsshouldhavelowerplantstanddensitiesthan

cropsinirrigatedorhigh-rainfallareas.Iftheonlyavailableplantingwindowwillexposecrop

tohightemperaturesduringearformation,reducingplantingdensitycanreducemoisture

stressandmycotoxinrisk.

Soil fertility and available moisture

Fertilesoils(includinghighlyfertilisedsoils)supportdenserplantstandsthandolessfertile

soils.Highfertilitycanpartlycompensateforlowavailablemoisturelevelsbecausewell-

fertilisedplantsuseavailablemoisturemoreefficiently,probablyaresultofgreaterroot

development.

Type of hybrid sown

Slow-maturinghybridsgenerallyproducelargerplants,sotheyusuallygrowbetterifsown

atalowerdensitythandofastermaturinghybrids.However,hybridswithinamaturitygroup

havedifferingtolerancesofhigherplantdensity.Themoretoleranthybridsshowresistance

tolodging,alowpercentageofbarrenplantsandgoodsynchronisationofsilkingwith

pollenshedding.

Planting pattern

Rowsareusuallysown75–110cmwide,althoughthewidthisultimatelydeterminedby

thetractors,harvestersandotherequipmentavailable,whichmustbeabletopassthrough

thecropwithoutthewheelsdamagingtherows.Narrowerrowsareprobablyanadvantage

whenthereisahighplant-standdensityandhighlevelsofsoilfertility,becauseplantswithin

therowcanthenbemorewidelyspaced.

Evidencesuggeststhatmakingtheplantspacinguniformwithintherowisveryimportant

formaximisingyield(refertoFigure7). 12






December 2014



4.2 Vegetative growth

4.2.1 Vegetative Growth

V1–V2 stage

Thesegrowthstagesoccurabout1weekaftertheplantemerges(Figure9).Oneortwo

leavesarevisibleonthestemandtheprimaryrootsystemisstillrelativelysmall.

Althoughtheplantisusingonlysmallamountsofnutrients,theyneedtobeincontactwith

therootsystem.Bandedfertiliserplacedunderneaththeseedwillalloweffectiveuptake. 13

Figure 9: A V2 plant. (Source: Ritchie et al. 1992)

V3–V5 stages

Twoweeksaftertheplantemerges,theV3stagebegins(Figure10).Theseedlingroot

systemhasstoppedgrowingandthenodalrootsnowformthemajorpartoftheroot

system.Roothairsarepresentonthenodalroots.Therootsofthesecondwhorlare

elongating.

Cultivationtooneartheplantwilldestroysomeofthepermanentrootsystem.

Leafandearshootsarebeinginitiated,andthisinitiationwillbecompletebyV5(whenthe

potentialearshootnumberisdetermined).

AlsobyV5,amicroscopicallysmalltasselisinitiatedatthegrowingpoint.Theplantis~20

cmhighwhenthetasselisinitiated,butthegrowingpointisstillat,orjustunder,thesoil

surface.However,soiltemperaturecanaffectthegrowingpoint.Lowsoiltemperaturesat

thisstagecanreducenutrientavailabilityandslowdevelopmentalstages.

Frostorhailmaydestroytheexposedleavesbutwillnotdamagethegrowingpointbelow

thesoilsurface.

Leafdamageatthistimeusuallyresultsinverylittlereductioninfinalyield.






December 2014




Competition with weeds for water, nutrients and light

Atthisstage,weedscompeteforwater,nutrientsandlight.Chemicals,cultivationand

higherplantpopulationsorcroprotationusedincropplanningcanreduceweedpressure

andlimitthecompetitiontothemaizecrop. 14

Ear initiation

Theear,orfemalefloweringstructure,isacentralcobwithacylindricallyarrayedgroup

offemaleflowers.Eachflowerconsistsofanovarywithanattachedsilk(averyelongated

style)andiscapableofproducingakerneliffertilisedsuccessfully.Onawell-developedear,

700–1000potentialkernelsorovulesarearrangedonthecob,withabout35perrowand

12–24rows.

Thetimingofearinitiationvarieswithmaizegenetics.Ageneralguidelineistodetermine

whichnodecontainstheprimaryear(theeartobeharvested)andthensubtract7togive

thestagenumber.Thiswillgiveareferencepointastowhenearinitiationstarted.TheV

stagewhenearinitiationstartedisalsowhenthenumberofkernelrowsaroundtheearwas

beingestablished.

Forexample,themaizelineinFigure10positionstheprimaryearattheV14node.This

wouldmeanthatearinitiationbeganat,orverynear,theV7stage.

Thelocationoftheprimaryearalsovarieswithmaizegenetics.Themaizeparentlinein

Figure11hasaCRMof103.TheprimaryearislocatedontheV14node.Ingeneral,maize

lineswithaCRMof103–118willproducetheprimaryearontheV13orV14node.Parent

linesofearliermaturitywillplacetheprimaryearonalowernode,suchastheV12node,

whereasmaizelinesoflongermaturitymayplacetheprimaryearonahighernode. 15



i More information

AMMassignam et

al.(2001)Canopy

architectureandnitrogen

utilisationforbiomass

production:thecontrast

between maize and

sunflower.Australian

AgronomyConference.

IKDJayaet al.(2001)

Modificationofwithin-

canopymicroclimatein

maize for intercropping

inthelowlandtropics.

AustralianAgronomy

Conference.




http://www.regional.org.au/au/asa/2001/6/b/massignam.htm








http://www.regional.org.au/au/asa/2001/6/b/jaya.htm









December 2014



Figure 11: Development of the primary ear at node 14. (Photo: Antonia Perdomo, Pioneer Hi-Bred)

Establishing the number of kernel rows around the ear (V5–V8 stage)

Dependingonitsrelativematurity,themaizeplantdeterminesthemaximumnumberof

rowsaroundtheearbetweentheV5andV8stagesinitslifecycle.

ThemeristematicdomeatthetipoftheearinFigure11indicatesthatthedevelopingearis

stillproducingnewrowsofovulesalongitslength.Theuppertwo-thirdsoftheearshows

aseriesofsinglerowsdevelopingovules.Theseovuleseventuallydividetoproduceapair

ofrowsofovulesfromeachsinglerow.Thispairedformationisvisiblenearthebaseofthe

ear.Thisdivisionintopairsexplainswhyamaizeearalwayshasanevennumberofkernel

rowsaroundit.

Themaximumnumberofovulesthattheentiremaizeearwillproducewillbedetermined

afteraboutfourmoreVstages.

Establishmentofthenumberofkernelrowsaroundtheearisacriticaleventandis

susceptibletoenvironmentalstress.Knowingwhenthiseventoccurshelpstoestablisha

‘timewindow’whenlookingforareason.Forexample,ifanearhas12kernelrowsaround

itinsteadofthenormal16,thenthestressfactorthatcausedthiseventwaspresentat

approximatelyV7. 16

V6 and V7 stages

Approximately3weeksaftertheplantemerges,theplantisattheV6stage.Theroot

systemiswelldistributedinthesoilanditextendsabout45cmdeepand60cmwide.The

thirdrootwhorliselongating.Thegrowingpointisabovethesoilsurfaceandrapidstem

elongationbegins.

Theplantisnowabsorbinggreateramountsofnutrients.Row-appliedfertiliserisless

criticalnow,asnodalrootshavespreadthroughoutthesoil.Nitrogencanbeside-dressed

uptoV8stageifitisplacedinmoistsoilandexcessrootpruningandinjuryofaboveground

plantpartsareavoided.






December 2014



Figure12showsatasselinaV7plant.Thisisacriticalstageforyieldwhenthemaizeearis

settingthemaximumnumberofkernelrowsaroundtheear. 17

Figure 12: Tassel of a V7 plant. (Source: Ritchie et al. 1992)

Establishing kernel numbers (V7–pollination)

FromaboutV7stageuntilpollination,themaizeplantisdeterminingthelengthoftheear

andthenumberofkernelsalongtheear.Ovulesnearthebaseoftheeardevelopfirst,and

newerovuleswillcontinuetoformasdevelopmentprogressestowardsthetipoftheear.

Afterthemaizeplanthasestablishedthemaximumnumberofovules,theenergy,nutrients

andwatertosustainthesedevelopingovulesmustbesupplied.Ifresourcesareadequate,

ovulesalongtheentireearwilldevelopsufficientlytoproducesilksandbereceptiveto

pollen.Ifresourcesarelimited,selectedovuleswillbesacrificedtoallowthemaizeplantto

adequatelysupporttheremainingviableovules.Whichovulesaresacrificeddependson

theamount,typeanddurationofthestress.

Withlongertermgeneralstress,ovulesnearthetipoftheeararesacrificed,resultingin

viableovulesonlyatthebaseofthedevelopingear.Ovulesnearthebaseoftheearare

morelikelytoremainviablebecausetheyaremoredevelopedandareclosertothesource

ofnutrientsupply.Iftheenvironmentalstressisveryshortbutveryintense,theovulesthat

aresacrificedmaybeanywherealongthemaizeear.

Veryshortears,called‘beercan’ears(Figure13),appeartobeduetoacombinationof

environmentalstresses—possiblecoldstresscoupledwithdroughtstressduringacritical

stageinovuleformation. 18








December 2014



Figure 13: ‘Beer-can’ ears. (Source: Strachan 2001)

V8 and V9 stages

Approximately4weeksaftertheplantemerges,itreachestheV8stage.

Thefourthwhorlofnodalrootsiselongating.Severalearshootsarepresent.Apotential

earshootwillformateveryabovegroundnodeexcepttheuppersixtoeight.Initially,each

earshootdevelopsfasterthantheoneabove,butgrowthofthelowerearshootsslows.

Onlytheupperoneortwoearshootseventuallyformharvestableears.Highestyieldsare

obtainedwithonecobperplant.

Prolifichybridstendtoformmorethanoneharvestableear,especiallyatlowerplant

populations.

Nutrientdeficienciesatthisstagewillrestrictleafgrowth,removalofalltheunfurledleaves

oftheplant(byfrostorhail)mayresultin10–20%reductioninfinalgrainyield.

Waterloggingatthisoranyearlierstage,whenthegrowingpointisbelowtheground,can

killthemaizeplantsinafewdays,especiallyiftemperaturesarehigh. 19Figure14showsa

V9plant.







December 2014



V10 and V11 stages

Approximately5weeksaftertheplantemerges,theV10stagebegins.Themaize

plantrapidlyaccumulatesbothnutrientsanddrymatter(Figure15).Thetimebetween

appearancesofnewleavesisshortened,withanewleafnowappearingevery2–3days.

Demandforsoilnutrientsandwaterishighinordertomeettheneedsoftheincreased

growthrate.Moistureandnutrientdeficienciesatthisstagewillmarkedlyinfluencethe

growthanddevelopmentoftheears.Fertiliserisneededneartheroots,especiallyPandK,

whichdonotmoveinmostsoils.

Twoyieldcomponents—potentialnumberofkernelsandearsize—arebeingdetermined

duringtheperiodfromV10toV17.

ThelengthoftimefortheplanttodevelopthroughstagesV10–V17affectsharvestable

yield.Early-maturinghybridsnormallyprogressthroughthesestagesinlesstimeandhave

smallerearsthanlatermaturinghybrids.Therefore,higherplantpopulationsareneededfor

earlierhybridstoproducegrainyieldssimilartothoseofmid-tolate-maturityhybrids. 20

Figure 15:

% o

f d

ry m

atte

r in

the

pla

nt

100

90

80

70

60

50

40

30

20

10

0Ve0 20 40 60 80 100 120

V6 V12 V18 R1 R2 R3 R4 R5 R6

Sept Oct Nov Dec Jan

Grain

Cob, shank, silks

Husks, lower ear shoots

Stalk, tassel

Leaf sheaths

Leaves

Dry matter accumulation at various stages in the maize plant. (Modified Ritchie et al. 1992)

V12 and V13 stages

Approximately6weeksaftertheplantemerges,V12stagebegins(Figures16,1718).

Braceroots(Figure17)aredevelopingfromthefifthnodeandthefirstabovegroundnode.

Cultivationofplantsatthistimewilldestroysomeoftheplantroots.

BytheV12stage,thepotentialnumberofkernelrowsandthepotentialnumberofovules

isestablished.Figure16showsanearattheV12stagefromthesamemaizeparentlineas

thatinFigure11.Themeristematicdomeisnolongerpresent,soovuleformationisnow

complete.Pairedovuleformationisapparentalongnearlytheentirelengthoftheear.






December 2014



Ifanearhasthepropernumberofkernelrowsaroundtheearbuttheearisshorterthan

normal,thensomestresswhilethemaizeplantwasaroundtheV12developmentalstage

mayhaveoccurredtocauseit. 21

Figure 16: Development of the primary ear: V12 stage. (Photo: Antonio Perdomo, Pioneer Hi-Bred)

Figure 17: Brace roots. (Source: Ritchie et al. 1992)

Figure 18: Left: plant at V12. Right: the top ear shoot is smaller than the lower ear shoots, but many of the upper ears are close to the same size. (Source: Ritchie et al. 1992)






December 2014



V14 and V15 stages

About7weeksaftertheplantemerges,V14begins.ThemaizeplantatV15(Figure19)is

only12–15days(~5Vstages)awayfromthestartofreproductivegrowth(R1,‘silking’).

Thisvegetativestateisthemostcriticalperiodofkernelyielddetermination.Thenumberof

ovulesthatdevelopsilks,andthusthenumberofkernels,isbeingdetermined.Anyinjury

ornutrientormoisturedeficiency(suchashailorinsects)mayseriouslyreducethenumber

ofkernelsthatdevelop.Thetasselisnearfullsizebutnotvisiblefromthetopofthelead

sheaths.Silksarejustbeginningtogrowontheupperears.Upperearshootdevelopment

hassurpassedthatoflowerleafearshoots.Anewleafstagecanoccurevery1–2

days.Bracerootsfromthesixthleafnodearedevelopingandthepermanentrootshave

continuedtoelongateandproliferate,eventuallyreachingadepthofabout100cmand

spreadinginalldirections.Insomehybrids,bracerootswillalsodevelopfromtheeighth

andninthleadnodesorevenhigher. 22

Figure 19: Plant at V15. (Source: Ritchie et al. 1992)

V16 and V17 stages

Approximately8weeksaftertheplantemerges,itisenteringthelatevegetativestagesif

ithasnotalreadydevelopeditstotalnumberofplantleaves.Duringthistime,plantstress

cangreatlyaffectyield.Moisturestress2weeksbeforeoraftersilkingcancausealarger

reductioningrainyield.Thisisalsotrueforothertypesofenvironmentalstresses(hail,high

temperature,nutrientdeficiencies).The4-weekperiodaroundsilkingisthemosteffective

timeforirrigationifwatersupplyisshort.Thetipsoftheupperearshootsmaybevisibleat

thetopoftheleafsheathsbyV17inhybridsthatdevelop>16leaves.Thetipofthetassel

mayalsobevisiblebyV17inmoreprolificallyleafinghybrids. 23








December 2014



V18 or VT stage

Thevegetativeplantisreachingfullsizeinhybridswithprolificleafing(Figure20).Silksfrom

thebasalearovuleshavebeenthefirsttoelongate,followedbythesilksfromtheear-tip

ovules.Bracerootsarenowgrowingfromabovegroundnodes.Thesebracerootsprovide

supporttotheplantandobtainwaterandnutrientsfromtheuppersoillayersduringthe

reproductiveplantstages.Eardevelopmentiscontinuingrapidly,withtheplantonly1week

awayfromviablesilking.Stressintheselatervegetativestagescandelaythebeginningof

pollenshed.Ifpollenshedisdelayed,plantsmaydelaysilkinguntilpollenshedispartlyor

completelyfinished.Ifovulesareunfertilised,kernelswillbemissingontheear,especiallyat

thetip. 24

Figure 20: Left: silks emerging in the later V stages. Right: upper ear shoot development. (Source: Ritchie et al. 1992)

4.2.2 Factors affecting vegetative growth

Moisture

Moisture stress

Eventhoughmaizemakesefficientuseofwater,itisconsideredmoresusceptibleto

moisturestressthanothercrops.Thisispartlybecauseofitsunusualflowerstructure,with

separatemaleandfemalefloralorgans,andpartlybecauseallthefloretsonasingleear

developatthesametime.Ifmoisturestressoccursduringtheirdevelopment,allwillbe

affected.

Theresponseofmaizetowaterstressvariesaccordingtothestageofdevelopment.One

visiblesignofmoisturestressisrollingoftheleafmargins(Figure21).

Figure 21: A moisture-stressed crop. (Photo: Paul Newell)






December 2014



Duringtheseedlingstage,moisturestressislikelytoreducesecondaryrootdevelopment.

Duringthefirst4weeksofgrowth,moisturestresscanresultinsmallercobs.

Duringstemelongation,leavesandstemsgrowrapidlyandneedadequatesuppliesof

watertosustainrapiddevelopment.Water-stressedplantsareshorterwithsmallerleaves

andlessleafarea.

Moisturestressisparticularlydetrimentaltograinyieldifthestressoccursaftertassel

initiation,atflowering,andduringmid–lategrainfill.

Figure22showsthatthewaterneedsincreaserapidlyfrom~2weeksbeforetasselandear

appearanceuntil~2weeksafterthefullsilkingandthendecreaserapidly.

Stressatfloweringandpollinationcanresultinunfilledkernelsonthecob.Thiscanreduce

grainyieldby6–8%eachdaytheplantisstressed.Iftheplantisstressedafterflowering,

kernelsizeisreducedandtheriskofmycotoxincontaminationincreases.

Figure 22:

Dry

wei

ght

wat

er n

eed

Days after emergence

Water requirement

14 28 42 56 66 78 90 102 114 126

Dry weight

Tass

el a

ppea

ranc

e

Silk

app

eara

nce

Blis

ter

Ear

ly d

ent

Full

dent

• Maximum water use occurs from 2 weeks before tassel and ear emergence until 2 weeks after full silking

• Stress at flowering and pollination can result in a 6% to 8% yield loss for every day the plant is stressed.

Maize plant water requirements at various times after sowing. (Source: Growing maize for profit, Pioneer Hi-Bred)

Waterlogging

Maizeisverysensitivetowaterlogging.Waterloggingcauseslowsoiloxygenconcentration,

whichlimitsrootfunctionandsurvival.TheavailabilityofNandothernutrientsmaybe

reducedbywaterlogging,whichslowstherateofleafgrowthandacceleratesleafdeath.

Thisreducesyieldtoadegreedependingonthegrowthstageatwhichthewaterlogging

occurs.

Waterloggingthatoccurswhenthegrowingpointisbelowgroundcankilltheplants,

especiallyiftemperaturesarehigh.Waterloggingatlaterstages,whenthegrowingpointis

abovethesoilsurface,isnotasdetrimental. 25






December 2014



Irrigation

Maizeistypicallyirrigatedbyfurroworfloodirrigation,butsprinkler(lateral-moveand

centre-pivot)irrigationanddripirrigationsystemscanalsobeusedtogrowhigh-yielding

maizecrops.Irrigationsystemsvaryintheirefficiency,butinallsystems,someofthe

waterappliedtothecropislostasrunoff.Somemayalsodrainthroughthesoiltoadepth

beyondtheroots,andsomeevaporatesfromthesoilsurface.Althoughtherearemany

factorsaffectingirrigation-systemefficiency,furrowirrigationis~70–80%efficient,spray

irrigation~85–90%efficient,anddripirrigation~90–95%efficient.

Whenmaizeisgrownunderirrigation,waterloggingisalwaysapotentialissue,especiallyin

theearlystagesofcropdevelopmentwhenthegrowingpointisbelowthesoilsurface.For

thisreason,manycropsaregrownonbedsor1-mhills.Onfree-drainingsoils,maizecan

stillbegrownontheflatusingborder-checklayouts,butcaremustbetakeninwetseasons

nottowaterlogtheplant.

Frequency

Howoftenyouirrigate(referredtoas‘scheduling’)dependsonmanyfactors,including:

• soiltype

• temperature

• rainfall

• evaporation

• wind

• humidity

• stageofcropgrowth

Irrigation scheduling tools

Loggersthatmonitormoistureatdifferentdepthsthroughouttheprofile(suchas

EnviroSCANandC-Probe)haveallowedaccurateandcontinuoussoilmoisturemonitoring

(Figure23).Thistechnologyalsoallowsusersaccesstotheinformationthroughwireless

communication,sosoilprofilescanbemeasuredfromcomputerssomedistanceaway.

Otherschedulingsystemsbasedonweatherdata(suchastheNSWDPIWaterwatch

service)areavailableinmajorirrigationareas.Figure24showsthesoilmoistureprofilesofa

maizecropontheLiverpoolPlains,detectedbyprobe,andFigure25showstheestimated

irrigationrequirementsforahigh-yieldingcropatGunnedah.

Figure 23: Soil moisture monitoring is an important tool in minimising crop stress. (Photo: Kieran O’Keeffe)




December 2014



Figure 24:

0

–20

–40

–60

–80

–100

–120

120

100

80

60

40

20

0

Days from sowing

Days from sowing

0 20

deficit

rain

probe

40 60 80 100 120 140 160

0 20 40 60 80 100 120 140 160

Def

icit

(mm

) Rain (m

m)

Rain (m

m)

8 L

Irr Irr Irr

9 bars

DoughTassel

Tassel

7.5 bars7.5 bars

Silk

0

–20

–40

–60

–80

–100

–120

120

100

80

60

40

20

0

Def

icit

(mm

)

8L

Irr Irr Irr

9 bars 10.5 bars

20 bars DoughTassel

Soil moisture profiles for a maize crop on the Liverpool Plains, NSW, in the 1989–90 season. Top: a crop irrigated on schedule (90 mm deficit) just before tasselling. Bottom: a crop that suffered serious stress at tasselling (115 mm deficit) and a further stress at dough stage. (Source: Kaiser et al. 1997)

Figure 25:

12

10

8

6

4

2

0

Probability %

0 20 40 60 80 100

Irri

gat

ion

req

uire

men

ts (M

L/ha

)

Estimated irrigation water requirements for a high-yielding crop at Gunnedah based on historical weather data and assuming an irrigation efficiency of 75%. In 50% of seasons, 6.8 ML/ha is needed. In 20% of seasons (1 in 5 years), about 8 ML/ha is needed. The estimates include irrigation water needed to replenish end-of-season soil water deficits. (Source: Kaiser et al. 1997)




December 2014



Irrigation frequency

Inlandcropswithoutraingenerallyrequire1irrigationevery10–12daysduringtheflowering

andgrain-fillingstages.Hotdryweathercanresultintheirrigationintervalshorteningto

6–7days.CropsinthenorthofNSWandsouthernQueenslandmayneed5or6‘in-crop’

irrigations,whereasRiverinacropsmayneed10or11irrigations,dependingonthesoil’s

water-holdingcapacityandthevariety. 26

Nutrition

Acceptableyieldsofgrainorsilagerequirehighlevelsofsoilfertility.Bothrequirethemain

essentialnutrients(N,PandK)(Figure26),althoughasilagecropremovesmoreofthese

nutrients,especiallyK,fromthecroppingsystem.Maizealsorequiresatleast10other

minorortraceelementsfornormalplantgrowthanddevelopment.

Zincisoneofthesetraceelementsessentialformaizegrowth.Zincdeficienciescan

commonlyoccurinmaizegrownonheavyclayalkalinesoils.SeeNSWDPISummer crop

production guide for more information.

Theyoungplanttakesupsmallamountsofnutrients,butwithgrowth,thenutrientuptake

rapidlyincreases(Figure27).

Figure 26:

100

90

80

70

60

50

40

30

20

10

0

weeks after emergence

K N P dry weight

181614121086420

% o

f to

tal u

pta

ke

Uptake of nitrogen (N), phosphate (P), and potassium (K), and dry weight accumulation. (Source: Colless 1992)


i More information


growers’workshop.

Pioneer Hi-Bred

Australia.











December 2014



Figure 27:

Maturity

17 weeks

16 weeks

15 weeks

14 weeks

13 weeks

12 weeks

11 weeks

10 weeks

Silking

Tasseling

7 weeks

6 weeks

5 weeks

4 weeks

3 weeks

2 weeks

1 week

Emergence

% N less

than 1 less

than 1less

than 1less

than 1

2

4

6

10

12

16

15

9

11

13

15

11

10

14

11

7

2

less than 1less

than 1less

than 1

% P less

than 1

1

2

5

8

7

4

16

20

21

16

2

1

less than 1less

than 1less

than 1

% K

-K

-K

-K

-K

--

--

1

5

8

12

11

10

7

8

11

12

9

3

1

less than 1less

than 1

% Water

less than 1

1

2

3

5

6

5

4

2

1

less than 1


Requirements of major nutrients and water. (Source: Colless 1992)

Nitrogen

ThedemandforNincreasesdramaticallyabout40daysafterseedlingemergence.Before

this,theplantshavetakenupabout18–20%oftheirtotalNrequirement.However,bythe

endofsilking,theyshouldhave75%oftheirtotalrequirement.

Figure28showstheeffectsofdifferentNtreatmentsoneardiameter,earlength,and

numberofkernelsperear.Early-seasonstresscaninfluenceeardevelopment.Adeficiency

inNbeforeV8(treatmentN1inFigure28)causedanirreversibledecreaseineardiameter

andearlength,aswellasnumberofkernelsperear.FromtreatmentN1,weseethatifNis

notapplieduntilafterV8,thereisasignificantyieldreduction;eventhoughNwassupplied

fortherestoftheseason,thisdidnothelpincreasetheyield,becausetheearparameters

hadbeensetearlier.




December 2014



Figure 28:

Ear

dia

met

er (c

m) 4.6

4.5

4.4

4.3

4.2

4.1

4.0N1 N2 N3 N4 N5 N1 N2 N3 N4 N5 N1 N2 N3 N4 N5

cbc

aba

a

Nitrogen treatment

Ear

leng

th (c

m)

20

18

16

14

12

10

c

abb

a

Nitrogen treatment

a

Num

ber

of

kern

els

ear-1

550

500

450

400

350

300

c

a

bc

a

Nitrogen treatment

ab

• Ear diameter and weight are set before V8.• A deficiency in nitrogen before V8 decreased ear diameter and ear length

Effects of different nitrogen treatments on ear diameter, ear length, and number of kernels per ear. N1, Withholding N supply from seedling to V8; N2, withholding N supply after V8; N3, withholding N supply after silking; N4, withholding N supply from 3 weeks after silking to physiological maturity; N5, continuous N supply from emergence to physiological maturity (control).Columns with the same letter within each parameter are not significantly different from one another at P=0.05. (Source: Subedi and Ma 2005)

Therateofnutrientuptake(Figure29)intheplantissimilartothatofdrymatter

accumulation(refertoFigures26and15).Itisimportant,however,thatnutrientuptake

beginsevenbeforetheplantemergesfromthesoil.Theamountsofnutrientstakenupearly

inthegrowingseasonaresmall,butthenutrientconcentrationinthesoilsurroundingthe

rootsofthesmallplantattheearlycriticalstagesmustbehigh.

Phosphorus

AlargeproportionoftheNandPtakenupbytheplantisremovedinthegrainatharvest

(Figure29).

Potassium

Bytheendofflowering,theplanthastakenup>90%ofitsKrequirement(Figure29).

TheplantcontinuestotakeupNuntilabout2weeksafterflowering,anditkeepstaking

upPfor4weeksafterflowering.UptakeofKiscompletedsoonaftersilking(Figure29).

MostoftheKtakenupisreturnedtothesoilintheleaves,stalksandotherplantresidues.

Repeatedremovalofplantmaterialthroughhay-makingorsilagecanleadtoKdeficiencyin

thesoil. 27






December 2014



Figure 29:

Nitrogen–Corn

% o

f to

tal u

pta

ke

100

80

60

40

20

0

Phosphorus–Corn

% o

f to

tal u

pta

ke

100

80

60

40

20

0

Potassium–Corn

% o

f to

tal u

pta

ke

100

80

60

40

20

0

Ve0 20 40 60 80 100 120

V6 V12 V18 R1 R2 R3 R4 R5 R6


Ve0 20 40 60 80 100 120

V6 V12 V18 R1 R2 R3 R4 R5 R6


Ve0 20 40 60 80 100 120

V6 V12 V18 R1 R2 R3 R4 R5 R6


Grain

Cob, shank, silks

Husks, lower ear shoots

Stalk, tassel

Leaf sheaths

Leaves

• N demand increases rapidly from 40 days after sowing until about 2 weeks after flowering.

• By the end of flowering, maize has taken up most of its K requirement.

• The uptake of N+P continues until near maturity

Uptake of nitrogen, phosphorus and potassium fertiliser applied at different stages of the life cycle of the maize plant. Day 0 is sowing day. (Modified from: Ritchie et al. 1992)




December 2014



4.3 Reproductive development

4.3.1 Stages

Tasselling–VT

Thetassel(Figure30)isthemalefloweringstructureofthemaizeplant.Figure31shows

tasseldevelopmentfromVTtopollenshed.

Theonlyfunctionofthetasselistoproduceenoughpollentofertilisetheovulesinthe

femaleflower(theear).Avigorousmaizetasselcanproduce2–5millionpollengrains.If

thereare1000silkspercob,thereare2000–5000pollengrainsproducedforeachsilk.

Alargevolumeofpollenisneededbecausethemaleandfemaleflowersarephysically

separatedandtherearemanyfloretsoneachplant.Alargevolumeofpollenensures

enoughpollenforeveryexposedsilk.

Normally,thetipofthetasselcanbeseenataboutthetimethatthetipoftheemergingear

becomesvisible.Thetasselemergesfromtheenclosingleavesbeforepollenshed(Figure

30),whichisusually1–2daysbeforesilksfirstappear. 28

Figure 30: Plant at the VT stage with the tassel fully developed. (Source: Ritchie et al. 1992)






December 2014



Figure 31: Tassel growth and development from VT through to pollen shed. (Source: Ritchie et al. 1992)

Flowering (pollen shed and silking)–R1

Therearetwopartstothepollinationprocess:

1. Viablepollenmustbeshedandlandonreceptivesilks.

2. Thepollenmustgerminateandformpollentubestoallowmalegametes(sexcells)

tofusewithfemalegametesinsidetheovule.

Pollen shed

Pollengrainsdevelopandmatureinanthersofthetassel,eachofwhichcontainsalarge

numberofpollengrains.Theanthersemergefromtheenclosingglumes,usuallyearlyto

mid-morningafterthedewhasdriedfromthetassel.Theantherssplitopenandshed

pollenintotheair.Atleast100pollengrains/cm².dayareneededtosuccessfullypollinatea

maizefield.

Pollengrainsarelightandcanbecarriedonthewind,butmostsettlewithin5–15mfrom

wheretheywerereleased.Onefull-sheddingtasselcanprovideenoughpollenforseveral

ears,ifthetiminganddistributionofpollenareright.

Pollenisshedforseveraldays(typically5–10days),withpeakproductiononaboutthe

thirdday.Pollenshedbeginsfromthemiddleofthecentralspikeofthetasselandends

withshedfromthetipsandbasesofthelowerbranches.

Pollenshedisnotacontinuousprocess.Itstopswhenthetasselistoowetortoodryand

beginsagainwhentemperatureandmoistureconditionsarefavourable,orwhenadditional

pollenhasmatured.Onatypical,clear,midsummerday,peaksheddingoccursbetween

9amand11am(EST).

Despitetheoverlapintimingofpollenshedandsilking,pollenofagivenplantrarelylands

onthesilksofthesameplant.Thisisduetoairmovement,leafplacementandthevertical

separationbetweenthetasselandtheear.Undernormalfieldconditions,upto97%ofthe

kernelsproducedbyaplantdevelopfrompollenshedbyotherplantsinthefield.




December 2014



Silking

Ordinarily,thefirstsilksproducedonaplantemergefromtheenclosinghusks1–3days

afterpollenshedhasbegun.Underfavourablegrowingconditions,allsilkswillemergeand

bereadyforpollinationwithin3–5days,whichisenoughtimeforallsilkstoreceivepollen

beforethetasselstopssheddingpollen.

Asisthecasewithotherplantparts,silkgrowthtakesplacemostlyatnight;studieshave

shownthatsilkscangrow5–8cminasinglenight.Thesilksfromnearthebaseofthe

earemergefirst,aftergrowingforseveraldays,andthosefromthetipappearlast.Silks

generallyappearoutsidethehusksattheendoftheearinthemorning,readytoreceive

pollenasitisshed.

Whenviablepollengrainsfallonmaizesilks,theyaretrappedbysmallhair-likeprojections

calledtrichomes(Figures32and33).

Figure 32: Pollen sticking to the trichomes on the silks. (Source: Strachan 2001)

Figure 33: Trichomes extending from the main stem of the silk. (Source: Strachan 2001)

Fertilisation and growth of the pollen tubes

Pollengrainscontainstarchasanenergysupply,andtheygerminatewithinafewminutes

oflandingonthetrichomes.Theyproduceapollentube,whichgrowsdownthesilk

channelandenterstheovary(Figure34).Thesepollentubesalwaysgrownearthesilk.This

isbecausethesilkssupplyallofthenecessarynutrientsandwaterforgrowthofthepollen

tubes.

Thepollentubegrowsthelengthofthesilkin12–28h.Thepollentuberupturesatthetip

toreleasenucleiintotheovule,fertilisingboththeegg,whichdevelopsintotheembryo,

andthepolarnuclei,whichdevelopintotheendospermofthenewkernel.




December 2014



Afterfertilisation,anabscissionlayerformsnearthekernelandthesilkdetaches,leaving

atiny‘silkscar’onthekernel.Silksthatarenotpollinatedcontinuetogrow,sometimes

reachingalengthof15cmormore.

Dependingonwateravailabilityandenvironmentalconditions,itmaytakefromjustafew

hoursto~1dayforpollentubestogrowallthewaytotheovules.Whenthemaizeplantis

undergreatermoisturestress,pollentubegrowthisslowerandthepotentialforsuccessful

fertilisationdecreases. 29

Figure 34: Pollen tubes growing along silk vascular tissue. (Photo: Antonio Perdomo, Pioneer Hi-Bred)

4.3.2 Factors affecting reproductive developmentStressduringpollinationcanhavesubstantialeffectsongrainyield.Akernelthatdoesnot

begindevelopingatthisstagecannotstartlater,andanearshootthatisnotwellformed

andfullypollinatedcanneverbecomeafull-sizedearatmaturity.Inotherwords,pollination

functionsasan‘on–off’switchforeventualgrainyield.

Althoughthepollinationprocessmayseemvulnerabletoweatherproblems,somefeatures

helptomakeitwork.Pollendoesnotshedwhenthehumidityishigh,sogenerally,itisnot

washedoffthetasselduringrain.Also,becausesilksurfacestendtobeabitsticky,pollen

isusuallynotwashedorblownoffafteritlandsonasilk.Moreover,pollensheddingusually

takesplaceinthemorning,beforethehightemperaturesanddryingwindsoftheafternoon.

Moisture stress

Themostcriticalperiodformoisturestressinmaizeis10–14daysbeforeandafter

flowering.

Theamountofwateravailableforsilkgrowthsubstantiallyinfluenceswhensilksemerge,

theirrateofgrowth,thedurationofthereceptivity,andtheirabilitytosupplywaterand

nutrientstosupportpollentubegrowthandfusionofthegametes(sexcells).






December 2014



Maizeplantsthataregrowingunderstressduringpollinationproduceearswithportions

ofthecobsthatarebarren(Figure35).InFigure35,thedevelopingearswereexposedto

pollenfor1daythencoveredtoexcludepollenagain;theearontheleftwasexposedfor

the10daysofpollenshed.Portionsofthecobsarebarrenbecausematureovuleswere

notproperlyfertilised.Theseunfertilisedovulesbegintodisintegrateanddisappearbefore

theearreachesphysiologicalmaturity.

Moisturestressatfloweringorduringgrainfillreducesthenumberofkernelsperplantand,

inturn,grainyield.Grainyieldisreduced2–3-foldmorewhenmoisturestresscoincides

withfloweringthanatothergrowthstages(Figure36).

Moisturestressatfullsilkingwillreduceyieldsby6–8%perday.Ifmoisturestressis

combinedwithnutrientstress,yieldscanbereducedby13%perday.

Figure 35:

ear weight

kernel count

120

100

80

60

40

20

01 2 3 4 5 6 7 8 9 10 11

weeks after emergence

per

cent

of

norm

al e

ar field is 50% silk on day 4

• The amount of kernels that develop depends on the amount of time the silks are exposed to pollen.

• At day 4, the field is at 50% silk.• The ear in the photo above was exposed for 10 days

The proportion of kernels that develop depends on the amount of time that silks are exposed to pollen. (Source: Strachan 2001)




December 2014



Figure 36:

% y

ield

dec

line

per

day

of

stre

ss 9

7

5

3

10 20 40 60 80 100 120 140

days after planting

silkingmaturity

Relationship between age of crop and percentage yield decrease due to 1 day of moisture stress. (Source: Shaw 1976).

Temperature

Maizeisafast-growingcropthatyieldsbestwithmoderatetemperaturesandaplentiful

supplyofwater.

Theidealdaytimetemperatureis26°–30°C,butwithfullirrigation,maizecantoleratehigh

temperatures.

Whentemperaturesreach≥38°C,itisdifficulttomaintainadequatewatermovement

throughtheplant,evenunderirrigation.

Night-timetemperatures>21°Ccanresultinwastefulrespirationandlowerdrymatter

accumulationintheplant(Figure37).

Figure 37:

dry

wei

ght

acc

umul

atio

n cool

hot

day night

photosynthesis (gain)respiration (loss)



day night day night

Plant growth involves accumulation of dry weight from photosynthesis during the day and loss of respiration at night. When night-time temperatures are too high, respiration loss is excessive (lower line). The result is similar on a very cloudy, warm day. (Source: Hoeft et al. 2000)




December 2014



ThedatainTable3showthathighnight-timetemperaturescanreduceyieldby40%.

Table 3: Effect of night-time temperature on grain yield

Treatment Average night-time temperature (°C)

Grain yield (t/ha)

Natural air 18.3 10.5

Cooled 16.6 10.17

Heated 29.4 6.28

Pollination

Hot,dryweatherismuchmorelikelytointerferewithpollinationthanwetweather.

Pollenmayloseviabilitywithinafewminutesifairtemperaturesarehigh(>40°C)andwater

stressispresent.Pollengrainscontain~80%waterwhenfirstshed.Thesepollengrainsdie

whenthewatercontentdecreasesto~40%.

Despitethis,alotofmaizeissuccessfullypollinatedunderhigh-temperatureconditions.If

soilmoistureisadequateandthemaizeplantcantranspirewaterrapidlyenoughtosupply

necessarywatertothepollen,thepollenremainsviablelongenoughtoshedproperlyand

completethefertilisationprocess.However,ifthewatersupplyisinadequate,pollenwilldie

prematurelyandnotcompletefertilisation.

Silk growth

Themostcommonproblemofhightemperatureistheslowgrowthofsilks,whichcan

resultinfailureofsilkstoemergeintimetoreceivepollen.Poorphotosyntheticactivitymay

contributetothisproblem.Silkscanalsodryrapidlyunderhot,dryconditionsandmaynot

containenoughmoisturetosupportpollengerminationandgrowthofthepollentubetothe

ovary.

Assimilate supply

Thefirstfewdaysafterfertilisationareacriticalperiodtoo.Ifproteinsandsugarsarein

shortsupply,kernelsneartheendoftheearoftenabort,meaningthattheyfailtodevelop

evenaftersuccessfulfertilisation.Lackofsugarsandproteinsmayresultfromlackofwater,

nutrientdeficiencies,reducedphotosynthesisduetoverycloudyweather,shadingfrom

veryhighplantpopulations,ordamagetoleavesfrominsectsordisease.Trialworkinthe

UnitedStatesfoundthat90%shadefor3daysdecreasedtheyieldofonehybridby25%,

and6daysofshadereducedtheyieldofthesamehybridby71%.

Competition from other plant parts

Duringflowering,eargrowthissusceptibletocompetitionfromotherplantparts.Theearis

competingforthelimitedsupplyofassimilatesfromphotosynthesis.Theresultcanbelow

grainnumberperearand,occasionally,barrenears. 30






December 2014



4.4 Kernel development

4.4.1 Stages

R2 (blister stage)

Afterfertilisation,theearcontinuestogrow.Forthefirstfewdays,littlevisiblechangetakes

placeinthefertilisedearshoot,exceptthatthesilkswiltandturnbrown.

Tendaysafterfertilisation,developingkernels(Figure38)appearaswateryblistersonthe

cob;thisistheblisterstageorR2(Figure39).Bythistime,thecobhasreacheditsfull

lengthanddiameter.

Withinthenext2weeks,thekernelsgrowveryrapidlyandthedevelopingembryotakes

shapewithinthem.Atthisstage,mostoftheplantsphysiologicalactivityisdirected

towardsfillingthekernels.Kerneldryweightincreaseslinearlyuntilneartheendofthe

grainfill.

Figure 38: Kernel attachment to the cob. (Source: Strachan 2001)

Figure 39: The R2 (blister) stage. (Source: Ritchie et al. 1992)




December 2014



R3 (milk stage)

Around20daysafterpollination,thekernelsareyellowontheoutsideandfilledwitha

milky,almostfluidsubstance,highinsugarsbutcontainingthebeginningsofstarch-and

protein-formingbodies.Thisisthe‘roastingear’,ormilkstage(R3)(Figure40).Ifsevere

stressoccursduringtheseearlyreproductivestages,thekernelsmaybeabortedfromthe

tipdowntolessentheloadontheplant.

Figure 40: The R3 (milk) stage. (Source: Ritchie et al. 1992)

R4 (dough stage)

Fromthebeginningofthedoughstage(3weeksaftersilking)(Figure41)untilabout5

weeksaftersilking,thecontentsofthekernelundergoamarkedchange.Sugarscontinue

topourintothekernelasbefore,buttheyarerapidlyconvertedtostarch,firstintheformof

thesticky,gummydextrins,andshortlyafterwardsintodrierstarch.Starchiscomposedof

sugarmoleculesjoinedtogetherinlongchainswiththehelpofstarch-formingenzymes.

Figure 41: The R4 (dough) stage. (Source: Ritchie et al. 1992)




December 2014



R5 (dent stage)

Thetoporcrownofthekernelisthefirstareawherehardened,drystarchisdeposited.

By40daysafterfertilisationatstageR5,ordent(Figure42),adefinitebandcanbeseen

acrossthekernel.Theband,alsoreferredtoasthemilkline(Figure43),isthelinebetween

themilkydepositsandthematuringdrystarch.

Theamountofdrymatterinthekernelisincreasing.Inthesoftdoughstage,about55%

ofthekernelsarestartingtodent,andintheharddoughstage>90%aredented.Bythe

endoftheseventhweekofkerneldevelopment,theembryohasnearlyreacheditsfullsize,

fillinghasbeguntoslow,andthekernelisapproachingmaturity. 31

Figure 42: The R5 (dent) stage. (Source: Ritchie et al. 1992)

Figure 43:

kernel tip 54321

The receding milk line. (Source: Colless 1992)

4.4.2 Maturity and drying

Stage R6 (physiological maturity)

Bytheendoftheeighthweekafterpollination,themaizekernelhasreachedmaximumdry

weight.

Atthetipofthekernelisalayeroftissue.Thistissueconductssugarandotherassimilates

intothekernel.Asthegrainmatures,thelayercollapses,stopsfunctioning,andturns






December 2014



black.Theblacklayerindicateswhenthekernelhasreachedphysiologicalmaturity(stage

R6)(Figure44).Anindividualearcanbeconsideredmaturewhen75%ofthekernelsinthe

centralpartofthecobhaveblacklayers.

Theperiodfrompollinationtophysiologicalmaturitytakesabout50–60days.

Thetimingofharvestmaturityoftheeardependsentirelyonmoisturelossinordertoreach

agrainmoisturelevelfavourableforharvesting.Weatherconditionsatthistimedetermine

therateofdry-down.

Figure 44: The R6 stage (physiological maturity). (Source: Ritchie et al. 1992)

Factors affecting kernel development

Approximately85%ofgrainyieldiscorrelatedwiththenumberofkernelsproducedper

hectare,withtheremaining15%correlatedwiththeweightofindividualkernels.

Conditionsduringkerneldevelopmentdeterminekernelsize,whereasconditionsinearlier

growthstagesmainlydeterminethenumberofearsandkernelsperear(Figure45).

Understandingstressduringkernelfillingcanhelpexplainwhycobshaveabortedkernels

orabnormalfillpatterns(Figures46and47).




December 2014



Figure 45:

gra

in h

arve

st w

t (g

ram

s/ea

r)

227

198

170

142

114

85

57

28

0

kernels per ear8007006005004003002001000

Grain yield per ear as a function of number of kernels per ear from the experiment in Figure 35. (Source: Strachan 2001)

Figure 46: Environmental stress has reduced the width and length of the cob on the right. (Photo: Kieran O’Keeffe)

Figure 47: Various stress factors can lead to missing kernels. (Source: Strachan 2001)




December 2014



Moisture stress

Thenumbersofearsandnumberofkernelspereararefixedsoonafterfertilisation.

However,moisturestress,especiallywhencoupledwithhightemperature,lackofnutrients,

diseaseorinsectattack,willreducekernelsizeandweight,andwilldeterminewhethertip

kernelswillfilleveniftheyarepollinated.

Incasesofextremestress,theplantdiesbeforethegrainhasreachedfullsize.Onthe

otherhand,exceptionallyfavourablemoistureconditionscanresultinbetterthanexpected

kernelfillandgiveahighergrainyield.

Whenmaizeplantsbecomemoisture-stressed,thelowerpartsoftheplantwiltandsuffer

proportionatelymoredamagethantheupperparts.

Withsomehybrids,moisturestressslowsthedevelopmentofthesilksmuchmorethan

thatofthetassel.Thisresultsinthepollenbeingspentbeforethesilksemerge,andlittle

ornograinformingonthecobs.Itisthereforeimportanttoselectearly-maturinghybridsin

drylandorlimited-irrigationsituations.

Figure48isanexampleoftheestimateddailywateruse.Thetasselling–doughperiodis

thetimeofpeakwateruseand,therefore,verysusceptibletomoisturestress.Withinthis

period,thesilking–blisterstageiscritical.Consequently,ifonlyonewateringcanbegiven,it

shouldbeappliedjustbeforetasselling.

Yieldisgenerallylostwhenmaizeisvisiblywiltedfor4consecutivedays.Figure49shows

theyieldlossduetowiltingatvariousstages.

Figure 48:

1.40

1.20

1.00

0.80

0.60

0.40

0.20

0.00

October November December January February March

8 leaf tasselsemerge

blisterdough

dent maturity

silking

Cro

p c

oef

ficie

nt

milk

Crop coefficient curve used to estimate maize daily water use from evapotranspiration data. Based on a mid-October crop sown at Gunnedah. For use with pan evaporation data, the coefficient should be multiplied by 0.8. (Source: Australian Maize)




December 2014



Figure 49:

yield with 4 days of vi

sible

wilting

0

20

40

60

80

10030 40 50 60 70 80 90

days after emergence

yiel

d lo

ss %

yield loss with no wilting

loss dueto wilting

tassellingblisterstage

doughstage

The maize crop coefficient can be estimated by walking through a crop on a sunny day in late morning or early afternoon. Make note of the percentage of shaded ground. Add 20% to the estimate and the result is the coefficient of the crop.For example, if 75% of the ground is shaded + 20%, then the crop coefficient is 95% or 0.95

silking

Yield loss due to wilting. (Source: Colless 1992)

Timing of the last irrigation

Thefinalirrigationmustbeappliedafterthegrainiswelldented(usuallymilkline2or3;see

Figure43)sothereisamplesoilmoistureforthecroptocompletelyfillthegrain.Ifthecrop

suffersmoisturestressduringthelast10–14daysbeforematurity,yieldisreducedby<1%

perday,butthisisstillasignificantlossifthestresspersistsforanumberofdays.32

4.4.3 References and further readingJBolanos,GOEdmeades(1996)Theimportanceoftheanthesis–silkingintervalinbreeding

fordroughttoleranceintropicalmaize.Field Crops Research 48,65–80.

RCakir(2004)Effectofwaterstressatdifferentdevelopmentstagesonvegetativeand

reproductivegrowthofcorn.Field Crops Research 89,pp.1–16.

JMColless(1992).Maizegrowing.AgfactP3.3.3,secondedition.NSWDepartmentof

Agriculture, Orange, NSW.

TFarrell,KO’Keeffe(2008)SummerCropProductionGuide2008. Part2:Grainssorghum,

maize.NSWDepartmentofPrimaryIndustries,Orange,NSW.

FRGrant,BSJackson,JRKiniry,GFArkin(1989)Waterdeficittimingeffectsonyield

componentsinmaize.Agronomy Journal 81,61–65.

PWHeisey,GOEdmeades(1999)Maizeproductionindrought-stressedenvironments:

technicaloptionsandresearchresourceallocation.‘WorldMaizeFactsandTrends

1997–1998.Part1.’CIMMYT,MexicoDF.

RHoeft,ENafziger,RJohnson,SAldrich(2000)Moderncornandsoybeanproduction:

Howthecornplantdevelops. Specialreportno.48,IowaStateUniversity,Ames,IA.

RHuang,DLGeorge,CJBirch(2006)Theagriculturalwatersupplychallenge—theneed

forimprovedwateruseefficiency.In‘MaizeAssociationofAustraliaConference

Proceedings2006’. MaizeAssociationofAustralia,Shepparton,Vic.






December 2014



MEJensen(1973)‘Consumptiveuseofwaterandirrigationwaterrequirements.’ American

SocietyofCivilEngineers,NewYork.

AKaiser,JColless,JLawson,CNicholls(Eds)(1997)‘Australianmaize.’ Kondinin Group,

Redlands,WA.

DMcCaffery,SBoyle(1997)Seedbedpreparationcrucialformaize.In‘Australianmaize’.

pp.51–60.EdsA.Kaiseret al.KondininGroup,Redlands,WA.

GSMcMaster,WWWilhelm,ABFrank(2005)Developmentalsequencesforsimulatingcrop

phenologyforwaterlimitingconditions.Australian Journal of Agricultural Research 56,

1277–1288.

RCMuchow(1989)Comparativeproductivityofmaize,sorghumandpearlmilletina

semi-aridtropicalenvironment.IIEffectsofwaterdeficits.Field Crops Research 20,

207–219.

RLNielsen(2006)Effectofplantspacingvariabilityonmaizeyield.In‘Watertogold.

Proceedingsof6thTriennialConferenceoftheMaizeAssociationofAustralia’.Griffith,

NSW,Australia.MaizeAssociationofAustralia,Shepparton,Vic.

PioneerHi-BredAustralia(2007)Growingmaizeforprofit.Maizeworkshopnotes. Pioneer

Hi-Bred.

SRitchie,JHanway,GBenson(1992)Howacornplantdevelops. Special report no. 48,

IowaStateUniversity,Ames,IA.

RHShaw(1976)Wateruseandrequirementsofmaize—areview.Agrometeorology of the

Maize Crop,WorldMeteorologicalOrganisation481,119–134.

SDStrachan(2001)Cropinsights.Corngrainyieldinrelationtostressduringear

development.GRDCIrrigationUpdate,Tocumwal,2001,pp31–38.

KDSubedi,BLMa(2005)Nitrogenuptakeandpartitioninginstay-greenandleafymaize

hybrids.Crop Science 45,740–747.

JWhite(2003)PotassiumnutritioninAustralianhighyieldingmaizeproductionsystems—a

review.In‘ProceedingsoftheFifthAustralianMaizeConference’.Toowoomba


Section 5 MAIZE - Nutrition and fertiliser


December 2014



SECTION5

Nutrition and fertiliser

Maizeyieldandqualityarebothaffectedbycropnutrition.Maizeisresponsivetofertiliser,

especiallynitrogen(N),phosphorus(P)andpotassium(K).High-yieldingmaizecropsrequire

largequantitiesofsoilnutrients.Inahealthymaizecrop,alloftheupperleavesandmostof

thelowerleavesremaingreenuntilthecropisnearlymature(Figure1).Toensureoptimal

useoffertilisers,asoiltestshouldbeconductedpriortoplanting.

MaizegrowsbestinsoilswithapHrangeof5.6–7.5.IfthepHis<5,limeshouldbe

appliedandincorporatedintothesoil3–6monthsbeforeplanting.Analternativeistoapply

dolomite,whichhasaneutralisingvaluesimilartolimebutappliesmagnesium(Mg),which

maycausecationimbalanceifusedincorrectly.1Consultyouragronomistorsoilnutrition

experttogetrecommendationsforyoursituation.

Ofalltheessentialnutrientsderivedfromthesoil,N,PandK(theprimarynutrients)

represent83%ofthetotalabsorbed.Calcium(Ca),Mgandsulfur(S)arethesecondary

nutrientsandrepresentanother16%,leavingonly1%asmicronutrients.

Theamountsofmicronutrients—boron(B),chlorine(Cl),copper(Cu),iron(Fe),manganese

(Mn),molybdenum(Mo)andzinc(Zn)—requiredareverysmallbutthesearestillimportant

toachievingmaximumyieldandshouldonlybeappliedwhennecessary.


i More information

RLines-Kelly(2004)

Whichlimingmaterialis

better?NSW DPI.

G MacKinnon et al. Soil

fertilitymanagement

in low-rainfall farming

systemsofcentral

westernNSW.NSWDPI.

MakingBetterFertiliser

DecisionsforCropping

SystemsinAustralia.




http://www.dpi.nsw.gov.au/agriculture/resources/soils/acidity/publications/best-lime



http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0020/167015/soil-fertility-brochure.pdf





http://www.bfdc.com.au





December 2014



Figure 1: In a healthy maize crop, all of the upper leaves and most of the lower leaves remain green until the crop is nearly mature.

Somesoilnutrientsaremorelikelytohavedeficiencyproblemsthanothers,forexample

zincdeficiencyonhighpHsoils.Ofthesecondarynutrients,MgandSarethemostlikely

tobeaproblem,andthenusuallyonlyonlowpHand/orsandysoils,andMgmayevenbe

toohigh.

Onceayieldgoalhasbeenset,afertiliserprogramcanbeworkedouttoprovidethe

necessarynutrients.Theyieldgoalshouldbesetsothatitfallsintheupperrangesofwhat

isbelievedattainable,andthentheamountsoffertiliserneededtoreachthatgoalshould

becalculated.Figure2showstheamountsofN,P,K,SandMgremovedbyamaizecrop

dependingonyieldandonwhetherthecropisforgrainaloneorforsilage.Acropof5.5t

grain/ha(40tgreenchop/ha)isayieldthatcouldbeobtainedunderreasonabledryland

conditions.Acropof11tofgrain/ha(65tgreencrop/ha)isachievableunderirrigated

croppingconditions.

TheAustralianrecordforamaizecropis21.5tgrain/haandthegeneticpotentialis

believedtobe~36t/ha.

Healthyleavesshinewitharich,darkgreencolourwhenadequatelyfed.

Phosphateshortagemarksleaveswithreddishpurple,particularlyonyoungplants.

Potassiumdeficiencyappearsasafiringordryingalong thetipsandedgesoflowestleaves.

Nitrogendeficiencysignisyellowingthatstartsatthetip andmovesalongmiddleofleaf.

Magnesiumdeficiencycauseswhitishstripsalongtheveinsandoftenapurplishcolourontheundersideoflowerleaves.

Droughtcausesthecorntohaveagreyishgreencolour andtheleavesrollupnearlytothesizeofapencil.

Disease,Helminthosporiumblight,startsinsmallspots andgraduallyspreadsacrossleaf.

Chemicalsmaysometimesburntips,edgesofleaves andatothercontacts.Tissuedies,leafbecomeswhitecap.

i More information

Saline,sodic,magnesic

oralloftheabove?Back

PaddockCompany.


http://www.backpaddock.com.au/news/saline-sodic-magnesic-or-all-of-the-above/





December 2014



Kilograms per hectare

Maize: Grain and Silage N P K S Mg

5.5t/hagrain Grain 121 19 24 9 11

40t/hagreenchop Stover 44 7 97 11 20

(12.8t dm/ha) Total 165 26 121 20 31

7t/hagrain Grain 136 24 30 11 13


(16t dm/ha) Total 190 34 150 24 38

8.5t/hagrain Grain 151 28 36 13 15


(18.5t dm/ha) Total 215 40 179 28 45

10t/hagrain Grain 176 32 41 15 17


(20.8t dm/ha) Total 240 46 208 32 52

11t/hagrain Grain 190 35 45 16 18


(22.4t dm/ha) Total 270 50 225 34 56

Figure 2: Plant nutrients taken up by the maize crop according to yield goals.

WhereasFigure2showsthetotalquantityofmajornutrientsrequired,Figure3indicates

theperiodsandratesofuptakeforN,PandK.Byusingthetwotablesinconjunction,the

fertiliserquantitiesrequiredbythemaizecropateachstageofgrowthcanbecalculated.2

Figure 3:

Per

cent

age

of

tota

l NP

K u

pta

ke

100

90

80

70

60

50

40

30

20

10

Weeks

Percentag

e of to

tal dry w

eight

100

90

80

70

60

50

40

30

20

10

0 0

dry

mas

s

K N P

2 4 6 8 10 12 14 16

Timing and rates of uptake for nitrogen, phosphorus and potassium. (Source: Pioneer)

5.1 Soil fertility

Thefertilityofasoilisacombinationofitsphysicalcharacteristics(structure,texture,

stability,density,organicmattercontent)anditsnutrientstatus(amountofN,P,Kand

otheressentialnutrientsthatarereadilyavailabletothecrop).Togrowaprofitablecrop,we

shouldaimforthebestcombinationofphysicalandchemicalcharacteristics.

2 Growthpotential.Corngrower’sworkshop.PioneerHi-BredAustralia.http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Corn_Workshop_Book.pdf

i More information

Nutrition, irrigation and

weedsformaize.DAFF

Qld.


guide 2014. NSW DPI

Management Guide.

Nutrientsourcesfor

crops.IncitecPivot

Fertilisers.

Growthpotential. Corn

grower’sworkshop.

Pioneer Hi-Bred

Australia.

ENTEC—Benefitsin

maize. Incitec Pivot

fertilisers.

Historicbaseforfertiliser

decisions.GRDCGround

CoverIssue97.










http://www.incitecpivotfertilisers.com.au/News/Latest News/Cropping/Nutrient sources for crops







http://entecfertilisers.com.au/ENTEC/ENTEC Benefits/ENTEC in Maize



http://grdc.com.au/Media-Centre/Ground-Cover-Supplements/Ground-Cover-issue-97-MarApr-2012-Supplement-More-profit-from-nutrition/Historic-base-for-better-fertiliser-decisions





December 2014



Theculturalpracticesemployedingrowingacrop(e.g.no-tillversusconventionalfarming)

willhavethegreatesteffectonasoil’sphysicalstructure.Thegreaterthevolumeofsoilthe

rootsystemcanexplore,thegreatertheyieldpotential.

Growerswithhardsettingsoilsshouldimplementpracticessuchasdeeprippingtobreak

hardpansandpermanentbedsorno-tilltoimprovemoistureinfiltrationtotheroot-zoneof

thecrop.Inter-rowcultivationcanalsobeusedtoimprovecropgrowthandwaterinfiltration

aswellastocontrolweeds.

Apartfromsomecarbon,hydrogenandoxygenderivedfromtheair,thesoilisthesole

supplieroftheplant’snutrientandwaterrequirements(exceptwherefoliarfertilisationis

usedforaspecificpurpose).

Higherratesorfertilisercanbeprofitablyusedwithsuperiormanagementthanwithaverage

management(Figure4).InFigure4,withaveragemanagement,rateAisoptimal,andwith

superiormanagement,rateBisoptimal(fromStrizel1963).Thesoilholdsplantnutrientsin

manyforms.Somearereadilyavailabletotheplant,whereasothershavetobechanged

fromaninorganictoanorganicformthattheplantcanuse.Notethatalthoughcrop

nutrientrequirementsareminimalinthefirst6weeksofgrowth,themajorityoffertiliser

shouldbeappliedatorpriortoplanting.

Figure 4:

O A BFertiliser rate

Yie

ld in

crea

se o

r va

lue

of

yiel

d in

crea

se

Averagemanagement

Fertilisercost

Superior management

Effect of superior management on fertiliser cost returns. (Source: Pioneer)

Differenttypesofsoilholddifferentamountsofnutrientsandwaterfortheplanttouse.

Sandysoilsareusuallylowinfertility(loworganicmatterandleachreadily)sowillrequire

thefertiliserandwatertobeappliedinsuchamannerthatitisutilisedwhilereducingloss.

Somestrategiesrelyonsplitapplicationsofnutrientsthroughthegrowingseasonorthe

useoffoliarfertilisersandneedsmalldosesoffertiliserandwateroften(thisisnotalways

practicable).

Claysoils,ontheotherhand,areinherentlymorefertileandholdmorewaterbecauseof

thehigherleveloforganicmatterintheprofileandgreatercationexchangecapacity(a

resultoftheirclaymineralogycontent).However,tie-upofsomenutrientscanbeanissue.

i More information

Soilphosphorus

availability.IncitecPivot

Fertilisers.

MJBellet al.(2008)Fate

of potassiumfertilisers

appliedtoclaysoils

under rainfed grain

cropping insouth-east

Queensland,Australia.

Australian Journal of Soil

Research 47.

GSchwenkeet al.

Nitrogenvolatilisation

losses—howmuchN

islostwhenappliedin

differentformulationsat

differenttimes.NSWDPI.


http://www.nutrientadvantage.com.au/Latest News/Latest News/Soil Phosphorus Availability



http://www.publish.csiro.au/paper/SR08088.htm








http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0004/431275/Nitrogen-volatilisation.pdf








December 2014



Notallsoilshavenutrientsinaformavailabletotheplant—somesoilshaveahighfixing

capacity(e.g.PinhighlycalcareoussoilsorhighpHsoils).

Anotherinfluenceontheavailabilityofnutrientsisthesoil’spH.Figure5showsthechanges

inplantnutrientavailabilitywithchangesinsoilpH.ThewidthofthehorizontalbarinFigure

5indicatestherelativeavailabilityofeachnutrient.OptimumpHformaizeis6.0–7.0.Lime

willmakesoilsmorealkalineandincreasetheavailabilityofsomenutrientswhenappliedto

acidsoils. 3

Figure 5:

pH4.0 5.0 6.0 7.0 8.0 9.0

Available nutrients in relation to pH.

Nitrogen

Phosphorus

Potassium

Sulfur

Calcium

Magnesium

Iron

Maganese

Boron

Copper And Zinc

Molybdenum

Variability of plant nutrients with soil pH. (Source: Pioneer)

5.2 Soil testing

Maizeproducesalotofdrymatter;therefore,ituseslargeamountsofnutrients,which

manyAustraliansoilsarenotcapableofsupplyingwithouttheadditionoffertilisers.Soils

shouldberegularlytestedsothatyouareawareofthenutrientstatus,bothmacro-and

micro-nutrients,pHandorganicmatter.

Whenyouhaveanalysedthesoiltestresults,youcanplanafertiliserprogrambasedon

availablenutrientsand,mostimportantly,yourbudgetorexpectedyield.Ifgrowingmaize

forsilage,aslightlydifferentfertiliserprogramisneededthanforgrain.

Growerswillneedtoadjustreplacementratesbasedonremovalofbothgrainandstover.

Thisisasignificantlycostlyfertiliserprogram.


i More information

CGuppy et al.(2012)

Interpretingsoiltestsin

thelightofP,KandS

research.GRDCUpdate

Papers.

MBell,CGuppy(2014)

Interpretingsoiltest

resultsforthenorthern

region. GRDC Ground

CoverIssue108.




http://grdc.com.au/Research-and-Development/GRDC-Update-Papers/2012/04/Interpreting-soil-tests-in-the-light-of-P-K-and-S-research





http://grdc.com.au/Media-Centre/Ground-Cover-Supplements/GCS108/Interpreting-soil-test-results-for-the-northern-region







December 2014



5.3 Key nutrients

Insufficientsupplyofnutrientsleadstodeficiencysymptoms(Figure6).Maizetakesthe

largemajorityofitsKbysilkingbutrequiresasupplyofNandPbeyondgrainfill(Figure7).

Theaccumulationofwater,N,PandKisrapidintheearlystagesofgrowthbeyondthe

4–5-weekperiod.

Figure 6: Nutrient deficiency in maize. (Source: Pacific Seeds)




December 2014



Figure 7:

Maturity

17 weeks

16 weeks

15 weeks

14 weeks

13 weeks

12 weeks

11 weeks

10 weeks

Silking

Tasseling

7 weeks

6 weeks

5 weeks

4 weeks

3 weeks

2 weeks

1 week

Emergence

% N less

than 1 less

than 1less

than 1less

than 1

2

4

6

10

12

16

15

9

11

13

15

11

10

14

11

7

2

less than 1less

than 1less

than 1

% P less

than 1

1

2

5

8

7

4

16

20

21

16

2

1

less than 1less

than 1less

than 1

% K

-K

-K

-K

-K

--

--

1

5

8

12

11

10

7

8

11

12

9

3

1

less than 1less

than 1

% Water

less than 1

1

2

3

5

6

5

4

2

1

less than 1


Weekly nutrient requirements of maize. (Source: Incitec Pivot Ltd)

Fertiliserapplicationandtimingisextremelyimportant,withmaizebeinganaggressiveuser

ofnutrients,particularlyintheperiodleadinguptotasselling.Nutrientsmustbeavailableto

theplantwhenmostneeded.

BecauseofthehighlevelsofNrequired,Nfertiliserisusuallyappliedpre-plantinginthe

formofureaoranhydrousammoniaoratplantingifapplyingbetweentherows.Most

maizegrowerssplitapplicationofN,with~60–70%appliedpre-plantingandtheremainder

appliedeitherwater-runorside-dressedpriortotasselling.

Theothernutrientsareusuallyappliedpre-plantingoratplantingintheformofstarter

fertiliser.OnlyminorratesofKcanbeappliedintheseedtrenchatsowing;itisbetter

incorporatedintosoilpre-sowingtoprovidesufficientrates.

Placementoffertiliserisalsoimportantbecausetheemergingmaizeseedlingcantolerate

onlysmallamountsofN(5kg/ha)andP(10kg/ha)indirectcontact.Atthesametime,

emergingseedlingsneedaccesstopop-upfertiliser,togivethemagoodstart.




December 2014



Undercool,wetconditionsinsoilsthatarehighinpH,uptakeofsomenutrientscanbe

inhibitedandfoliarspraysmayberequiredtocorrecttheimbalance.Themainnutrients

affectedareZn,B,Fe,MnandCu(Figure8).4

Figure 8: Severe zinc deficiency in stunted plants. (Source: Pacific Seeds)

5.4 Animal manure

Manurecontainsvaluablenutrientsandorganicmatter.Thecompositionwillvary

dependingontheanimalandthefeedingregime.Micronutrientdeficienciesareseldom

foundonfieldsthatregularlyreceiveapplicationsofmanure.

Thenutrientscontainedinmanurearenotasefficientinstimulatingplantgrowthintheshort

termaschemicalfertilisers,butthereisaresidualeffectlastingupto4years.Thisisdueto

theslowreleaseofthenutrients.

Aswellashavingvalueintermsofnutrients,manurealsoactsasasoilimprover.Organic

matterimprovessoilstructure,helpsrootpenetrationandreducesthedegreeofsoil

compaction,allowingsoilstoholdmoreavailablewater.

DatafromaDalbyfeedlotshowedthatthemanurecontained2.17%N,1.28%Pand

2.61%K.Therefore,1tmanure(drymatter)wouldcontain21.7kgN;12.8kgPand

26.1kgK.However,onlyapercentageofthisisavailableinthefirstyear(possibly35%

oftheN,60%ofthePand90%oftheK),therestbecomingavailableinsubsequent

years.Variationsinsoiltypes,climaticconditionsandmanureusedwillgreatlyaffectthe

immediateavailabilityofthesenutrients.

BecauseNisacriticalnutrientforproducingmaximumyields,itisthereforerecommended

thattheamountofNfrommanureisnotcalculatedinthefirstgrowingyearofapplication.







December 2014



Whenconsideringusingmanure,haveananalysisdonesothatavaluecanbeputonthe

nutrientsitcontains.Itcanbemoredifficulttoputavalueonthesoil-improvingqualitiesof

manure.Eachsituationmustbetakenonitsownmeritsbuttheuseofmanurehasmany

andlastingbenefits.

Thetheoryofmaintenancefertilisationhasmuchmerit.Thesoilcanbeconsidereda

nutrientbank.Thehealthieritis,thehealthierthecropwillbeandthehighertheyields.

Thelikelihoodofaresponsetofertiliserisreducedbyanyfactorthatreducescropgrowth.

Yieldincreasesfromtheuseoffertilisersdependprimarilyon:

• thepotentialyield

• thelevelsofsoilnutrient

• soilmoistureatplanting

• theabilityoftheplanttotakeupnutrientsandtheavailabilityofplantnutrientsandsoil

moisturethroughoutthegrowthofthecrop

Considerationshouldbegiventocroprotationsthatinfluence,amongstotherfactors,the

amountofavailablesoilNforsucceedingcrops.SoilNismoreeffectiveforcropgrowth

thanisfertiliserN.NitrogenandKwillgenerallybethemostexpensivefertiliserinputsinthe

production of a maize crop.

Justasgoodmanagementiskeytoeconomiccropproduction,goodmanagementiskey

toeconomicfertiliserusage.5

5.5 Crop removal rates

ThequantityofNrequiredtogrowthecropisabout1.6timesthequantitythatwillbe

removedinthegrain.OthercropremovalratesarelistedinTable1.

Table 1: Nitrogen, phosphorous and potassium removal (kg/ha) by maize 6

Source:PacificSeedsYearbook2006/2007

Yield potential (t/ha):

Dryland IrrigationGrain Silage Grain Silage

Low Mid High Low Mid High Low Mid High Low Mid High 2.5 5 7.5 22 37 52 10 12.5 15 65 75 86

Nitrogen 40 80 120 68 136 204 160 200 240 272 340 408

Phosphorus 9 17 25 13 26 36 32 39 46 46 55 65

Potassium 11 22 32 65 112 157 41 51 60 207 245 284

5.6 Nitrogen

Nitrogenisbyfarthemostimportantnutrientforproducinghigh-yieldingcrops,butthe

needforotherelementsshouldnotbeforgotten.Ifasoilisdeficientinevenaminor

nutrient,highlevelsofNwillnotovercomethisdeficiency.



i More information

JLaycock(2011)Getting

nutritionrightin2011

afterabigyearin 2010.

GRDCUpdatePaper.

i More information

D Plénet, G Lemaire

(1999)Relationships

betweendynamicsof

nitrogenuptakeanddry

matter accumulation

inmaizecrops.

Determination of critical

N concentration. Plant

and Soil 216.






http://grdc.com.au/Research-and-Development/GRDC-Update-Papers/2011/04/Getting-nutrition-right-in-2011-after-a-big-year-in-2010




http://link.springer.com/article/10.1023/A:1004783431055











December 2014



BecauseNisthemostimportantnutrient,itsgoodmanagementisessential.Notonly

isthereaneedtoapplyenoughtofeedthecrop,italsoneedstobeavailableatcrucial

growthstages.

AppliedNcanbelostbeforetheplantcanuseit,byleaching,denitrification(waterlogging

orananaerobicenvironment)andimmobilisationbymicro-organisms.Nitrogenisan

essentialcomponentoforganiccompounds,protein,nucleicacidsandchlorophyll.If

removingthewholecropforsilage,youwillremove~75%moreNthanforgrainproduction. 7

RatesofappliedNgreatlydependontheyieldpotentialofthesoilsituation.

Adeepsoil-NtestcanprovideusefulinformationonavailableNforthecrop.TheNfertiliser

neededmaythenbepre-appliedand/orappliedatplanting,withtopdressingorside-

dressingtofillthetotalrequirements.

Post-emergenceapplicationsareusefulforirrigatedcropsorwhereheavyrainfallsafter

emergence.Ifthetotalamountoffertilisertobeappliedisside-dressedandapplicationis

delayedbeyondthefirst4weeksaftersowing,someyieldpotentialmaybelost(referto

Figures3and7).

Nitrogenisverymobileinthesoilandlossesthroughleachingcanbelarge.Denitrification

lossescanalsobesubstantialinwetsoils.ThetechniquesofsplitNapplicationand/or

water-runNcanbeusedtoadvantageundertheseconditions.

TwootherpointsneedtobeconsideredwhendeterminingNapplicationrates.First,the

efficiencyofuptakeoffertiliserNisoftenonly~50%.Second,organic(soil)Nis~15–20%

moreeffectivethanappliedfertiliserNforcropgrowth.Thislatterpointhasimportant

managementimplicationsforcroprotationsandresidualNinthesoil.

Agraincropof11t/ha(greenchopof70t/ha)willtakeuponly35%or95kgofitstotalN

requirementduringthefirst6weeksafteremergence.Thenext4weeks(priortoandduring

silking)willsee53%ofthetotalNrequirements(145kg)takenup.

WhencalculatinganNbudgetformaize,anefficiencyof~50%shouldbeusedforpre-

plantapplicationofinorganicNfertilisers,andahigherefficiencycanbeusedinsplit

applications.Discusswithyouragronomist.

Uptakepeaksat4kgN/ha/day,placinghugedemandsonfertiliseravailabilityandgrower

management.

Nitrogendeficiencyshowsinseveralways.WhenyoungmaizeisshortofN,thewhole

plantispaleyellowishgreen,small,andhasspindlystalks.Phosphorusdeficiencycanalso

causeplantstopurplewithstresspigment.

Later,beginningwiththebottomleaves,thetypicalV-shapedyellowingfromthetipsofthe

leavesshows.


i More information

MAAlleyet al. Nitrogen

andphosphorus

fertilization of corn.

Publicationsand

EducationalResources.

VirginiaCooperative

Extension.

DBBeegle,PTDurst.

Nitrogen fertilization

ofcorn.Agronomy

Facts12.PennState

Extension.

i More information

GSchwenkeet al.(2012)


losses:howmuchN

islostwhenappliedin


differenttimes.GRDC

UpdatePapers.

i More information

ENTEC—Benefitsin

maize. Incitec Pivot

fertilisers.

CDowling(2014)

Measuringnitrogenisfirst

steptoliftingefficiency.

GRDC Ground Cover

Issue112.

TDixon(2014)

Denitrification:thelatest

chapterintheNstory.

GRDC Ground Cover

Issue108.




http://pubs.ext.vt.edu/424/424-027/424-027.html







http://extension.psu.edu/plants/crops/grains/corn/nutrition/nitrogen-fertilization-of-corn





http://www.grdc.com.au/GRDC-UpdatePaper-SchwenkeEtAl2012-NitrogenVolatisation










http://grdc.com.au/Media-Centre/Ground-Cover/GC112/Measuring-nitrogen-is-first-step-to-lifting-efficiency





http://grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-108-Jan-Feb-2014/Denitrification-the-latest-chapter-in-the-N-story







December 2014



ThegreatertheNdeficiency,thegreaterthenumberofbottomleavesaffected.Smallcobs,

oftenwithbaretips,resultwhenNdeficienciesoccurduringsilkingandgrainfill.8

DepartmentofAgriculture,FisheriesandForestry(DAFF)Queenslandhasproducedarule

ofthumbforNapplicationindifferentregionsofthestate(Table2).

Table 2: Nitrogen application rates for dryland and irrigated maize in Queensland (kg/ha)

Area Dryland IrrigatedAthertonTablelands 0–80 –

Wettropicalcoast 130–180 –


DarlingDownsA 0–180 150–300

Moreton – 100–200

SouthBurnett 0-50 80–200

A Maximumrateforgrowersaimingfora7t/hadrylandcropor10t/hairrigatedcropfromgroundthathasbeencultivatedfor>25yearsandhasahistoryofsummercrops(suchassorghum,maize,millet,sunflower,cotton)orhasbeendouble-croppedwithwintercereals

SymptomsofNdeficiencyinclude:

• lightgreenoryellowishleaves,oftenwithaV-shapedyellowareaattipsofleaves

• prematuredryingalongthemidribandleaftips

• stuntedandslow-floweringplants

• shortandoftenpoorlyfilledears 9

5.7 Phosphorus

Phosphorusisanessentialelementinthedevelopmentandgrowthofthemaizeplant.Itis

alsoimportantinthetransferofenergywithintheplant.

Phosphorusisquiteimmobileinthesoil,soitisimportanttoplaceitclosebytheplant

line(5cmtothesideand5cmbelowtheseed)sothattheyoungplantrootshaveready

access.Undercoolandwetconditionsearlyintheseason,coupledwithhigh-pHsoils,

youngmaizeplantsoftencannotaccessenoughPuntilconditionsimprove.10This

immobilityalsomeansthatPcanbesuccessfullybankedinclaysoilssoremainingPmay

beavailableforsubsequentcrops.

TheDAFFguidelinesforPapplicationarepresentedinTable3.




i More information

Soilphosphorus

availability.IncitecPivot

Fertilisers.

M Bell et al.(2014)

Changingnutrient

managementstrategies

inresponsetodeclining

backgroundfertility.

GRDCUpdatePapers.

JLaycock(2014)

Economicsand

management of P

nutrition and multiple

nutrient decline. GRDC

UpdatePapers.











http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2014/03/Changing-nutrient-management-strategies-in-response-to-declining-background-fertility






http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2014/02/Economics-and-management-of-P-nutrition-and-multiple-nutrient-decline








December 2014



Table 3: Phosphorus application rates for dryland and irrigated maize in Queensland (kg/ha)

Area Dryland IrrigatedAthertonTablelands 0–35 –

Wettropicalcoast 0–35


DarlingDowns 9–15 0–15

Moreton – 0–15


SymptomsofPdeficiencyinclude:

• purplishcolouredleaves

• plantswithstuntedgrowth

• delayedflowering

• poorlydevelopedrootsystems

• reducedkernelsizeandnumber11

SoilanalysisresultsareusefulwhendevelopingaP-fertiliserprogram.Insomesoils,Pcan

reactwithothersoilcomponentsandbecomeunavailabletoplants.

Typically,recoveryisseldommorethan15–20%ofPapplied,evenundergoodconditions.

Phosphorusisvitalinearlyrootandseedlingdevelopment.

Fornormalgrowth,youngplantsneedahigherpercentageofPintheirtissuesthanthey

willlaterintheseason.Inaddition,Pisnotmobile(theoppositeofN)anddoesnotleach

outofsoilswithclaycontent.ThisallowsallofthePtobeappliedpriortooratplantingso

thattherootsmayhaveaccesstothefertiliser.

UptakeofPinplantscanberestrictedbypoorrootestablishment(e.g.compaction,

plantingslotsmearing)andcoldwetconditions,whichmayoccurwithearlyplantingsand

canresultinpoorrootvigour.Starterfertiliserwillhelpinthesesituations.

IfPdeficiencyisgoingtooccur,itwillappearbeforetheplantsare65cmtall.Itis

characterisedbyslow,stuntedgrowth,plantsthatareverydarkgreenwithreddishpurple

leaftipsandmargins,andstemsthatcanshowapurplecoloration.Astheplantdevelops,

plantmaturitywillbedelayed,rootsystemswillbelimitedandsilkswillemergeslowly.

Agraincropof11t/ha(70t/haofgreenchop)takesupabout30%or15kgofitsP

requirementsduringthefirst55days.Peakuptakeof0.75kg/ha.dayoccursduring7–10

weeksafteremergence,withtotaluptakebeing~50kg.12Thiscausesanetlossfrommost

P-fertiliserregimesinthenorthernregion;ifgrowersarelookingatreplacementratesforP,

orforPbanking,thenPapplicationratesneedtobeincreased.



i More information

GRDC(2012)Phosphorus

management. GRDC

CropNutritionFactSheet.

M Bell et al. Improving

phosphorusfertiliser

managementonsouthern

Queenslandgrainfarms.

SouthernQueensland

FarmingSystemsProject.

DEEDIQld.

i More information

GRDC(2009)Mycorrhizae

andtheirinfluenceonP

nutrition.GRDCUpdate

Papers.

D Plénet et al.(2000)

Growthanalysisof

maizefieldcropsunder

phosphorusdeficiency.

Plant and Soil 223.

MAAlleyet al. Nitrogen

andphosphorus

fertilization of corn.

Publicationsand

EducationalResources.

VirginiaCooperative

Extension.

A Mollier, SPellerin(1999)

Maizerootsystemgrowth

anddevelopmentas

influencedbyphosphorus

deficiency.Journal of

Experimental Botany 50.

JZhuet al.(2005)Topsoil

foragingandphosphorus

acquisitionefficiency

inmaize(Zea mays).

Functional Plant Biology

32.






http://www.grdc.com.au/GRDC-FS-PhosphorusManagement



http://www.daff.qld.gov.au/__data/assets/pdf_file/0006/49821/SQFS-Phosphorus-Fertiliser-Mgmt-Report.pdf







http://grdc.com.au/Research-and-Development/GRDC-Update-Papers/2009/09/MYCORRHIZAE-AND-THEIR-INFLUENCE-ON-P-NUTRITION




http://link.springer.com/article/10.1023%2FA%3A1004877111238#page-1












http://jxb.oxfordjournals.org/content/50/333/487






http://plantscience.psu.edu/research/labs/roots/publications/pdfs/FP05005.pdf








December 2014



5.8 Sulfur

Sulfurisaconstituentofaminoacids,vitaminsandenzymes.Traditionally,mostAustralian

soilshavebeenthoughttohaveacceptablelevelsofS.However,ongoingresearchhas

shownthatnotonlyarelevelslowerinsomeareasofnorthernNewSouthWalesand

theDarlingDownswithalongcroppinghistory,butalsothatthedepthofSinthesoil

reservescanaffectavailability.Responsesoccurinsoilsthatarelowinorganicmatterand

particularlyundercoolandwetconditionsearlyintheplant’slife.13

SomesoilsontheDarlingDownsandLiverpoolPlains(intensivelyfarmedfor>20years)

mayshowresponsestoS.Usually,8–10kg/haofSisadequate.Gypsumat200–400

kg/haevery3yearscanbethemosteconomicalformofSapplication;however,itisnot

immediatelyavailableandthesolubilityratewilldependonthequalityofthegypsum.

BecauseofthemobilityofS,itisimportanttoknowwhereitliesintheprofile.Ifthegypsum

lineisbelow60cm,itsSisunlikelytobetoodeeptobeavailabletothecropintheearly

stagesofgrowth.

SymptomsofSdeficiencyinclude:

• palegreenoryellowyoungplantswithonlylimitedstunting

• palegreen-yellowupperleavesonolderplants,withthelowerleavesremaininggreen

(theoppositeofNdeficiency)14

Sulfuroriginatesfromorganicmatterandisnormallyverymobileinthesoil.Typical

deficiencysymptomsofinterveinalchlorosisandstuntingareusuallymostsevereinthe

seedlingstage.UseofastarterfertilisercontainingSshouldcorrectanyproblems. 15

5.9 Potassium

Potassiumisimportantinthemaizeplantforthecirculationofsugars,starchformation,

Nuptake,photosynthesis,enzymeactivation,lodgingresistance,diseaseresistanceand

grainfill.

SoiltestsmayshowgoodreservesofKbutnotalwaysinaformaccessibletotheplant.

Potassium,likeP,isusuallyappliedpre-plantingoratplantinginaneasilyaccessibleband.

Potassiumistheelementthatistakenupthequickestbyagrowingmaizeplant(80%by

tasselling).

Potassiumisoftenoverlookedbysilagegrowers,andhayproducers,withalotofK

containedinthestoveroftheplant.Amaizegraincropof10t/hauses~39kgK,butthe

samecrop,iftakenoffforsilage,willdepletethesoilof183kgK. 16Inareaswithalong





i More information

GSchwenkeet al.


losses—howmuchN

islostwhenappliedin


differenttimes. NSW DPI.

Sulphur.IncitecPivot

Fertilisers.

http://www.regional.

org.au/au/asa/1985/

concurrent/cereal-

nutrition/p-08.htm

http://www.ces.ncsu.

edu/plymouth/cropsci/

docs/sulfur.html

i More information

Potassium.IncitecPivot

Fertilisers.
















http://www.incitecpivotfertilisers.com.au/News/Nutrient Facts/Sulphur

http://www.incitecpivotfertilisers.com.au/News/Nutrient Facts/Sulphur

http://www.regional.org.au/au/asa/1985/concurrent/cereal-nutrition/p-08.htm




http://www.ces.ncsu.edu/plymouth/cropsci/docs/sulfur.html



http://www.incitecpivotfertilisers.com.au/News/Nutrient Facts/Potassium

http://www.incitecpivotfertilisers.com.au/News/Nutrient Facts/Potassium



December 2014



historyofmaizeproductioninthenorthernregion,Kdeficiencyinothercropsisbecoming

more common.

SoiltestingandteststripsarerecommendedtohelpintheearlydetectionofKdeficiency.

PotassiumapplicationratesrecommendedbyDAFFarepresentedinTable4.

Table 4: Potassium application rates for dryland and irrigated maize in Queensland (kg/ha)

Area Dryland IrrigatedAthertonTablelands 0–50 0–50

Wettropicalcoast 0–50


DarlingDowns 0–50 0–50

Moreton – 0–50


SymptomsofKdeficiencyinclude:

• ascorchedappearanceontheouterleafedgesofyoungplants

• yellowtobrowndiscolorationonlowerleaves

• acropwithagreatertendencytolodge

• acropwithsmallearsthatfailtofillatthetip 17

MaizerequireslargeamountsofKinquantitiessimilartoN.

Potassiumisessentialforvigorousgrowth,yetisnotapartofproteinsandotherorganic

compounds.Itisvitaltothestructureandefficiencyofthefunctioningofthemaizeplantfor

theproductionandmovementofsugarstothedevelopingears.

PotassiumdoesnotleachtothesameextentasN,nordoesitbecometiedupin

unavailableorslowlyavailableformstothedegreethatPdoes.However,likeP,itshould

notbeplacedinthesurfacelayer,whichwillregularlydryoutandtheKwillbeunavailable

tothegrowingplant. AnyappliedfertiliserKwillbebsorbedbytheclaylatticebeforeitis

available to plant.

ApplicationsofKcanbecarriedoutatanytimeduringlandpreparation.SomeformsofK

fertilisersneedtobeappliedwellinadvanceofplantingtobeavailabletothegrowingcrop.

Agraincropof11t/ha(greenchopof70t/ha)takesup>50%or117kgofitsK

requirementof225kginthefirst55days.TheyoungseedlingdoesnotrequiremuchK,

buttherateofuptakeclimbsrapidlytoapeakinthe3weeksleadingtotasselling.Uptake

ofKpeaksat~4kg/ha.dayduringthisperiod,andbysilking75%ofthetotalKhasbeen

takenup.

AdeficiencyofKshowsasyellowinganddyingofleafmargins,beginningatthetipsofthe

lowerleaves.Symptomsappearingatanearlystagemeanthatthetotalsoilsupplyislow


i More information

Potassium.IncitecPivot

Fertilisers.

JWhite(2003)Potassium

nutritioninAustralian

high-yieldingmaize

productionsystems—a

review.AustralianMaize

Conference.




http://www.incitecpivotfertilisers.com.au/News/Nutrient%20Facts/Potassium

http://www.incitecpivotfertilisers.com.au/News/Nutrient%20Facts/Potassium

http://www.potash-info.com/research/researchprojects/Documents/K for Maize Production - Review.pdf








December 2014



orthattherootsystemisseverelyrestricted,forexampleacompactedsoillayerorsubsoil

constraints.18

5.10 Long-fallow disorder

SoilsnaturallycontainbeneficialfungithathelpthecroptoaccessnutrientssuchasPand

Zn.Theyformasymbioticrelationshipwiththecropthathelpsdevelopingrootsaccess

nutrientssuchasPandZn.

Thecombinationofthefungusandcroprootisknownasarbuscularmycorrhiza(e)(AM),

previouslyVAM.Manydifferentspeciesoffungicanhavethisassociationwiththerootsof

crops.Manythatareassociatedwithcropsalsoformstructurescalledvesiclesintheroots.

TheseverereductionorlackofAMshowsupaslong-fallowdisorder—thefailureofcrops

tothrivedespiteadequatemoisture.Ongoingdroughtinthe1990sandbeyondhas

highlightedlong-fallowdisorderwhereAMhavediedoutthroughlackofhostplantroots

duringperiodsoflongfallow.Ascroppingprogramsrestartafterdryyears,ayielddropis

likelyfromreducedAMlevels,makingitdifficultforthecroptoaccessnutrients.

Long-fallowdisorderistypifiedbypoorcropgrowth.Plantsseemtoremainintheirseedling

stagesforweeksanddevelopmentisveryslow.

BenefitsofgoodAMlevelsare:

• improveduptakeofPandZn

• improvedcropgrowth

• greaterdroughttolerance

• improvedsoilstructure

• greaterdiseasetolerance

Ingeneral,thebenefitsofAMaregreateratlowersoilPlevelsbecauseAMincreasea

plant’sabilitytoaccessthisnutrient.Sorghumhasamediumdependencyonmycorrhizae,

andcropswithhigherdependencybenefitmorefromAM(Table5).19

Table 5: Dependency of various crop species on mycorrhizae (value decreases as the phosphorus level of the soil increases)

Mycorrhizal dependency

Potential yield loss without mycorrhiza (%)

Crops

Veryhigh >90 Linseed

High 60–80 Sunflower,mungbean,pigeonpea,maize,chickpea

Medium 40–60 Sudangrass,sorghum,soybean

Low 10–30 Wheat,barley,triticale

Verylow 0–10 Panicum,canarygrass

Nil 0 Canola,lupins


19 DAFF(2010)Nutrition—VAMandlongfallowdisorder.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/nutrition-management/nutrition-vam

i More information

Nutrition—VAMandlong

fallowdisorder.DAFF

Qld.

GRDC(2009)

Mycorrhizaeandtheir

influenceonPnutrition.

GRDCUpdatePapers.

VCozzolino et al.(2013)

Impactofarbuscular

mycorrhizalfungi

applicationsonmaize

productionandsoil

phosphorusavailability.

Journal of Geochemical

Exploration 129.

JZhuet al.(2005)Topsoil

foragingandphosphorus

acquisitionefficiency

inmaize(Zea mays).

Functional Plant Biology

32.




http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/nutrition-management/nutrition-vam























December 2014



5.11 Micronutrients

5.11.1 ZincMaizeissusceptibletoZndeficiency.Zincmaybeappliedtosoilorasfoliarfertiliser.

Forsoilapplication,apply30kg/haofzincsulfatemonohydrateorzincoxideintothesoilat

least3monthsbeforeplanting.Thismaycorrectthedeficiencyforupto8years.

Forfoliarapplication,apply2–4weeksafteremergence.Asecondapplicationmaybe

required2weekslater.Apply1–1.5kgofzincsulfateheptahydrateandanequalamountof

ureain100Lofwater.Applyatarateof100L/ha.

Ifthewaterishard(i.e.withhighcarbonatelevels),thewaterwillturncloudyasinsoluble

zinccarbonateisproduced.Trickleinsulfuricacid(e.g.batteryacid)asthetankisfilling.

Therateis50mL/100L.ThiswillmaketheZnavailabletoplants.

Zincchelatesareverycompatiblewithherbicidesandcanbeusedatsowinginamixasa

fluidstarterwiththeseed.ReadtheZnproductandherbicidelabelstoensurecompatibility.

OtherZn-basedproductsareavailable.Iftheseareused,followthelabeldirections.

SymptomsofZndeficiencyinclude:

• lightstreakingfollowedbyabroadwhitishband,startingslightlyinfromtheleafedge

andextendingtothemidrib

• leafedges,midribandtipthatremaingreen

• plantsstuntedwithshortinternodes

• newleaveswithsometimesnearlywhiteleafedgesandstalksofapurplishcolour20

Zincisagrowthregulator.MaizeisparticularlysensitivetosoilZndeficiencies,particularly

onheavyclaysoilswithahighpHandundercoolconditionsearlyintheplantlife.Cutareas

willoftenbedeficientinZnforafewyears.MostoftheZnistakenupinthefirst4weeksof

theplant’slife;therefore,itmustbeavailablefromdayone.

OnceZndeficiencysymptomsareevident,yieldlossesarealreadybeingexperienced.

Maizegrowerscroppingonsusceptiblesoilsshouldimplementalong-termprogramto

overcomeZndeficiencies,usingzincoxideorzincsulfatemonohydratewellinadvance.

Zinccanbeappliedbywaterinjectionusingzincsulfateheptahydrate,meaningitisreadily

available.Often,foliarapplicationsareappliedwhensymptomsareevident,andtwo

applicationsmayberequiredforaseverelyaffectedcroptorecover.

FertilisercompaniesnowhaveZninsomestarterfertiliserblends,whichlendsitselftoan

ongoing program. 21



i More information

BJAlloway.Zincinsoils

and crop nutrition. IZA

and IFA.






http://zinc-crops.ionainteractive.com/publications/Zn_in_Soils_and_Crop_Nutrition_2008.pdf





December 2014



MaizeplantsareratedashavingmoderatetohighsusceptibilitytoZndeficiency.

Zincisnecessaryearlyintheplant’sgrowth,duringthefirst3weeks.Responsestoapplied

NandPmaybeaffectedifthelevelofavailableZnislow.

SoilswithahighpH(>7.0),erodedsoils,orland-formedsoilsaremostatriskofZn

deficiency.

Aswithothernutrients,yieldlossescanoccurbeforevisiblesymptomsoccur.Typical

symptomsarelight,parallelstripingfollowedbyabroadwhitishbandstartingslightlyin

fromtheleafedgeandextendingtothemidrib.Theleafedges,midribandtipoftheleaf

remain green.

SoilapplicationsofZnareexpectedtolastseveralyears,withratesof10–20kgZn/ha

effectivefor4–5years.DependingontheformofZnused,applicationsmayneedtobe

madewellinadvanceofthecrop.

Foliarapplicationsduringwaterloggingperiodsearlyinthecrop’sdevelopmentcanbea

usefulmanagementtoolinhelpingthecropovercomeassociatedstress.

Waterinjectionand/orfoliar(1%solution)applicationsofZngenerallyusezincsulfate

heptahydrateorchelatedzincforovercomingZndeficiencies.Foliarapplicationsgenerally

needtwospraysabout7–10daysapart,2–3weeksafteremergence. 22

5.11.2 MolybdenumSeednormallyhassufficientMo,althoughdeficienciescanoccasionallyoccurinacidsoils,

especiallythosethatarehighlyleached.Molybdenumdeficiencycanbetreatedwithafoliar

sprayofsodiummolybdateat300g/ha.Thisisappliedwhenthereissufficientleafarea

(e.g.30daysafterplanting).

Symptomsofmolybdenumdeficiencyinclude:

• tipsofthelowerleavesturningyellow,browningoffanddyingshortlyafterplant

emergence

• manyplantsinacropdyingcompletelyandothersbeingshortandstunted

DeficienciescanbecorrectedbyapplicationofMomixedwithotherfertilisers.Thismay

correctthedeficiencyforupto5years. 23

ThemainfunctionforMoinamaizeplantisintheenzymesystemfornitratereduction.

Molybdenumdeficiencyisnotusuallyaproblem,butsomecoastalacidsoilscan

bedeficientandthesituationiseasilycorrectedwiththeadditionofmolybdenised

superphosphate.24




i More information

Copper. Incitec Pivot

Fertilisers.

Nutrientsourcesfor

crops.IncitecPivot

Fertilisers.








http://www.incitecpivotfertilisers.com.au/Products Services/Nutrient Facts/Copper

http://www.incitecpivotfertilisers.com.au/Products Services/Nutrient Facts/Copper

http://www.incitecpivotfertilisers.com.au/News/Latest News/Horticulture Extra/Nutrient sources for crops





December 2014



5.11.3 Magnesium (Mg)Magnesiumdeficiencyisusuallyassociatedwithstronglyacid,sandysoilsinmoderateto

heavyrainfallareaswheretheMgcanbeleachedfromthesoil.

Characteristicsymptomsareyellowstreakingofthelowerleavesbetweentheveins,

sometimesfollowedbydead,roundspots.Theolderleavescanbecomereddishpurple.

Broadcastapplicationsofdolomiteshouldbethemosteconomicallong-termtreatment.

Magnesiumsulfate(Epsomsalts)isusedifafoliarsprayisneeded. 25





Section 6 MAIZE - Weed control


December 2014



SECTION6

Weed control

Weedscompetefornutrientsandwater,whichcancontributetocropstressifnotproperly

managed.Weedsmayalsocreateharvestproblemsandincreasemarketingcosts.Crop

rotations,plantingintoweed-freeseedbeds,inter-rowcultivationsandherbicidesareall

techniquesforcontrollingweeds.Topreventsignificantyieldloss,weedsmustbecontrolled

within4–5weeksofplanting.

Herbicidesmaybeappliedatpre-plant,pre-emergence,post-plantorpost-emergence.

Beforeusingherbicides,alwaysreadthelabel.DonotusetheherbicidesDual®(active

ingredientS-metolachlor)orPrimextra®(S-metolachlor+atrazineDualGoldmetalochlor)or

PrimextraGold(Metalochlor+Atrazine)withwaxymaizevarieties.1

Alwayscheckrates,thetypesofweedscontrolled,andapplicationandsafetyguidelineson

thelabel.2

Goodweedcontrolisveryimportantforhighyieldsinmaize,asitiswithothersummer

crops.Weedscompeteverystronglyformoisture,nutrientsandlight.Grassweedsare

themostcompetitiveandmustbeeliminatedearly.However,broadleafweedswillalso

competestronglywithmaize.Maizeisquitesensitivetoweedcompetitionintheearly

stagesofgrowthuntilitreachesabout0.8minheight.

Aswellasadetrimentaleffectonyourmaizecropyield,weedscancreateproblemsat

harvesttimebyblockingharvestingfrontsandsieves,orbycausingdockageinpayments

whenthegrainisdelivered.Inseverecases,weedscancausethegraintoberejectedfor

receivalbythecustomer.

Weedcontrolcanbecarriedoutbyeithermechanicalorchemicalmeans,orthe

combinationofboth.3

1 DAFF(2012)Nutrition,irrigationandweedsformaize.DepartmentofAgriculture,FisheriesandForestry,Queensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/nutrition-irrigtion

2 DAFF(2012)Nutrition,irrigationandweedsformaize.DepartmentofAgriculture,FisheriesandForestry,Queensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/nutrition-irrigtion

3 Growthpotential.Corngrowers’workshop.PioneerHi-BredAustralia,http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Corn_Workshop_Book.pdf

i More information

JEPratley(2006)

Allelopathy—newweed

controloptionsfor

maize.In6thTriennial

Conference, Maize


RMitchell,TDixon.

Competingcrops

combatingweeds.The

Cob, autumn 2014, p. 7.

KBecker(2014)Plan

nowforsummerdouble

crops. GRDC Media

Centre.

JFleminget al.(2013)

Weedcontrolinsummer

crops2012–13.NSW

DepartmentofPrimary

Industries.



Authority.

DAFF(2013)Agvet

chemicalsand

residues.Departmentof


ForestryQueensland.








http://www.maizeaustralia.com.au/events_files/Allelopathy - JE Pratley.pdf






















http://www.daff.qld.gov.au/plants/agvet-chemicals-and-residues







December 2014



6.1 Competition from weeds

Yieldlossesfromweedcompetitioninmaizevaryfromnegligibletototalcroploss.

Weedshavethegreatestcompetitiveeffectonmaizeinthefirst3–4weeksaftersowing,

soearlycontrolisessential.Oncethemaizecrophasreached80–100cmhighitcan

effectivelycompetewithmostweeds.

Maizeissensitivetomoisturestress,sotheearlycontrolofweedsisparticularlyimportant

innon-irrigatedcrops.Weedscancausereductionsinyieldthroughcompetitionforwater,

sunlightandnutrients.

Weedssuchasbellvine(Ipomoeaspp.)canalsocausesignificantproblemsatharvest,

whereasnoogooraburr(Xanthium pungens)andDaturaspeciescancauseweedseed

contaminationofgrain,leadingtorejectionbythebuyer.

Failuretocontrolweedscanalsoleadtoanarrowingofenterpriseoptionsforthefuture.

For example, failure to control noogoora burr and Datura in a maize crop will eliminate

sunflowersasafutureoptionduetolimitedcontroloptions.

Successfulmanagementofweedsinmaizecropscomesthroughplanning,paddock

selection,timelinessofoperationsandawillingnesstouseawiderangeofweed-

managementoptions.

Relianceonasinglemethodofweedcontrolwillleadtoa‘speciesshift’orherbicide

resistanceifthereisamajorrelianceononeherbicidegroup.Aspeciesshiftiswhere

onecontroltechniqueisrepeatedlyused,leadingtoanincreaseinnumbersofoneor

moreweedspeciesnotcontrolledbythattechnique.Anexampleisthecontinueduse

ofmetolachlor(Dual®)withoutotherweed-managementtechniques,whichleadstoan

increaseinbroadleafspeciessuchaspigweed(Portulaca oleracea)orDatura. 4

6.2 Main weed species of concern in maize crops

Althoughmaizeisgrownacrossawideandvariedgeographicalarea,weed-management

techniquesremaincommonacrossthisrangeofenvironments.Tables1–4listsomeofthe

mainweedspeciesencounteredinmaizeineasternAustralia.5

4 AStorrie(1997)Australianmaize.KondininGroup.

5 AStorrie(1997)Australianmaize,KondininGroup.v




December 2014



Table 1: Grass weeds of maize by region

Grasses North Qld

Sth Burnett/Darling Downs

Northern NSW

NSW North Coast

Riverina/Victoria

Mossmanrivergrass(Cenchrusspp) P PCrowsfootgrass (Eleusine indica) P P P PBarnyardgrass (Echinochloaspp) P P P PSummergrass (Digitariaspp) P P P P PGuineagrass (Panicum maximum) P PPigeongrass (Setariaspp) P P P PLiverseedgrass (Urochloa panicoides) P PStinkinglovegrass (Eragrostis cilianensis) P P PJohnsongrass (Sorghum halepense) P P P P PRhodesiansudangrass (S bicolorssparundinaceum)

P

Couchgrass (Cynodon dactylon) P P P P PWatercouch (Paspalum distichum) P P P

Table 2: Sedges and rushes

Sedges North Qld


Northern NSW

NSW North Coast

Riverina/Victoria

Nutgrass (Cyperus rotundus) P P P PUmbrellasedge(Cyperus eragrostis) P P




December 2014



Table 3: Broadleaf weeds in maize by region

Broadleaf weeds North Qld


Northern NSW

NSW North Coast

Riverina/Victoria

Amaranth (Amaranthusspp) P P P PAnnualgroundcherry(Physalis angulata) P P PApple of Peru (Nicandra physalodes) P P PBathurstburr (Xanthium spinosum) P P P PBellvine (Ipomoeaspp) P P PBlackberrynightshade(Solanum nigrum) P P P P PBladderketmia(Hibiscus trionum) P P P PCaltrop (Tribulusspp) P P PCobbler’speg (Bidens pilosa) P P P PCommon verbena (Verbenaspp) P P P PEuphorbia/Spurge (E. davidii or E. dentata) P PFathen (Chenopodium album) P P P PMintweed (Salvia reflexa) P P PNoogoora burr (Xanthium pungens) P P P PPigweed (Portulaca oleracea) P P P PSesbaniapea (Sesbaniaspp) P P P PSida (Sidaspp) P PSowthistle (Sonchusspp) P P P PStarburr (Ancanthospermum hispidum)

P P P P

Stinkingroger (Tagetes minuta) P P PThornapple (Daturaspp) P PTurnip weed (Rapistrum rugosum) P P PWandering jew (Commelina benghalensis)

P P

Wildgooseberry(Physalis minima) P P P




December 2014



Table 4: Herbicides registered in Australia for use in maize

Herbicide Queensland and NSW

Victoria Tasmania, SA and WA

Pre-plant

Eptam(EPTC) P Patrazine(various) P P P

Post-plant pre-emergence

atrazine(various) P P Patrazine+Dual P P Patrazine+Stomp P P PDual(metolachlor) P P PPrimextra(atrazine+Dual) P PStomp(pendimethalin) P P PPrimextra+Dual P Plinuron(various) P P PRamrod(propachlor) P P P

Post-emergence

2,4-D(various) P P Patrazine(various) P P Patrazine+2,4-D P P Patrazine+dicamba P P Patrazine+Tordon75-D Pdicamba(Banvel200) P P Plinuron(various) P P PMCPA(various) P PTordon75-D(picloram+2,4-D) P

Pre-harvest

2,4-D(various) P

6.3 Forms of weed control

Awiderangeoftechniquesshouldbeusedifsustainableagriculturalproductionisthelong-

term aim.

Weedcontrolbeginswiththepreviouscropsandpastureswhereweedsshouldhavebeen

preventedfromsettingseed.Planningwithearlierapplicationofherbicidesorselectinga

‘clean’paddockcanhelppreventmajorproblems.6

6.3.1 Mechanical weed controlMaizeisusuallyplantedinrowsupto1mapart,andtherefore,inter-rowcultivationcanbe

practiced.Inter-rowcultivationcanbedoneuntilthemaizecropreachesabout0.75min

height.Afterthat,thecropcanopyclosesoverandthemaizecompeteswellwithweeds.

6 AStorrie(1997)Australianmaize,KondininGroup.




December 2014



Inter-rowcultivationmustbeshallowtopreventrootpruningofthecropbutcansometimes

beadvantageousinmaizecropstoencouragerootdevelopmentanddeeperrootsystems..

Wetconditionsmaypreventcultivationatcriticaltimesand/orcausetransplantingof

weeds. 7

6.3.2 Mechanical and chemical weed controlBandsprayingofchemicalsinthecroprowcombinedwithinter-rowcultivationisawidely

usedpracticeinalltypesofsummercrops. 8

6.3.3 Chemical weed controlSeveralchemicalsareavailablethatwillgiveverygoodweedcontrolthroughthelifeofthe

maizecropifusedcorrectly.Alwaysreadthelabelbeforestartingtospray). 9Maizecrops

areannualinnatureandweedescapesareverycommonbetweenphysiologicalmaturity

andharvest.

6.4 Farm hygiene

Controllingweedinfestationsalongfencelines,roadways,channelsandbuildingswill

minimiseweedspread.Newweedswillinfesttheseareasfirst,beingcarriedinby

machineryorlivestock.Theyarealsothesourcesofseedtore-infestfields.

Theseareascanbekeptweed-freebysowingperennialpasturespecies,whichcanbe

periodicallyslashedormanagedwithacombinationofherbicidesandcultivation.10Itis

importantnottochooseaChlorissp.whicharecurrentlymajorsourceofsummergrass

resistancesuchasfeathertopRhodesgrassandwindmillgrass.

6.5 Crop rotation

Rotationsshouldbeflexibleenoughtotakeaccountofvariationsinmarketsandweather.

Theidealistoalternatebetweenbroadleafandcerealcrops,andwell-managedpastures.

Thisallowscultivation,herbicidesandgrazingtobeused.Forexample,alternatingbetween

summercropsandwintercropswiththeoccasionallongfallowwillpreventthebuildupof

anyoneweedspecies.11



9 http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Corn_Workshop_Book.pdf

10 AStorrie,AustralianMaize,KondininGroup1997

11 AStorrie(1997)Australianmaize.KondininGroup.

i More information


growers’workshop.

Pioneer Hi-Bred

Australia.



Authority.















December 2014



6.6 Maize growth stages

Figure1describesthegrowthstagesofmaize.

Figure 1:

15 cm35 cm

65 cm

Stage V2 – Two leaf stageOnly count leaves which have the leaf collar visible. Occurs about one week after emergence. Growing point below soil surface – plants survive hail and light frosts. First set of secondary roots developed. Weeds start to reduce yields significantly. Start spraying most post-emergent herbicices.

Stage V5 – Five leaf stageOccurs about three weeks after emergence. Growing point at soil surface. Tassel and ears initiated. Total leaf number determined. Two sets of secondary leaves developed. Weeds significantly reduce yields. Use drop nozzles for most post-emergent herbicides.

Stage V8 – Eight leaf stageOccurs four to five weeks after emergence. Two lowest leaves may be lost. The leaf stage is now determined by splitting the stem lengthwise. Use the first node above the first elongated internode (usually the fifth leaf node) as the reference point. Growing point about 5 to 7 cm above soil surface. Yields may be reduced by hail and frosts.Too late to use most post- emergent herbicides.

Maize growth stages. (Source: NSW DPI)

6.7 Pre-emergent herbicides

Pre-plantorpre-emergentweedcontrolofgrassesisessentialinmaize.Similarly,broadleaf

weedcontrolispreferableatthisstage.Inseekingflexiblecroppingoptions,farmersoften

avoidtheuseofresidualherbicide,especiallyforgrasscontrol.12

Summerweedsandgrassesareveryaggressiveandcompetewithyoungmaizeplantsfor

moisture,nutritionandlight.Therefore,earlyweedcontrolisessentialinmaizecropsbefore

thecanopyshadesthesoilsurface.

Traditionalcultivationwillhelptoreduceweedcompetitionveryearlyon,butnotpost-

planting.Inter-rowcultivationonitsownorcoincidingwithsidedressingisanothermethod

ofmechanicalweedcontrol.

12 JFleming,TMcNee,TCook,BManning(2012)Weedcontrolinsummercrops2012–13.NSWDPIManagementGuide.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0008/248471/Weed-control-in-summer-crops-2012-13.pdf

i More information


Weedcontrolinsummer

crops2012–13.NSW

DepartmentofPrimary

Industries.


growers’workshop.

Pioneer Hi-Bred

Australia.















December 2014



Byfarthemostefficientandeffectiveformofweedcontrolisuseofherbicides.Averygood

rangeofherbicidesisregisteredforweedcontrolinmaize,rangingfrompre-emergent

throughtopost-emergent(Figure2).

Figure 2:

Stage VE V2Emergence

Planting

Height (cm)

Days

0

-6 -2 0 7 18 28 42 56 65 100

10 30 60 270 270

2 leavesfully

emerged

8 leavesfully

emerged

12 leaves 16 leaves Pollination20 leaves

Dent5 leavesfully

emergedTassel and ear initiation

V5 V8 V12 V16 R1 R5

Pre-plant application

Post-emergent application

2-3 leaves

Post-sow

ing pre-emergent application

Avoid spraying

Avoid spraying

Harvest aidAtrazine

Dicamba

2,4-D amine

StaraneTM Advanced

MCPA 250

from doughstage

2,4-D amine

10-20cm

10-90 cm or 15 days prior to tasselling

3-5 leaves 6 leaves to tasselling: use droppers

20 cm - before tasselling: drop nozzles only

10-60 cm: drop nozzles only

Timing of herbicide application in maize. (Source: NSW Agriculture)

Alwaysreadtheapplicationdirectionsonthelabel.Someresidualherbicideshaveplant-

backrestrictionsforfollowingcrops,socarefulplanningofaherbicideprogramisrequired

toensurecroppingoptionsarenotrestricted.

Itisthereforeimportanttounderstandtheherbicidehistoryoftheparticularpaddocks—a

residualherbicidetowhichmaizeissensitivemayhavebeenappliedonapreviouscrop.

Someoftheregisteredherbicidesusedinmaizeeitherontheirownorincombination

include atrazine, Dual Gold®, Primextra®, Stomp®(pendimethalin),Starane™Advanced

(fluroxypyr),andthehormonechemicals(post-emergent)Starane®, 2,4-D amine, dicamba

and Tordon 75D®(picloram+2,4-D).

Forcurrentregisteredchemicalsforuseinmaize,visitwww.apvma.gov.au

Ofthehormonechemicals,Starane®(fluroxypyr)isthesoftestonmaize,andattention

shouldbegiventothetimingofapplicationoftheseherbicidestoensurethattheyare

appliedatthecorrectstageandthecropisnotunderstress.





December 2014



Useofdroppersisrecommendedbetweentherowstoavoidapplyingchemicaltothe

whorl.Otherwise,damagetothereproductivepartsoftheplantandlodgingcanresult.

Formoredetailedinformationonherbicidesandtheirapplication,contactyourlocal

agronomist,resellerorchemicalrepresentative.

Farmhygieneshouldalsobemaintainedaroundfencelines,storagedams,waterwaysand

channelstokeeptheweedseedbankincheck.Finally,cleancropsandsurroundingareas

willhelpreducethebuildupofinsectsandsomediseases.13

6.8 Post-plant pre-emergent herbicides

Weedsshouldberemovedfrommaizewithin3–4weeksofemergencetopreventyield

loss.Theextentofyieldreductiondependsontheweedspecies,weedandcropdensity,

andthesizeofweedswhencontrolmeasuresareapplied.Thestagesofweedandcrop

growtharevitalfactorswhenplanningsuccessfulpost-emergentherbicideuse.Read

herbicidelabelscarefullyforthesedetailsandinformationonoptimumconditionsfor

spraying. 14

6.8.1 Imidiazolinone technologyTheI.T.traitincorporatedinsomeofthePacificSeedshybridmaizerangemeans

‘imidazolinonetolerance’.hybridsstandsfor‘Imidazolinoneisafamilyofherbicideswiththe

potentialtocontrolmanyimportantweedspeciesthatcauseyieldandqualityreductionin

manymaize-growingregionsofAustralia.

TheI.T.orClearfield®traitformaizeisanon-GMO(non-geneticallymodifiedorganism),

herbicide-tolerantcroppingsystem.I.T.herbicideresistancewasdevelopedin1988using

traditionalplant-breedingtechniques.Thisresearchisolatedanaturallyoccurring,dominant

innature.ThismeansthatanI.T.maizeparentlinecanbecrossedtoanon-I.T.parentline

toproducehybridseedthathascompletetolerancethroughitsdominantnature.

MaizehybridswiththeI.T.traithaveshownnosignificantyieldpenaltycomparedwith

conventionalhybrids.

InAustralia,theherbicideregisteredforuseonI.T.varietiesisLightning®(imazethapyr+

imazapyr),abroad-spectrumherbicideforknockdownandresidualweedcontrol.

BecauseoftheresidualeffectofLighting®,carefulconsiderationshouldbegiventoplant-

backintervalsforcropsthatfollow.Plant-backperiodsvarydependingonthecroptobe

plantedandenvironmentalconditions.Refertoproductlabelformorecomprehensive

details.15RapiddevelopmentofgrassweedresistancewithIMIherbicidesisariskifnot

usedstrategically.

AustralianPesticidesandVeterinaryMedicinesAuthority.


14 JFleming,TMcNee,TCook,BManning(2012)Weedcontrolinsummercrops2012–13.NSWDPIManagementGuide.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0008/248471/Weed-control-in-summer-crops-2012-13.pdf

15 PacificSeedsAgronomyNotes

i More information


au/__data/assets/pdf_

file/0008/248471/Weed-

control-in-summer-

crops-2012-13.pdf

http://www.nufarm.com/

NZ/Maize

JFleminget al.(2013)

Weed control insummer

crops2012–13.NSW

DepartmentofPrimary

Industries.

Topofthecrop.Aguide

toprotectingyourmaize

cropandmaximising

yield.NufarmLtd.

i More information


Weedcontrolinsummer

crops2012–13.NSW

DepartmentofPrimary

Industries.

i More information

www.apvma.gov.au

http://www.agro.

basf.com.au/

images/pdf/labels/

Lightning52742_0801_

TXT_Label.pdf












http://www.nufarm.com/NZ/Maize

















http://www.agro.basf.com.au/images/pdf/labels/Lightning52742_0801_TXT_Label.pdf







December 2014



6.9 Potential herbicide damage effect

Dealingwithlargenumbersofweedinsummerfallowisasignthatstrategiesforseedbank

managementarenotworking.

Widespreadadoptionofno-tillfarminghasseenaspeciesshifttoweedsadaptedto

surfacegermination.

Over-relianceonglyphosateinthefallowisleadingtorapidexpansionofglyphosate

resistance.

Integratedweedmanagementstrategiesareavailabletomanagekeyspeciespresentin

thesummerfallowthroughthenortherngrainsregion.Growerswhohavezerotoleranceto

weedsproducingseedscandriveseedbanksformanyweedstoverylowlevelswithin1–3

years.

Growerswhohavetheweedseedbankundercontrolwillsaveherbicidecosts,havegreater

rotationalflexibility,havegreateroptionstousediversetacticsthatwouldotherwisebecost

prohibitive,and,byreducingthefrequencyofherbicideapplications,willdelaytheonsetof

herbicideresistance.16

16 MCongreve(2014)Managingherbicideresistantweedsinthesummerfallow.GRDCUpdatePapersJuly2014,http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2014/07/Managing-herbicide-resistant-weeds-in-the-summer-fallow

i More information

http://www.grdc.com.

au/Research-and-

Development/GRDC-

Update-Papers/2014/07/

Managing-herbicide-

resistant-weeds-in-the-

summer-fallow

MCongreve(2014)

Managingherbicide

resistantweedsinthe

summerfallow.GRDC

UpdatePapersJuly

2014.

I Rajcan et al.(2001)

Understandingmaize–

weedcompetition:

resourcecompetition,

lightqualityandthe

wholeplant.FieldCrops

ResearchVol. 71.
























Section 7 MAIZE - Insect control


December 2014



SECTION7

Insect control

Severalpestscanattackmaizeplantsduringthevegetative,reproductionandgrainfill

stages,themostsignificantbeingthecornearwormorHelicoverpalarvaeand,insome

areas,thetwo-spottedspidermite.Othersthatcancauseyieldlossarethecornaphid,

redshouldered(Monolepta)beetle,greenvegetablebug,locustsandmaizeweevil.

InseasonswhenHelicoverpahaveoverwinteredandnumbersarehighearlyintheseason,

thereisanearlyegglayevidentbyperforatednewleaves.Hatchinglarvaewillforageon

tasselsandsilks,andifinfestationissevere,theycancutthesilks,offreducingseedset.

Oncethelarvaegrow,itisuncommontohavemorethanoneineachcobtip.Theyusually

donotdoalotofdamageatthisstage,unlessthenumbersarehigh,andthentheymay

startburrowingintothesideofthecob.Ifthisoccurs,thesecobsarepredisposedtocob

rots. 1

AgronomistsreportthatHelicoverpalarvaecausingcobdamagearelaidwhenthetassels

andsilksareestablished.Eggsthatarelaidinthevegetativestagehavealreadyfinished

theirlifecyclebythetimesilksandtasselshaveemerged,sodamagetoreproductiveparts

oftheplantisgenerallyrestrictedtodevelopingtasseldowninthewhorl.

Ifsignsofalargeegglayappear,spraypriortocanopyclosure.Ifsprayingisleftuntil

silkingorlater,itwillbedifficulttoachievechemicalpenetrationintothecanopy.Ifyousee

largelarvae(30–50mm)inthecrop,itistoolatetospray;theywillbenearlyimpossibleto

control. 2MostattemptsatcontrollingHelicoverpadamagetocobsaretimedatsilkingand

tasselingwhenneonateshavehatched.



i More information

K.Charleston(2013)

Maizeinsectpest

management.Northern

grainsregion.DAFF

Queensland.

PUmina(2014)

Persistentpests:aphids,

mites,millipedesand

earwigs.GRDCUpdate

Paper.

National Invertebrate

PestInitiativeIPM

Guidelineshttp://

ipmguidelinesforgrains.

com.au/crops/maize/






http://ipmworkshops.com.au/wp-content/uploads/Maize_IPM-Workshops_north-March2013.pdf





http://grdc.com.au/Research-and-Development/GRDC-Update-Papers/2014/02/Persistent-pests-aphids-mites-millipedes-and-earwigs





http://ipmguidelinesforgrains.com.au/crops/maize





December 2014



7.1 Maize pests by crop stage

Pestscanoccuratoneormoregrowthstages.3

Table 1: Maize pests by crop stage

Pest

Crop stage

Emergence Vegetative Silking/Tasselling

Grainfill

Blackfieldearwig PWireworms PCutworms PMaizethrips P PMaizeleafhoppers P PLocusts PWhitegrubs PArmyworm PSwarmingleafbeetles PRedshoulderedleafbeetles PGreenvegetablebugs P PCornaphids PHelicoverpa P P PTwospottedmites PRedbandedshieldbug PYellowpeachmoth P

7.2 Early pests

Plantingisthesinglemostimportantoperationinthefarmingsystemandopportunitiesto

plantarevaluable.Therefore,itisimportanttoensurethatemergingseedlingsareprotected

fromseedlingpestssuchasinsectsandmice.

Attackfromthesetypesofpestissporadicfromseasontoseasonandfieldtofield,soitis

difficulttoanticipatetheiroccurrenceandnumbers.Regularinspectionofemergingcropsis

essential.

Maizeisparticularlysensitivetovariationinplantspacing(theeffectofunevenplantspacing

inmaizeisestimatedtocostgrowersonaverage400-500kg/ha).Recently,growers,

recognisingtheimportanceandyieldbenefitsofevenseedspacing,havemadeeffortsto

ensurethebestresult.Thiseffortcouldbewastedifgrowersthenignoretherisksofearly

pests.

Themostlikelyseedlingpestsareground-dwellinginsectssuchasfalsewirewormand

cutworm,abovegroundpredatorssuchasnorthernarmywormandmice,andsapsuckers

suchasthrips,aphids,fieldcricketsandearwigs.

3 DAFF(2012)Insectpestmanagementinmaize.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/ipm-information-by-crop/maize#cropstage

i More information

RLNielsen(1997)

Standestablishment

variabilityincorn.Purdue

University.


http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/ipm-information-by-crop/maize#cropstage








December 2014



Thebestdefenceagainstmanyground-dwellinginsectsisanintegratedattackthat

includesgoodweedcontrol,well-controlledplantingdepthandevenness,sowingintogood

moisture,warmsoil,andqualityseedtreatedwithaninsecticide.Evenwithbestpractice,

thedesiredresultisnotguaranteed,andearly-plantedcropsusuallycomeunderthemost

pressure.Falsewirewormsinparticulararegenerallyinabundanceearlyintheseason,so

plantingwithoutseedtreatmentisnotrecommended. 4

7.2.1 MiceMiceseemtobeincreasinginimportanceasapestofagriculturalcrops;damagecaused

bymicetoagricultureisestimatedatAU$10–30million.

AreasontheeasternandcentralDarlingDownsarealreadyincurringdamageinwinter

crops,andsomebaitinghasalreadystarted.ThewesternDownsisatmoderateriskand

micenumbersaroundMungindiarereportedashigh.Miceliketooverwinterinno-till

sorghumpaddocksandintabledrains.Asfoodsupplydiminishesintheseareas,they

migratetowintercrops.

Ifleftuncontrolled,theycancausehighlevelsofdamageinthewintercropandcanmove

tothesummercrops.Micetendtocausetheirworstdamageindryyearswhenwaterand

foodareshort.Inthoseyears,theywillattackdevelopingheadsinthestemoratthemilky-

doughstage,causingmuchmoredamagethaniftheyattackjustthehardgrainforfood. 5

7.3 Soil insects

Themajorityofestablishmentpestsaresoil-dwellinginsects.Soilinsectscanreduceplant

establishment,plantpopulations,plantgrowth,andsubsequentyieldpotential.Monitorfor

soilinsectspriortoplanting.

Variouscultivationsystemsandfarm-managementpracticescandirectlyinfluencethe

compositionandabundanceofpestspecies:

• Weedyfallowsandvolunteerplantsencouragesoilinsectbuild-up.

• Insectnumbersdeclineduringacleanlongfallowbecauseofalackoffood.

• Retainingstubblecanpromotesomesoilinsectsbutcanreducetheamountof

damagetogerminatingcropsastheinsectscontinuetofeedonstubble.

• No-tillageencouragesbeneficialpredatoryinsectsandearthworms.

• Incorporatingstubblepromotespopulationsofblackfieldearwig.

• Falsewirewormsarefoundunderallintensitiesofcultivationbutdeclineifstubblelevels

areverylow.6

4 Earlypestofsorghumandmaize.PacificSeeds,http://www.pacificseeds.com.au/info-and-tools/agronomy-topics/78-early-pest-of-sorghum-and-maize.html


6 K.Charleston(2013)Maizeinsectpestmanagement.Northerngrainsregion.DepartmentofAgriculture,FisheriesandForestryQueensland,http://ipmworkshops.com.au/wp-content/uploads/Maize_IPM-Workshops_north-March2013.pdf










December 2014



7.3.1 Monitoring for soil insectsSoilinsectcontrolmeasuresneedtobeappliedatsowing.Soilinsects,particularly

damagingjuvenilestages,cannotbecontrolledoncethecropisplanted.Inhigh-risk

situations(e.g.followingaweedyfallow,highstubble,orhistoryofsoilinsects),checkfor

pestsusingthefollowingtechniques:

1. Soilsamplingbyspade

• Takeanumberofspadesamples(deepenoughtotakeinthemoistsoillayer)from

randomlocationsacrossthefield.

• Hand-sortsamplestodeterminetypeandnumberofsoilinsects.

2. Germinatinggrainbaittechnique—immediatelyfollowingrainandbeforeplanting

• Soakinsecticide-freecropseedinwaterforatleast2htoinitiategermination.

• Buryasmallhandfuloftheseedunder1cmofsoilateachcornerofa5mby5m

squareatfivewidelyspacedsitesper100ha.Ifthesoilisdry,placeseedinmoisture,

orwaterthebaitstoensuregermination.

• Markthebait’sposition;largepopulationsofsoilinsectscancompletelydestroythem.

• 5–10daysafterplacingbaits,digupthegerminatedseedandcheckforinsects(Table

2).

• Trialshaveshownnodifferenceinthetypeofseedusedwhenitcomestoattracting

soil-dwellinginsects.However,useofthetypeofseedtobesownasacropislikelyto

indicatethespeciesofpeststhatcoulddamageit.

Table 2: Soil insect pest detection thresholds

Soil insect Scouting technique Threshold for controlBlackfieldearwig Germinatinggrainbaits Average 5 per bait

Falsewirewormlarvae Germinatinggrainbaits Average 1 per bait

Wireworm larvae Germinatinggrainbaits Average 1 per bait

Cutworms Cropscoutingafterplanting –

Insecticideseeddressingsprotectthecropfrommostsoil-dwellinginsectsduringthe

seedlingstage.However,monitoringatseedlingstageisrecommendedbecauseseed

dressingsmaygiveonlypartialcontrolofsomeinsectssuchasearwigs,orwhensoil

insectsareabundant.

Paddockswithahistoryofpoorstrikesmayhavehighlevelsofsoilinsects.Seeddusting

helpsdeterinsects.In-furrowsprayinghelpsprotectyoungrootsandshoots.Press-

wheelscanreducedamagefromfalsewirewormlarvaeandearwigsbyencouragingplant

emergenceandfirmingthesoiltoreducetheinsects’abilitytomovethroughit.Soilbaiting

mayreducedamagebyblackfieldearwigsandcrickets,whichattackthetipsofdeveloping

prop-roots(secondaryroots).Shallowplantinginwarm,moistsoilwillencouragerapidcrop

emergenceandgrowth,thusreducingtheeffectofinsects. 7


i More information

KCharleston(2014)

checkforestablishment

pestsbeforeplanting

summercrops.The

Beatsheet.

PGrundy(2014)

Haveyouchecked

forestablishment

pestsbeforeplanting?

AustralianCotton

conference.




http://thebeatsheet.com.au/pests/check-for-establishment-pests-before-planting-summer-crops/





http://www.australiancottonconference.com.au/2014-presentations-papers/grundy-paul-1








December 2014



7.3.2 Black field earwigBlackfieldearwig(Nala lividipes)(Figure1;comparewithpredatoryearwig,Figure2)isa

sporadicandpotentiallymajorpestofmaize.

Figure 1: Black earwigs. (Photo: DAFF Qld)

Figure 2: Predatory earwig attacking a Helicoverpa pupa. Note: predatory earwigs are usually larger than black earwigs and light brown in colour. (Photo: DAFF Qld)

Blackearwigseatnewlysownandgerminatingseedaswellastherootsofcrops,resulting

inpoorestablishment.

Blackearwigsfeedingonsecondaryrootsmaycauseplantstofalloverastheygetlarger.

Seriousdamageisusuallyconfinedtosoilsthatretainmoisturewell,andearwigsprefer

cultivatedsoilstoundisturbedsoil(no-till).

Monitorcropsafterplantinguntilestablishment.Digandsievesoiltodetectadultsand

nymphspriortoplanting.Usegerminatingseedbaitsandcontrolif>50earwigsarepresent




December 2014



in20germinatingseedbaits.Grainbaitscontaininginsecticideappliedatsowingofferbest

protection.Insecticideseeddressingsprovidesomeprotection.In-furrowspraysarenot

effectiveinprotectingagainstdensepopulations.Usepress-wheelsatsowing. 8

7.3.3 True wirewormTruewireworm(Agrypnussp.)larvae(Figure3)boreintogerminatingseedandchewon

seedlingrootsandshoots,resultinginreducedvigour,wiltingorseedlingdeath.Damageis

worsewhencropgrowthisretardedbydry,wetorcoolconditions.

Wirewormsgenerallyfavourmoistareas.Truewirewormlarvaemayalsofeedon

Helicoverpapupae.Usegerminatingseedbaitsorsoilsamplingtodetectlarvaepriorto

sowing.Monitorcropsaftersowinguntilestablishment.Onelarvapergerminatingseedbait

warrantscontrol.Seeddressings,in-furrowspraysandgranularinsecticidesoffersome

control. 9

Wirewormnumbersarenotreducedbyextremedryweather;therefore,along,dryperiod

withnocropwillnoteliminatetheproblem.

Figure 3: True wireworm. (Photo: DAFF Qld)

7.3.4 False wirewormFalsewireworm(Gonocephalumspp.andPterohelaeusspp.)larvae(Figure4)attack

germinatingseedsandseedlingrootsandshootsinspring,resultinginpatchystands.

Damageismostcommoninearly-plantedcropswithlowcropresidue.Adultsmaydamage

summerseedlingsbychewingatorabovegroundlevel,andreplantingmayberequired.

Todetect,eitherhand-sift10soilsamples(30cmby30cm)orplace10germinatingseed

baitsthroughoutthepaddock.Onelarvapersample(orgerminatingseedbait)warrants

control.










December 2014



Preparegroundforevenandrapidgermination.Useofpress-wheelsatplantingprovides

somecontrol.Forlarvae,useseedtreatmentsorin-furrowsprays.Foradults,usecracked

grainbaits.

Naturalenemiesprovidelittlecontrol.Infestationsdetectedaftercropemergencecannotbe

controlled. 10

Figure 4: False wireworm. (Photo: DAFF Qld)

7.3.5 CutwormCutworm(Agrotisspp.)larvae(Figure5)feedonleavesandstemsofyoungplants,andthey

‘cut’downplantstoeattheleaves.Partialdamagetostemsmaycausetheplanttowilt.

LarvaeshelterinthesoilduringthedayandcurlintoaC-shapewhendisturbed.

Cutwormsarefoundinallsoiltypesandoftenmoveintocropsfromadjoiningfencelines,

pasturesorweedyfallows.Cropareasattackedbycutwormstendtobepatchy,andthe

highestriskperiodisduringsummerandspring.

Emergingseedlingsshouldbeinspectedtwiceperweek,particularlyinhigherrisk

situations.Seedlingsshouldbetreatedwhenthereisarapidlyincreasingareaofinfestation

orproportionofcropdamage(>10%seedlingloss).Increasinginfestationsoccurwhere

larvaemovefromweedsorweedyfieldedges.Treatolderplantsif>90%ofsampleshave

oneormorecutwormsorwhenplantshave≥75%leaftissueloss.Spottreatments(e.g.

alongfieldedges)maybesuccessful.Sprayingshouldbedonelateintheafternoonto

increasethelikelihoodofcontactwithfeedingcaterpillars(dusk–night).

Keepfallowscleanandeliminateweedsfrompaddockperimetersatleast1monthbefore

planting.Severedamagetoemergingcropcanoccurwhenlargelarvaeareforcedtomove

fromweedhostsintothecropfollowingsprayingoftheweeds.Cutwormsareattackedby

arangeofnaturalenemiessuchasparasitoids,predatorsanddiseases. 11










December 2014



Cutwormsappearinanumberofpaddockseachyearandtheyarenotcontrolled

byCruiser®(a.i.thiamethoxam)andGaucho®(imidacloprid).In-furrowapplicationsof

chlorpyrifosmaybesuccessfulifcutwormsarepresent;chlorpyrifoshasveryshortresidual

control,soifeggsarelaidaftertheplantingoperation,limitedcontrolcanbeexpected.

Cutwormsareverydifficulttofindindark,moistclaysoilsbecausetheyarethesame

colour.Inrowcropsplantedwithatwindisc,theyareoftenfoundatthebaseofthe

seedlingintheseedtrench.Damagetoseedlingsisoftenthefirstsignoftheirpresence;

typically,cutwormslopofftheseedlingatgroundlevelatnightandpullthegreenmaterial

intothegroundforsafeconsumption.

Fieldsclosetopasture,weedyroad-sidesorfieldswithheavyweedpressureareusuallyat

risk.Somespeciesofcutwormlaytheireggsundertheleavesofweedssuchaswildturnip

andmilkthistle.Chemicalcontroltypicallyrevolvesaroundsurfacespraysofchlorpyrifos

appliedlateintheafternoonoratnight.Controlisusuallyadequate,butunderhigh

pressure,asecondapplicationisoftenneededandreplantingwithin-furrowsprayshas

occurred.Pleaseconsultyourconsultantbeforeapplicationofanychemical. 12

Figure 5: Cutworm. (Photo: DAFF Qld)

7.3.6 Whitegrubs Thesebeetlelarvae(Coleoptera:Scarabaeidae)(Figure6)feedonroots,causinglossof

vigourandlodging.Adultsmayfeedonleaves.

Damageisoftenpatchy,andtherearenoeffectivecontrols,althoughaMetarhiziumfungus

andnematodesarereportedoccasionallytocausehighlarvalmortality.Avoidsowingnew

groundwithmaizeafterpastureinareasthathaveaknownhistoryofwhitegrubs.13



i More information



Authority.











December 2014



Figure 6: Whitegrub. (Photo: DAFF Qld)

7.4 Pests of the vegetative stage

7.4.1 Maize leafhoppersMaizeleafhoppers(Cicadulina bimaculata)(Figure7)aremostcommonduringlatesummer.

Theysucksap,andhighpopulations(>15individuals/plant)cantransmitwallabyear

mycoplasma.Mycoplasma-infectedplantsaredarkgreenwiththickenedveinsonthe

undersideofleaves(Figure8).

Hybridvarietiesoffersomeresistance.Inspectcropsweeklyduringthevegetativestage,

andcontrolif>10leafhoppers/plantandwallabyearsymptomsarepresent.14

Figure 7: Maize leafhoppers (Photo: DAFF Qld)







December 2014



Figure 8: Mycoplasma-infected plants are dark green with thickened veins on the underside of leaves. (Photo: DAFF Qld)

7.4.2 Maize thrips Maizethrips(Frankliniella williamsi)attackseedlingandvegetativegrowthstages.Thripsin

thewhorlcanstopthegrowthofsmallplants.

Infectedplantsmayhaveyelloworsilverypatchesontheleavesandadesiccatedorwilted

appearance.Damageismoresevereifplantsarestressedbydroughtorwaterlogging

andgrowthisslowed,compoundingthedamage.Inspectweeklyduringseedlingand

vegetativestages,andcontrolifthripsarefoundinthewhorlcombinedwithyellowingof

thethroatornecroticstripesonyoungleaves.Seedtreatmentscanprovidetranslocative–

translaminaractivityonsuckinginsectsduringtheseedlingstage.

MaizeleafhoppersandmaizethripsarewidespreadbutirregularinQueensland,andcan

rapidlyre-infestcropsafterspraying,meaningmorethanonespraymayberequired. 15

7.4.3 Corn aphid Cornaphid(Rhopalosiphum maidis;Figure9)isthemostcommonaphidspeciesonmaize

andcanaffectanycropstage.Adultsandnymphssucksapandproducehoneydew.High







December 2014



numberscancauseplantstoturnyellowandappearunthrifty.Yieldlossmayoccuron

water-stressedplants.

Damageisgenerallytoolowtowarrantcontrol.Chemicalcontroloptionsaregenerally

notcost-effectiveandtheinsecticidesthatcontrolaphidsmaynegativelyaffectnatural

enemies.

Inspectatweeklyintervals.Predatorsofaphidsincludeladybirdlarvae,damselbugs,

bigeyedbugs,larvaeofgreenlacewingsandlarvaeofhoverflies.Waspparasitoids

mummifyandkillaphids.

Figure 9: Corn aphid. (Photo: DAFF Qld)

Aphidnumbershavebeenhighinbarleyandcanarycrops.Thesearepredominatelyoat

aphids,whichcanbefoundatthebaseoftheplantwheretheyarewellprotected;oat

aphidsdonotusuallyinfestsorghumandmaizeinAustraliabuthavebeenapestofmaize

intheUSA.Cornaphidsarepresentintheupperleavesandthewhorlofthebarleyand

havebeguntomigratetoearly-plantedmaizecrops.

BothCruiser®andGaucho®givegoodsuppressionfor2–3weeks,eventhoughcontrolof

aphidsisnotlistedoneitherseedtreatmentlabel.Cornaphidveryrarelyrequirescontrol

becausethenumberofdisruptivesprayshasbeendrasticallyreducedinthefarming

system.Aphidnumberscanbecomeveryhighinmoisture-stressedcrops,anditis

temptingtosprayinthesesituations;however,ifleftalone,beneficialinsectsusuallycontrol




December 2014



thesestickypests.Sprayingdisruptivechemicalsinthevegetativestagecancausegreater

problemslater,withaphidsandHelicoverpainfestingthecornsilksandtasselsinparticular.16

Build-upofaphidslaterinthecropcantransmitviruses,smotheringdevelopingcob

sheathsandcausingstickyresidueoverleaves,cobs.Rarelydoesitaffectyieldunless

transmittingparticularvirusesimpactingonmaize.

7.4.4 Podsucking or shield bugsTheseare:

• greenvegetablebugs(GVB)(Nezara viridula)(Figure10)

• redbandedshieldbug(Piezodorus hybneri)(Figure11)

Theyarewidespreadbutirregularpestsofmaizeduringsummer.Adultsandnymphsfeed

bypiercingandsuckingondevelopingcobs,andmayseverelydeformcobs.

Althoughchemicalcontrolmaybecost-effective,therearenothresholdcurrentlevelsfor

GVBinmaize.17Largenumberscancausediscolouredorabortedkernelsinthecob,

noticeableatharvest.Thismayaffectqualityforgritmarkets.

Figure 10: Green vegetable bugs, adults and nymphs. (Photo: DAFF Qld)

Figure 11: Redbanded shield bug. (Photo: DAFF Qld)










December 2014



7.4.5 LocustsLocusts(Figure12)aresporadicandpotentiallymajorpestsofmaize.Adultsandhoppers

chewirregularpiecesfromleavesandstemsandcancausecompletedefoliationovernight

athighpopulations.SpeciesfoundinmaizeincludeAustralianplaguelocusts,migratory

locusts,andspur-throatedlocusts.

TheAustralianPlagueLocustCommissionprovidesdetailsofhoppermigrations. 18

Figure 12: Locust. (Photo: DAFF Qld)

Whitefringed weevil

Whitefringedweevil(Naupactus leucoloma)larvaechewintolateralroots,causingdeath

andreducedvigour.Infestationsareusuallypatchy.Massemergenceofadultsoccursafter

raininNovember–January,anddamageisoftenworsewhentwohostcrops(e.g.maize,

peanuts,chickpea,lucerne)aregrownconsecutively. 19

7.4.6 Redshouldered leaf beetleRestrictedtocoastalareas,redshoulderedleafbeetle(Monolepta australis)(Figure13)and

caninfestatanystageofcropgrowth.

Swarmsofadultbeetlesmoveintoacropandfeedonfoliage,tassels,silksandthehusk

atthetopofthecob.Injurytosilksmayreduceseedset.Feedingexposesthecobsto

otherinsectsanddiseases.Infestationstendtobepatchy,sothoroughweeklychecking

isrequired.Controliswarrantedif95%ofplantsinanareaareinfestedand70%offlag

leavesareeaten.Chemicalcontroliscost-effectiveathighratesofinfestation.20













December 2014



Figure 13: Redshouldered leaf beetle. (Photo: DAFF Qld)

7.4.7 Swarming leaf beetlesSwarmingleafbeetles(Rhyparidaspp.)areaminor,irregularpestofmaizeinQueensland,

morefrequentinthenorth.Leafbeetlesarelikelytobepresentduringtheseedling

stage.Larvaefeedonroots,causingupto40%seedlingdeath.Therearenocurrent

recommendedmethodsofmonitoring,andeconomicinjurylevelshavenotbeen

established.Avoidplantingmaizeimmediatelyaftergrasspasture. 21

7.4.8 ArmywormsTheseare:

• commonarmyworm(Leucania convecta)

• day-feedingarmyworm(Spodoptera exempta)

Armyworms(Figure14)canoccurinlargenumbers,especiallywhengoodrainfollowsa

dryperiod.Duringtheday,thecommonarmywormsheltersinthethroatsofplantsorinthe

soilandemergesaftersunsettofeed.Outbreaksofday-feedingarmywormtypicallyoccur

fromlateDecembertoMarch,andlarvaeareactiveduringtheday.Youngplantsmaybe

defoliatedorkilled.Olderplantscanoutgrowdamagebutyieldmaybereduced.

Signsofdamageincludechewedleafmarginsandfaecalpelletsatthebaseofyoung

plantsorinthethroatsofolderplants.

Monitorduringseedlingandvegetativestages.Egglaysareoftenassociatedwithheavy

rainfall,socheckforlarvaeseveralweeksafterrainfallevents.Lookforlarvaeunderclodsof

soil,undervegetationandatthebaseofplants.Asaguide,controliswarrantedif,outofa

countof30plants,27areinfestedand>21haveatleast75%flag-leafloss.

Manychemicalswillcontrolarmywormsbuttheireffectivenessoftendependsongood

coverage,andcontrolmaybemoredifficultinhigh-yielding,thickcanopycrops,particularly

whenlarvaearerestingunderleaflitteratthebaseofplants.Becauselarvaearemost

activeatnight,sprayingintheafternoonoreveningmayproducethebestresults.







December 2014



Armywormlarvaeareattackedbyanumberofparasitoids,whichmayassistinreducingthe

intensityofoutbreaks,althoughtheyareunlikelytogivetimelycontrolifarmywormnumbers

arehigh.Predatorsincludegreencarabidbeetles,predatoryshieldbugsandperhaps

commonbrownearwigs.Viralandfungaldiseasesarerecordedascausingmortalityof

armyworms. 22

Commonarmywormcancauseseveredamagetowintercerealsandemergingsummer

crops.Generally,themothslayinbarleycropsinSeptemberandOctober.Thelarvaeprefer

lushcropsthatprovidegoodcoverandprotection.Iflarvaehavenotfinisheddevelopment

asthebarleyishaying-off,theycanmigratetonearbyfieldsofsummercrops.Barepatches

ontheedgesoffieldsadjoiningbarleyareagoodindicatorthatarmywormmaybepresent.

Lownumbersinbarleycancausehighlevelsofdamageinyoungsummercrops.Indry

years,armywormdamagecanbemistakenfordrypatchesinthefield. 23

Figure 14: Armyworm. (Photo: DAFF Qld)

7.5 Silking–tasseling-stage pests

7.5.1 Corn earwormCornearworm(Helicoverpa armigera)(Figure15)occursregularlyinmaize,butonly

occasionallydoesitwarrantcontrol.Femalemothslayeggsonthestem,leaves(both

sides),tassels,silksandhusksontheuppertwo-thirdsofplants.Caterpillarshatchingprior

tosilkingcauselittledamagetotasselsbutmaycausedamagewhenmigratingtocobs.

Larvaefromeggslaidonsilksorhusksmaycausesignificantdamage.However,themost

damagingscenarioiswhenlargelarvaethathavedevelopedinthevegetativecropmove

tothesilksandseverthemastheyfeed.Silkdamagereducespollinationandgrain-set.

Feedingdamagealsooccursonthetop1–3cmofthecobandmayresultinthepresence

ofmycotoxins.Damagetraditionallyoccursonthetop1–3cmofthecob,butthereare

increasingincidencesoflarvaedrillingintothesideofthecob.Thismaybeduetonew

varietieshavingsofterhuskcover.










December 2014



LeafdamagecanindicatethepresenceofHelicoverpalarvaeinvegetativecrops.

Armywormdamageissimilar.Parallelrowsofholesaresignsoffeedingonunopened

leaves.Helicoverpaarenotusuallyconsideredeconomictocontrol,exceptinhigh-value

seedmaize.Occasionally,grainmaizecropsareseverelydamagedbyHelicoverpa and

warrant treatment. Control of Helicoverpaatthisstagehasbecomearegularoccurrence

ontheLiverpoolPlains.Alongwithmanyothersummercrops,maizecropsatsilkingand

tasselinghavebecomeasignificantattractionforHelicoverpa armigera.

Chemicalcontrolshouldtargetsmallcaterpillars(upto7mm)andshouldbedirectedat

tasselsandemergingsilks.Nucleopolyhedrovirus(NPV)isanoptionforHelicoverpa control

withthebenefitofpreservingbeneficialinsectsthatwillcontributetoongoingsuppression

of Helicoverpaandotherpests.

Maizevarietieswithhusksextending50–80mmbeyondthetopofthecobandclosing

tightlyaroundthesilksrestricttheentryoflarvaeintothecob.Wateringduringdryweather

preventsthehusksfromloosening.

Maizecropsoftenhavehighlevelsofbeneficialinsects(predatorsandparasitoids)and

thesemaybeharmedbyinsecticideapplications.Thecombinedactionofnaturalenemies

(includingpredatorsofeggs,larvaeandpupae,parasitesofeggsandlarvae,andcaterpillar

diseases)canhaveasignificantimpact.Cultivationtoadepthof100mmdestroys

overwintering pupae.

ModeratetohighlevelsofeggparasitismbyTrichogrammaarecommon.Typically,thelevel

ofparasitismincreasesinlatercrops,andcanbeashighas90%.24Itmaybeeconomicto

investinaTrichogrammareleaseduringthelatevegetativestage.

Figure 15: Corn earworm. (Photo: DAFF Qld)







December 2014



7.6 Pests of the grainfill stage

7.6.1 Two-spotted miteTwo-spottedmite(Tetranychus urticae)isawidespreadbutirregularpestofmaizeduring

seed-filltomaturity.Mitesareusuallypresenttowardstheendofthecropcycleduringlate

summer–autumnandarefavouredbyhot,dryweather.Adultsandnymphspierceand

suckonlowerleafsurfaces,causingsilveringontheupperleafsurfaces.Finewebbing

onthelowerleafsurfaceindicatestheirpresence,andheavyinfestationswillresultinleaf

desiccation,leafdropandyieldloss.Ahandlenscanbeusedtoexaminelowerleavesfor

mites.Initialinfestationscanbepatchy.Nothresholdsareavailableformitesinmaizeand

controlisnotcost-effective.Theuseofbroad-spectruminsecticidesisassociatedwith

outbreaksofmites.Broad-spectruminsecticidesdisrupttheactivityofbeneficialinsects

(particularlythrips)thatsuppressmitepopulations.25Spidermitesareveryactiveon

LiverpoolPlainsandtheyhavetraditionallycausedsignificantdamage.

Controliswarranted.Thereisapermitforabamectinuseinfieldmaizeforcontrolofmites.

Theregiontendstouseiteveryyearinsomedistricts.

7.6.2 Yellow peach moth Yellowpeachmoth(Conogethes punctiferalis)isaminorandirregularpestofmaize.Eggs

arelaidduringsilking.Larvaetunnelintostemsorcobs,producingmassesofwebbingand

excretaatthetunnelentrance.Nochemicalcontrolsareavailable.Thelarvalhabitofmining

intostemsandcobsmakesinsecticideapplicationineffective,becauselarvaecannotbe

reachedwithintunnels. 26



i More information

KCharleston(2014)

Armywormsdefoliating

sorghum,milletand

cornontheDowns.The

Beatsheet.






http://thebeatsheet.com.au/crops/grains/sorghum/armyworms-defoliating-sorghum-millet-and-corn-on-the-downs/





Section 8 MAIZE - Nematode management


December 2014



SECTION8

Nematode management

Root-lesionnematodes(RLN)aremicroscopic,thread-likeanimalsthatliveinsoilandplant

roots.Plantrootsthataredamagedbynematodesareinefficientattakingupwaterand

nutrients,causingupto65%yieldlossinintolerantwheatvarieties.Pratylenchus thornei is

foundin~70%offieldsinthenortherngrainregion. 1

ResistanceandsusceptibilityofcropscandifferforeachRLNspecies,andmaizeis

moderatelysusceptibletobothP. thorneiandthesecondaryspecies,P. neglectus. 2

ManagementoftheP. thornei requires:

• growingtolerantwheatvarietiessothatyieldsaremaximised

• rotatingwithtwoormoresuccessiveresistantcropssuchassorghumsothat

populationsofthenematodesdecrease3

Inthenortherngrainregion,thepredominantRLN,P. thornei,coststhewheatindustry

AU$38millionannually.4

8.1 Nematode testing of soil

Itisimportanttohavepaddocksdiagnosedforplantparasiticnematodessothatoptimal

managementstrategiescanbeimplemented.Testingyourfarmwilltellyou:

• ifnematodesarepresentinyourfieldsandatwhatdensity

• whichspeciesarepresent

Itisimportanttoknowwhichspeciesarepresentbecausesomecrop-management

optionsarespecies-specific.Ifaparticularspeciesispresentinhighnumbers,immediate

decisionsmustbemadetoavoidlossesinthenextcroptobegrown.Withlownumbers,

itisimportanttotakedecisionstosafeguardfuturecrops.Learningthatapaddockisfree

1 KOwen,TClewett,JThompson(2014)Latestnematodesummerandwintercroprotationresults.GRDCUpdatePapers,7March2014,http://grdc.com.au/Research-and-Development/GRDC-Update-Papers/2014/03/Latest-nematode-summer-and-winter-crop-rotation-results

2 KOwen,JSheedy,NSeymour(2013)RootlesionnematodeinQueensland.SoilQualityPtyLtdFactSheet,http://www.soilquality.org.au/factsheets/root-lesion-nematode-in-queensland

3 KOwen,TClewett,JThompson(2014)Latestnematodesummerandwintercroprotationresults.GRDCUpdatePapers,7March2014,http://grdc.com.au/Research-and-Development/GRDC-Update-Papers/2014/03/Latest-nematode-summer-and-winter-crop-rotation-results

4 GMMurray,JPBrennan(2009)ThecurrentandpotentialcostsfromdiseasesofwheatinAustralia.GRDCReport, https://www.grdc.com.au/~/media/B4063ED6F63C4A968B3D7601E9E3FA38.pdf

i More information

GMMurray,JPBrennan

(2009)The current and

potentialcostsfrom

diseasesofwheatin

Australia. GRDC.

K Owen et al.Rootlesion

nematode—Queensland.

FactSheet.SoilQuality

PtyLtd.


http://grdc.com.au/Research-and-Development/GRDC-Update-Papers/2014/03/Latest-nematode-summer-and-winter-crop-rotation-results
















December 2014



ofthesenematodesisvaluableinformationbecausestepsmaybetakentoavoidfuture

contaminationofthatfield.5

Testingofsoilsamplestakeneitherbeforeacropissownorwhilethecropisintheground

providesvaluableinformation.

8.2 Effects of cropping history on nematode status

Root-lesionnematodenumbersbuildupsteadilyundersusceptiblecropsandcause

decreasingyieldsoverseveralyears.Theamountofdamagecausedwilldependon:

• thenumbersofnematodesinthesoilatsowing

• thetoleranceofthevarietyofthecropbeinggrown

• theenvironmentalconditions

Generally,apopulationdensityof2000RLN/kgsoilanywhereinthesoilprofilehasthe

potentialtoreducethegrainyieldofintolerantwheatvarieties.

AtolerantcropyieldswellwhenhighpopulationsofRLNarepresent(theoppositeis

intolerance).AresistantcropdoesnotallowRLNtoreproduceandincreaseinnumber(the

oppositeissusceptibility).

Growingresistantcropsisthemaintoolformanagingnematodes.Informationonthe

responsesofcropvarietiestoRLNisregularlyupdatedingrowerandDepartmentof

Agriculture,FisheriesandForestryQueenslandplantingguides.Notethatcropsand

varietieshavedifferentlevelsoftoleranceandresistancetoP. thornei and P. neglectus(see

Table 1).6

Table 1: Susceptibility and resistance of various crops to root-lesion nematodes7

RLN species Susceptible Intermediate Resistant

P. thornei Wheat,chickpea,fababean,barley,mungbean,navybean,soybean,cowpea

Canola,mustard,triticale,durumwheat,maize,sunflower

Canaryseed,lablab,linseed,oats,sorghum,millet,cotton,pigeonpea

P. neglectus Wheat,canola,chickpea,mustard,sorghum(grain),sorghum(forage)

Barley,oat,canaryseed,durumwheat,maize,navybean

Linseed,fieldpea,fababean,triticale,mungbean,soybean

For more information, download Managementofroot-lesionnematodesinthenorthern

grain region.



7 KJOwen,JSheedy,NSeymour(2013)RootlesionnematodeinQueensland.SoilQualityPtyLtdFactSheet.

i More information

http://www.

crownanalytical.com.au

PreDicta B. SARDI

DiagnosticServices.

Root-lesionnematodes—

management of root-

lesionnematodesinthe

northerngrainregion.

QPIF.



















December 2014



8.3 Using rotations including maize to manage nematodes

SummercropshaveanimportantroleinmanagementofRLN.Researchshowsthatwhen

P. thorneiispresentinhighnumbers,twoormoreresistantcropsinsequenceareneeded

toreducepopulationstolowenoughlevelstoavoidyieldlossinthefollowingintolerant,

susceptiblewheatcrops.8

8.3.1 Key points:• Oneresistantcropinsequencemaynotbeenoughtodecreasedamagingpopulations

of P. thornei.

• P. thornei survivedafterasequenceoffiveresistantcrops,butinverylowpopulations.

• Management of P. thornei bygrowingseveralresistantcropsissuccessful,and

populationscanbereducedtoverylowlevels.However,on-goingvigilancebytesting

soilfornematodesisessentialwhensusceptiblecropsareplanted.

FormoreinformationontheeffectofsummercroprotationsonRLNinwintercrops,see

GRDC GrowNotes Wheat, Section 8. Nematode control.

8 KOwen,TClewett,JThompson(2013)Summercropdecisionsandrootlesionnematodes.GRDCUpdatePapers16July2013,http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/07/Summer-crop-decisions-and-root-lesion-nematodes

i More information

K Owen et al.(2013)

Summercropdecisions

androotlesion

nematodes.GRDC

UpdatePapers.









Section 9 MAIZE - Diseases


December 2014



SECTION9

Diseases

DiseasesaffectingmaizegrowninAustraliaincludecobrots,stalkandrootrots,viruses,

smuts,leafblightsandleafrusts.

Theincidenceandseverityofdiseaseoutbreaksdependonseveralfactorsincluding

management(water,nutritionandcrophygiene),varietalgeneticsandhybridvigour,

location,plantingdate,seasonalextremes,infestationbyinsects,culturalpractices,

populationsandhuskcovergivingcobprotection.

MostofthehybridsreleasedinAustraliahaveanacceptablelevelofdiseaseresistance. 1

Manydiseasesinmaizecanbeovercomebyselectingresistanthybrids.Additionally,good

farmhygiene,includingwashingdownequipmentandcontrollingweedsandvolunteers,

canminimisediseasespreadfromcroptocropandfromseasontoseason.Diseasesare

importanttomaizeproductionnotonlybecauseoftheirpotentialtoreduceyield,butalso

becausethemarketingofgraincanbeseverelyrestrictedbythemerepresenceofdisease,

addingfurthertotheneedtochoosehybridscarefully.Formoreinformationonresistancein

hybrids,seeGrowNotesMaizeSection2.Pre-planting. 2

Selecthybridsthathaveresistancetodiseasesprevalentinyourarea.Onthenorthcoastof

NewSouthWales(NSW),hybridsneedgoodresistancetoturcicaleafblight(alsoknownas

northernleafblight,causedbyExserohilum turcica)andMaize dwarf mosaic virus(MDMV).

Inmanyareas,Fusariumkernelrot(causedbyFusariumspp.)hasresultedinsignificant

yieldlossesandqualityissuesingrainsamples.ItcanalsobeahostforFusariumhead

blightsinwintercereals.

Commercialhybridsarerelativelytoleranttoboilsmut(causedbythefungusUstilago

zeae),andtodatethediseasehasnotcausedsignificantyieldlosses,exceptwherecrops

havebeenmoisturestressedjustpriortosilking;however,thepathogenisair-borneand

itisdifficulttobreedresistancetoboilsmut.Incoastaldistricts,selecthybridswithtight

huskcovertohelppreventweevilandHelicoverpadamageandalsotosignificantlyreduce

cobrotsandweatherdamage.Ininlandregions,loosehuskcoverisoftenconsideredan

advantagebecauseitencouragesrapiddrydown. 3


2 NMoore,LSerafin,LJenkins(2014)Summercropproductionguide.NSWDPIManagementGuide.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/agriculture/broadacre/guides/summer-crop-production-guide


i More information

Maizedisorders:theute

guide. GRDC.


growers’workshop.

Pioneer Hi-Bred.

A Robertsonet al. Corn

diseases.IowaState

University.

Corn fieldguide.

2nd edn. Iowa State

University.








http://grdc.com.au/Resources/Bookshop/2006/02/Maize-Disorders-The-Ute-Guide

http://grdc.com.au/Resources/Bookshop/2006/02/Maize-Disorders-The-Ute-Guide




https://store.extension.iastate.edu/Product/Corn-Diseases



https://store.extension.iastate.edu/Product/Corn-Field-Guide-2nd-Edition





December 2014



9.1 Diseases of a developing and mature maize plant

Sincethe1930swhenmaizewasconvertedfromanopenpollinatedspeciestoahybrid,

diseaseresistancehasbeenahighpriorityforbreedersaroundtheworld.Mostofthe

maizediseasesinAustraliaareinfluencedbyseasonalconditionscausingstressonthe

plant,suchasveryhotspellsduringgrainfill,continuedcloudyweather,build-upofvirus-

spreadinginsectsandhighhumidity.

Aswithnutrientdeficiencies,diseasesareoftenhardtopositivelyidentifyinthefield.

Samplesmayneedtobesenttoaplantpathologistforidentification,particularlyforthecob

andstalkrots,andviruses.

Nearlyallcasesofstalkandcobrotscanbetracedbacktoaperiodofstressatacrucial

stageofdevelopment,forexample,avitalwateringbeingdelayedbyacoupleofdays.

9.1.1 Seed rots and seedling blights Germinatingmaizeseedmaybeattackedbyanumberofsoil-borneorseed-bornefungi

thatcauseseedrotsandseedlingblights.Thesediseasesareprevalentinpoorlydrained,

excessivelycompactedorcold(<10–13°C)andwetsoils.Diseaseseverityisaffectedby

plantingdepth,soiltype,ageandqualityofseed,mechanicalinjurytothepericarpand

geneticresistancetoinfection.Sweetcornismoresusceptiblethanfieldmaize.Themain

fungiinvolvedare:Pythiumspp.,therottedareamaybedarkwithsporangiaandoospores

inthetissues;Diplodiaspp.,whitish-grey;Fusariumspp.,whitetopink;andPenicillium

spp.,bluishmyceliumandmassesofspores.

9.1.2 Stalk and root rot diseasesStalkrotsarediseasesthataremostcommonlyexpressedasplantsreachmaturity.Maize

stalkrot(Figure1)tendstobeacomplexofseveraldisease-causingfungiandsometimes

bacteria;seldomwillonlyonecasualorganismbeisolatedandidentified.Plantswithrotted

stalksalmostalwayshaverottedrootsaswell.Usually,thesamecasualorganismsare

involved.Visualidentificationisverydifficult;typically,wiltingisthefirstsignofstalkrotina

field.Inafewdays,leavesturna‘frosted’grey,earsdroopandtheouterrindofthelower

stalkturnsbrown.Fieldswherestalkrotisdevelopingshouldbeharvestedearlytoreduce

grainlosses.4







December 2014



Figure 1: Bacterial stalk rot. (Photo: Pacific Seeds)

Fusarium stalk rot (caused by Fusarium verticillioides [Gibberella fujikuroi] and other Fusarium species)

AlthoughFusariumstalkrotiscommoninmanyofthemaize-growingareasofAustralia,it

tendstobemoresevereinwarm,dryregions.OntheAthertonTablelands,itoftenoccurs

inthefirstmaizecropafteralengthypasturephase.Fusariumspeciesandotherfungican

alsocauseseedlingblightbutthisisuncommonbecauseofimprovedseedproductionand

handling,andplantingtechniques.

Infectedseedlingsareusuallystuntedandhavepalegreenorpurpleleavesandpoorroots.

SymptomsofFusariumstalkrotinmatureplantsaredifficulttodistinguishfromthoseof

otherstalkrots,buttheinternaltissuesofaffectedstalksareusuallyreddish-brownand

rotted.Thediscolorationmayalsobeseenonthesurfaceofthestalksnearnodes.Stalks

areweakandlodgeeasily.




December 2014



Goodagriculturalpractices,includingcroprotation,correctplantdensitiesandthe

minimisationofstress,assistinreducingFusariumstalkrot.Resistanthybridsshouldbe

usedtomanagethisdisease. 5

Gibberella stalk rot (caused by Gibberella zeae; Fusarium graminearum)

Thisfungaldiseaseisfavouredbymoistconditions.ItismorecommonontheAtherton

TablelandsandincoastalandinlandnorthernNSW,whereitcancauseseriousyieldloss.

Thediseaseismuchlessseriousinotherregions,includingsouthernQueensland.Itis

commonwheremaizemonocultureispracticed.

Thesurfacesofinfectedstalksareoftenreddishbrown,particularlyaroundthenodes,and

thetissuesinternallyarered-pink.Stalksareweakandbreakeasily,resultinginlodgingand

plantdeath.Laterintheseason,small,round,bluishblackfruitingbodiesmaybefound

aroundthenodesofdeadstalks.

SimilartotheFusarium speciesthatcauseFusariumstalkrot,F. graminearum survives

ininfectedresiduesandcansystemicallyinfectplants.Thefunguscausesheadblightof

wintercerealsandhasbeenaprobleminsomeyearsontheLiverpoolPlainsofNSWin

maize–wheatrotations.

Usecroprotation(avoidingmaize–wintercerealrotations),goodagronomicpracticesto

minimisestress,and/orresistantmaizehybridstocombatthisdisease. 6Decomposing

maizeresiduesignificantlyreducesthesurvivalandspreadofthepathogentosurrounding

cereals.

9.1.3 Ear and kernel rotsTheserotscanaffectearsorkernels,reducingtestweightandgrainquality.Somerotsare

responsiblefordevelopmentofmycotoxinsthatmaycontaminategrain.Rottingobserved

inthefieldisoftenduetoacomplexofcasualorganisms,notjustone.Mostearrotsare

favouredbylateseasonhumidity.

Infectionsareincreasedbycobdamagefrombirdsorinsectsandbystalklodging,which

allowsearstocontactthesoil.

Growthstagesduringwhichsymptomsgenerallyappearare:

• stageI,emergencetokneehigh

• stageII,fromkneehightotasselling

• stageIII,fromtassellingtomaturity

5 DAFF(2012)Diseasesaffectingmaize.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/diseases



http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/diseases






December 2014



Fusarium cob rot or ear rot (Fusarium verticillioides and other Fusarium species)

Fusariumcobrotisfavouredbywarm,dryweatheratorafterfloweringandcanoccurinall

maize-growingareasofAustralia.Fusarium verticillioides,themainpathogen,producesthe

mycotoxinfumonosin,whichistoxictolivestock,particularlyhorses.

Individualorgroupsofinfectedkernelsarescatteredatrandomonthecobs,butinsevere

cases,theentirecobcanbeaffected.Whitishpinklavenderfungalgrowthoccursonand

betweenthekernels,oftenatthetipofthecobastheresultofinsectdamage.Individual

kernelsmayalsoexhibita‘starburst’symptom,wherebywhitestreaksradiatefromthe

pointofattachment.

TheFusarium speciesoverwinterininfectedresidues.Duringthegrowingseason,airborne

sporesinfectthesilksatflowering.Theyarealsoknowntobesystemicinmaizeplantsand

growrapidlywhenplantsarestressed.

ThepracticesoutlinedaboveforFusariumstalkrot,aswellasthemanagementofinsect

pestsandproperstorageofkernels,reducetherisksofmycotoxincontamination.Use

resistanthybridswhereavailable. 7

Gibberella cob rot, ear rot or pink ear rot (caused by Gibberella zeae; Fusarium graminearum)

Gibberellacobrotisfavouredbycool,moistconditionsatflowering.Therefore,likethestalk

rotphase,itismorecommoninwetter,coolergrowingregions.Severalmycotoxinsare

producedbyF. graminearum,includingzearalenoneandthetrichothecenegroup,which

areharmfultoawiderangeoflivestock,especiallypigs.Maizemonoculture,maize–winter

cerealrotationsandplantstressduringgrainfillarefactorsinthedisease.

Themostcommonsymptomisareddishpinkorwhitishpinkfungalgrowththatappears

atthetipofthecobandgrowsdown.Huskstendtobindtothekernelsandtheremay

beblackfruitingbodiesonexternalhuskleaves.Infectionoccursfromwindbornespores,

whichgrowdownthesilksatflowering.

Theuseofgoodagronomicpractices,resistanthybrids,promptharvestingandproper

storageminimisestherisk. 8

Diplodia cob rot or ear rot (caused by Diplodia spp.)

MostofthespeciesthatcauseDiplodiacobrotarealsocapableofcausingseedlingdeath,

stalkrot,and/orleafspot;however,cobrotisthemostsignificantdisease.Wetweather

favoursinfectionofcobsandleaves.

Ifinfectionoccursafterflowering,thehuskscoveringthecobsarebleached.Cobsare

usuallyshrunken,lighterthannormalandcoveredinawhite-greyfungalgrowth.Black










December 2014



fruitingbodies(smallerthanthefruitingbodiesofGibberella spp.) developinthehusksand

cobstowardstheendofthegrowingseason.

Diplodia speciessurviveininfectedresidues,andsporesproducedinfruitingbodiesare

splashedonthesilk,whichremainsusceptibletoinfectionastheyaredrying.

Theonlyknownmanagementoptionstohastenresiduebreakdownarecroprotationand

agronomicpractices. 9

9.1.4 Blights

Turcica leaf blight or turcicum leaf blight (caused by Exserohilum turcicum)

Turcicaleafblightcanoccurinallgrowingregions.Itisfavouredbywarmweatherwhen

leavesarewetforextendedperiodsfromdeworrainfall.Underweatherconditionsthat

areconducive,itcancausesignificantyieldlossesinsusceptiblehybrids.Itisofparticular

concerninareasexperiencinghighrainfall,humidityandtemperatures,suchascoastal

NSW,wherethediseaseispresentmostseasons.Specifically,14h(non-consecutive)of

temperatures≥20°Cand1hofleafwetnessarenecessaryforinfectiontooccur.Dew

conditionsalsopromotediseasegrowth.Late-sowncropsarealsosusceptibletoinfection.

Inoculumoverwintersonstubbleandmaizevolunteers,aswellassorghum,andthisshould

beaccountedforinrotationplans.Inoculumisdispersedbywindandrainsplash.

Long,spindle-shaped,greyishgreentotan,water-soakedspots(upto150mmlongand

usually<20mmwide)developonleavesandlaterturnlightpurplishbrownorgrey.As

thelesionsdryouttheybecomeblackinthecentreasmassesofsporesareproduced

bythefungus.Thelesionsarenotconfinedbytheleafveins.Asthedisease,progresses

thelesionsmaycoalesce,causinglargeareasofleaftowitheranddie.Afterflowering,the

diseasecandeveloprapidly,resultinginblightingofinfectedleaves.

Thefungussurvivesonvolunteersandmaizeresidues,anditssporesarespreadoverlong

distancesbywind.

Leafblightcanhavedeleteriouseffectsoncropyield.Wheresignificantleaftissueis

destroyed,onlysmallcobsareproduced.

Resistantvarieties,correctsowingtime,croprotation,regularmonitoring,andremovalof

stubbleandhostswillreduceriskofdisease.Donotpracticemaizemonoculture.Eliminate

volunteermaize.Earlyplantingcanreducetheriskofthisdisease.Chemicalcontroloptions

arealsoavailable,inwhichleafcoverageisessential,,becauseuntreatedleafareais

susceptibletoblight.10










December 2014



Maydis leaf blight (caused by Bipolaris maydis)

Infectionanddiseasedevelopmentarefavouredbywarm,showery,humidweather.

Althoughitcanoccurinallmaizegrowingareas,maydisleafblightismorecommoninthe

tropics.

Symptomscanvarydependingonthehybrid.Spotsrangefromtan,elongatedspotsup

to40mmlongand6mmwidewithparallelsides,totan,spindle-shapedorellipticalspots

upto25mmlongand12mmwide.Spotsoftenhavedarkred-brownmarginsand/ora

narrowyellowhalo.Thisfunguscanbeseedborneandcauseseedlingrot.

Thefungussurvivesondiseasedresidues,volunteermaizeandgrasses.

Resistanthybridsshouldbeplantedtocombatthisdisease. 11

9.2 Rusts

AlthoughrustoccursacrossNSWandispresentinmostseasons,severeoutbreaksare

uncommon,andresultanteconomiclossislow.

Rustappearsonleavesinitiallyassmallreddishbrownpustulesto2mmlonginscattered

groups,usuallyfromtassellingonwards.Pustuleswilllightenwithmaturityassurrounding

leaftissuedies.Withsevereinfection,leaveswillwitheranddie.Seedlinginfectionmayalso

occur,leadingtostuntinganddefoliation.

Humidconditionscoupledwithmildtemperaturesfavourdiseasedevelopmentin

susceptiblehybrids.Lateplantingstendtobeatgreatestrisk.Maizevolunteers,stubble

andsomewintercropshostrust;however,inoculumisalsowinddispersed.

Appropriatevarietalselection,correctsowingtime,croprotationsandcontrolofhosts

assistinpreventativemanagementofrust. 12

9.2.1 Common rust (caused by Puccinia sorghi)Thisrustisfoundinmostmaize-growingareasbutismorecommonintemperateand

subtropicalregions.Moderatetemperatures(16–25°C),humidweatherandleafwetness

durationsofatleast6hfromrainordewfavourinfectionanddiseasedevelopment.

Thediseaseisrecognisedbytheabundantoval-elongate,red-brownpustulesupto2

mmlong,whicheruptthroughbothleafsurfacesinscatteredgroups.Thisdistinguishes

commonrustfrompolysorarust(seebelow),whichhaslittledevelopmentofrustpustules

onthelowerleafsurface.Thepustulescontainnumerouspowderysporesthatcanbe

spreadlongdistancesbywind.

Commonrustsurvivesbetweenseasonsonlyonlivingmaizeplants.










December 2014



Theonlypracticalcontrolmeasureistoplantresistanthybrids.Sweetmaizehybridstendto

bemostsusceptible. 13

9.2.2 Polysora rust or tropical rust or southern maize rust (caused by Puccinia polysora)

Polysorarustisfavouredbywarm,wetweatherandis,therefore,adiseaseoftropical

regions.Similartocommonrust,itneedsalongperiodofleafwetnessforinfection.

Severelyaffectedleavescandie,whichresultsinlighterthannormalears.

Smallred-brownororangepustulesdevelopevenlyovertheupperleafsurfaces,andlarger

elongatedpustulesmayalsodeveloponthemidribs,earhusksandtassels.Polysorarust

survivesbetweenseasonsonlyonlivingmaizeplants. 14

9.3 Smuts

9.3.1 Boil smut or common smut (caused by Ustilago zeae, formerly known as U. maydis)

Boilsmutoccursinmostproductionareasbutisoftensporadicandminor.

Allabovegroundpartsoftheplantcanbeinfected,butparticularlytheactivelygrowing

tissuesoncobs,tasselsandstems.Blistersorgallsdevelop,initiallywithathinwhite

membraneandlatercontainingblackpowderyspores.Maturegallscangrowaslargeas

20cmindiameter.(Thefungusformsgallsonallabovegroundpartsofmaizespecies,

andisknowninMexicoasthefooddelicacyhuitlacoche;itiseaten,usuallyasafilling,in

quesadillasandothertortilla-basedfoods,andsoups.)

Sporescanbespreadbywind,seed,clothesorfarmmachineryandcansurviveinthesoil

formanyyears.Thesporesgerminateundertherightconditionsandproduceanothertype

ofsporethatistransportedtotheplantviatheair.

Mosthybridshaveareasonablelevelofresistancetoboilsmut.However,itisimportantto

practicegoodcrophygieneandensurethatseedistreatedwitharegisteredfungicide. 15

Youngseedlingsbecomeswollenanddistorted.Infectionsduringthevegetativestageof

growthareexpressedasgalls(boils)onthestems,leafaxilsandleaves,whichareinitially

palegreenandbecomewhiteandfullofblackpowderysporesatmaturity.Inmoremature

plants,boilsforminkernels,causingthemtoenlargeanddeform,distortingthecob.

Thefungusdevelopsattemperatures>25°Candindryconditions;however,itspreads

inrainorhighhumidity.Highlevelsofsoilnitrogenalsofavourthefungus,andphysical

damageincurredfrommechanicaldisturbance,forexample,canincreaseinfection.Spores





http://en.wikipedia.org/wiki/Mexico

http://en.wikipedia.org/wiki/Quesadilla









December 2014



aredispersedbywindandthroughcontactsources.Inoculummayremainviableinsoilfor

manyyears.Althoughlossesarenotusuallysignificant,occasionallyyieldlossissevere.

Varietalselectionmayassistinreducingriskofinfection;however,anintegrated

managementprogramisnecessaryforgreatereffectiveness.Thisinvolves:cleaning

machineryandbootstoreducecontamination,regularlyinspectingcrops,removing

infectedplants,minimisingplantinjuries,carefulrotationsandapplyingseedtreatments.

Vitavax®200FFistheonlyregisteredchemicalseedtreatmentavailable.Burningstubble

mayalsobeeffectiveinreducinginoculumthatmayoverwinter.16

Boilsmutlooksbadwhenfoundinacrop,butitaffectsonlyaverysmallpercentage

ofmaizecrops.Itisnotpoisonous;however,somestatessuchasTasmaniaaskfor

certificationoffreedomofboilsmutinacrop.Thisisnearlyimpossibletocertifybecause,

oncethecropisharvested,itisdifficulttopickupinthegrain,anditcanbefoundinmost

crops.Inmostcases,themaizeispartofafeedration,andsoitisnotathreattobe

spreadthroughplanting.

9.3.2 Head smut (caused by Sporisorium reilianum)Thisfunguscausesthereplacementofpartorallofthecob,andoftenthetassel,with

blackmassesofpowderyspores.Atfirst,thesemassesarecoveredbyawhitemembrane,

whichlaterbursts.Leafystructuresmayreplacethereproductivetissues.Badlyaffected

plantsmaybestuntedandhaveprofusetillering.

Infectioninitiallyoccurswhensporesinthesoilgerminateandinfectseedlings.Thefungus

thengrowsthroughtheplant,ultimatelyinvadingthedevelopingcobsandtassels.Infection

isfavouredbysoilwithlowmoisturelevelsandtemperaturesof21–28°C.

Plantresistanthybridsandavoidearlyplantingofsusceptiblevarieties. 17

9.4 Wallaby ear

Affectedplantsareoftenstunted,andtheirleavesaredarkgreenorgreen-blue,have

thickenedveins,andareheldatanacute(upright)angle.Thedisorderismorecommon

insubtropicalcoastalareas,whereitcanseverelyaffectyield.Itoccurswhenatoxinis

injectedintotheplantbythejassid(leafhopper)Cicadulina bimaculatawhilefeeding. 18

Theconditionistheresultoftheplant’sreactiontothetoxininjectedbythejassid.This

particularspeciesmostlyoccursinnortherncoastalareasofNSW,wheresignificant

damagemayresult.However,theconditionisnotofalargescaleinmostyears.

Wallabyearexpressesasshortenedleavesheldupright,withveinsonthelowerleafsurface

markedlythickenedandoftendarkgreenorblue-greenincolour.




i More information

CBeckingham,A

Watson(2006)Boilsmut

of corn. DPI PrimeFact

247.

Corn smut.Wikipedia.








http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0010/107929/boil-smut-of-corn.pdf




http://en.wikipedia.org/wiki/Corn_smut



December 2014



Seasonalconditionsthatpromotetheproliferationofjassidpopulationswillseeagreater

incidenceofthecondition.

TherearenoinsecticidesregisteredforthecontrolofjassidsinmaizeinNSW.19

9.5 Viruses

9.5.1 Johnson grass mosaic virusJohnson grass mosaic virusisadiseaseoftemperateandsubtropicalareas,andcanbea

seriousprobleminsouthernQueensland.

Manymaizehybridshavegoodresistance,althoughsweetmaizevarieties,especially

supersweettypes,arehighlysusceptibleifplantedlateintheseason.

Symptomsareeitheraring-spotpatternoramosaicoflightanddarkgreenpatchesonthe

leaves.Plantsofhighlysusceptiblehybridscanhaveyellowleaves,maybesmallandsuffer

considerableyieldloss.

ThevirussurvivesinJohnsongrassandinoldorratoonforageandgrainsorghumcrops

betweenseasons.Itisspreadbyaphidsandtransmittedafterashortfeedingtime.

Plantingresistanthybridsisthemaincontrolmeasureforthisdisease,althoughsweet

maizeishighlysusceptible.ControlJohnsongrassonyourfarm. 20

9.5.2 Maize dwarf mosaic virus Maize dwarf mosaic virusappearsasstripingandmottlingofleaves,whichmaybe

confusedwithzincdeficiencysymptoms.Sometimestherearedarkgreen‘islands’

surroundedbylightercolouredrings.Anoverallyellowingofplantsiscommonandsome

maybecomestunted.Thevirusmaycausehuskstogape,whichcanresultinhigher

incidence of grain rot.

Thevirusisspreadfromdiseasedplantstohealthyplantsbyseveralspeciesofaphids.

SorghumandgrassessuchasJohnsongrassarealsohoststhatcontributetothe

overwinteringofdiseaseandincreasetheriskofinfectioninlate-plantedcrops.Ifinfection

occursatanearlystage,stuntingandsubsequentreductionsinyieldandgrainqualitycan

result.

Therearemoderatelyresistantvarietiesavailabletoreduceriskofinfection;however,itis

alsoimportanttomanagediseaseagronomicallybycontrollingvolunteerweedsandmaize

plantsandmonitoringcropsregularly. 21




i More information

Diseasesaffectingmaize.

DAFFQueensland.

Photogalleryofdiseases

affecting maize. DAFF

Queensland.

PRHarvey et al.(2006)

Emergingsoil-borne

constraintstoirrigated

maize:aPythium–

Fusariumrootdisease

complex.

AWatson et al.(2006)

Fusariumspp.associated

withearrotofmaize

inthe Murrumbidgee

Irrigation Area of New

SouthWales.










http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/disease-photos



http://www.maizeaustralia.com.au/events_files/Emerging biological constraints - pythium-fusarium - P Harvey.pdf






http://www.maizeaustralia.com.au/events_files/Poster Watson.pdf








December 2014



9.6 Rots of stored grain

Ifgrainisstoredat15–20%moistureand21–32°Ctemperature,thereisahigherprobability

ofgrainrotsdeveloping.Ontheotherhand,grainmoistureof<15%andtemperatures

<10°Cposelittleriskofdamagefromfungi.

Storagerotsarecausedbymanyfungi,butmainlyspeciesofAspergillus and Penicillium.

RupturedkernelswillsometimesattractsomespeciesofFusarium,anotherreasontoset

theheaderupcorrectlytoavoidbrokenordamagedgrain.

Invasionofwholekernelsinstorageresultsindiscoloration,heating,cakingandmustiness.

Onestoragerot,knownas‘blue-eye’ischaracterisedbyabluishgreengerm. 22

9.7 Mycotoxins and mycotoxicoses

Mycotoxinsarefungalmetabolitesthataretoxicwhenconsumedbyanimalsorhumans.

Mycotoxinscanaccumulateinmaturingmaizestandinginthepaddockoringrainduring

transportationandstorageunderconditionsofmoisture,humidityandtemperatures

favorableforgrowthofthetoxin-producingfungusorfungi.

Diseasesinanimalsandhumansresultingfromtheconsumptionofmycotoxinsaretermed

mycotoxicoses.

Theeffectsrangefromlossofappetite,feedrefusalanddecreasedfeedefficiencyto

mortalityindomesticanimals.Thereisalsoelevatedbodytemperatureanddecreasedfeed

intake.

Threegeneraoffungi—Aspergillus, Penicillium and Fusarium—aremostfrequentlyinvolved

incasesofmycotoxincontaminationinmaize(Table1).Aspergillus flavusproduces

aflatoxinsinmaizestartingatamoisturecontentof~18%andattemperaturesof12–42°C

(optimum25–32°C).

Formoredetailsonmycotoxins,visitMaizeAssociationofAustraliaandlookforthefindings

andrecommendationsbyJohnKopinskiandBarryBlaneyinManagingMycotoxinsin

Maize. 23



i More information



guide. NSW DPI

Management Guide.

AWatson(2007)

Fusariumcobrotofcorn.

NSW DPI Primefact 243.


http://www.maizeaustralia.com.au

http://www.maizeaustralia.com.au/mycotoxin_files/Managing Mycotoxins in Maize- Options when feeding animals.pdf

http://www.maizeaustralia.com.au/mycotoxin_files/Managing Mycotoxins in Maize- Options when feeding animals.pdf









http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0016/113623/fusarium-cob-rot-of-corn.pdf





December 2014



Table 1: Cob and stalk rots associated with mycotoxins of concern in NSW maize crops

Disease symptoms Disease infection and spread Mycotoxin characteristics Conditions favouring mycotoxin development

Good agricultural practice to prevent grain contamination

Aspergilluscobrot

Greenish–greymouldgrowthaffectingasmallproportionofkernelsinasmallnumberofcobs.Infectionstendtobelimitedtoasmallsectionofthefield,forexampleanareaofshallowersoilwheremoisturestressoccursbetweenirrigations.

Aspergillusspp.(mostcommonlyA.flavus)enterthecropaswind–blownsporesthatarehighlyresistanttodesiccation.Fungiaccesstothedevelopingkernelsviathesilksandsitesofphysicaldamagetotheearfrominsectsorbirds.Oncefungalgrowthhasbegunitcontinuesuntilgrainmoisturecontent(MC)fallsbelow14%.Aspergillusspp.aretolerantofhotterconditionsthanmanyotherfungaldiseases(A.lavus12–43°C,optimumis30°C).

A. flavusisalsoknownasa‘storagefungus’asitgrowsatlowmoisturecontents.Temperaturefluctuationsingrainstoredslightlyabove14%MCwillcausesmallamountsof‘availablemoisture’tomigrateintopockets.Thiscreatesopportunitiesforthefungitogrow.Initiallyitwillgrowinjustthefewinfectedkernels,butasmoistureisreleasedfromthegrainbythefungalgrowththerateofnewinfectionincreases.Theprocessisacceleratedbystorageinsects.

Aflatoxins A. parasiticusproducesaflatoxinsB1andB2whileA. flavusproducesB1,B2,G1andG2.AflatoxinB1isoneofthemostpotentlivercarcinogensknown.Aflatoxinscanalsocauseacuteeffectswheninjestedbyhumansoranimalsinhighdoses.

NonaturalcasesofhumandiseasecausedbyaflatoxinhavebeenrecordedinAustralia,butlivestockhaveoccasionallybeenpoisoned.

Ochratoxin A ProducedbyA. ochraceus and A. niger.Causeskidneydamageandimmunosupressioninanimalsandisclassifiedasapossiblehumancarcinogen.

Thecriticalperiodforaflatoxinproductionbegins20daysafteranthesis.Atthistimeaflatoxindevelopmentisfavouredif;averageday/nighttemperaturesexceed27°Candapproach32°C,thereispersistenthighhumiditythroughgrainmaturationandtheeardriesprematurely.

Instoredgrain,veryhighconcentrationscanquicklydevelopifthemoisturecontentis16–20%.

LittleisknownaboutfactorsromotingochratoxinA.ItsoccurenceismuchlesscommoninAustraliathanaflatoxins.UntilmoreisknownitisreasonabletoassumethatmanagingaflatoxinswillalsominimisetheriskofocharatoxinA.

Pre–plant Selecthybridsthatareadaptedforthelocalconditions.

Before planting, calculatewaterbudgetstomatchtheareaofcroptotheavailablewater allocation.

Donotstresscropsbyincreasingtheirrigationinterval,particularlyduringgrainfill.

Planting Chooseplantingtimesthatminimiseexposuretohottemperaturesduringkernelformation.

Growing Wherehotconditionscannot be avoided duringgrainfill,monitorcropwateruse,reducingirrigationintervalsasrequired.

Adjustirrigationacrossthefieldtocounterareasofsoilwithlowerwaterholdingcapacity.

Closelymonitorheliothisandarmyworm.

Harvest Avoidharvestdelays.Considerharvestingatahighermoisturecontentandartificiallydryinggrainbelow14%forstorage.

Atharvestminimiselightweightmaterialinthesample.DamagedkernelsorpoorlyfilledkernelsaremorelikelytocarryAspergillusspp.and Fusariumspp.

Harvestareasofthefieldaffectedbymoisturestressseparately.

Storage Storegrainat12%MC,maintainconstantstoragetemperatureandcontrolinsectpests.

Fusariumcob

andstalkro

ts

Powderyorcottonywhitish–pinkfungalgrowthonstalknodes,ininternalstalktissueandonclustersofkernelsscatteredrandomlyovertheear.Kernelsbecome tan or brown andoftenappearwitha‘starbust’patternoffinecracks–producedbysuddencontractionandexpansionofthegrainpericarp(skin).

Fusariumspp.(commonlyF. verticilliodes)overwintersincropresiduesandspreadsbywind–blownspores.Infectionsaresystemic,alsopossibleviaseedtransmission.Infectionbecomespathogenicwhendroughtstressbeforeandduringsilkingisfollowedbywarm,wetconditionsduringgrainfill(causingsuddenchangeinthegrainpericarp).Infectiontendstobemoresevereindenseplantstandsandcropsdamagedbyinsectattack.Higherriskofstalkinfectionisassociatedwithmaizefollowingapasturephaseintherotation. Fusariumspp.requiremoisturecontentsabove18.4%forgrowthinkernels.

Fumonisins F. verticilliodesispresumedtobethemainsourceoffumonisinsinAustralia,howeverseveralotherFusariumspp.capableoffumonisinproductioninmaize.Fumonisinsareparticularlytoxictohorsescausingliquefactionofthebrain.Inpigstheycausepulmonaryoedema.Cattle,sheepandpoultryarefairlyresistant.Theirroleinhumandiseasesisstillbeinginvestigatedbuttheyhavebeenassociatedwithoesophagealcancer.

Fumonisinproductionoccurswhentheplant’sdefencesandtheactivityofabeneficialfungus,Acremonium zeae,areimpairedbymoisturestressorphysicaldamage.Fumonisinismorelikelytobeproducedwheregrainendospermhasbeenexposed.

DuetothehighmoistureandhumidityrequirementsofFusarium spp.,developmentoffumonisinsinstoredgrainishighlyunlikely.

Gibberellacob

andstalkro

ts

Rottingstalksexhibitreddish–pinkdiscolourationofinternaltissues.Hard,black,globularfruitingbodies(perithecia)maybefoundontheexteriorsurfacesofthestalksandexteriorhusksofinfectedcobs.Infectedcobsfillwithreddish–pinktodarkpurplefungalrotextendingfromthetipoftheeartowardsthebase.Huskstendtobindtothekernels.

Fusariumgraminearum(formerlyGibberella zeae)survivesintheresiduesofmanyfieldcrops–wheat,maize,rice,sorghumandpasturegrasses.Releaseofascosporesthatinitiateinfectionistriggeredbycool,wet,humidconditions,fromsilkingthroughgrain maturation. Favourable conditionsaremorecommoninthenorthandcentralcoastandtablelandregions.ThediseaseisnoteasilydistinguishedfromFusariumstalkrot.

Zearalenone ProducedbyF. graminearum,thismycotoxinisimplicatedinsomeformsofinfertilityinpigs,cattleandsheep.Ithasnotbeenproventoaffecthumanhealth.

Trichothecenes PrimarilyproducedbyF. graminearum,butotherFusariumspp.maybeinvolved.Ofthe150relatedtoxins,DON(deoxynivalenol)isthemostimportanttoNSWmaizeproduction.Itisknowntosurviveprocessingandbepresentinhumanfoodproducts.Acuteexposurecansuppressappetite,inducevomitingandaffecttheimunesystem.

Incidenceofzearalenoneisinfledbyrainfallatsilkingandtherelativecobrotresistanceandhuskcoveringofthemaizehybrid.

InNSW,theoccurenceofDONhastodatebeenlimitedtotheLiverpoolPlainsregionwhenabnormallycoolandpersistentlymoistconditionsoccurredthroughgrain maturation.


Section 10 MAIZE - Plant growth regulators and canopy management


December 2014



SECTION10

Plant growth regulators and canopy management

Notapplicableforthiscrop.


Section 11 MAIZE - Crop desiccation/spray out


December 2014



SECTION11

Crop desiccation/spray out

Notapplicableforthiscrop.


Section 12 MAIZE - Harvest


December 2014



SECTION12

Harvest

12.1 Timing

Cropmaturityfromplantingtograinharveststagetakes4.5–6months,dependingon

variety,seasonalconditionsandtimeofplanting.Slowervarietiestendtoyieldmorethan

quickvarieties. 1

Mostendusersrequiregrainmoisturecontentat12–14%,with12%beingoptimalfor

storageon-farm.Asgrainreachesphysiologicalmaturity,moisturecontentisusually

28–34%,whichrequiressignificantdryingdown.Naturaldrydownispossibleuntilearly

May,dependingonlocation.

Maizecandryatarateof0.5–1.0%eachdayinsuitableweatherconditions.Once

conditionsbecomecoolandthelikelihoodofrainincreases,cropscanbeharvestedat

16–18%moisturecontentandartificiallydriedto<14%,ifreturnsforgrainsupportthisor

ifpoorweatherconditionsareimminent.Cropscanbelefttostandoverwinterfornatural

dryingtoresumeinthespring,butthisincreasestheriskofmycotoxincontamination.

Withaccesstodryingfacilities,harvestusuallycommencesat18%grainmoisturecontent

(Figure1).Mostharvestersperformbest,losinganddamaginglessgrain,whenmoisture

contentis18–24%.Aerationequipmentisnotsufficienttodrymaizegraindownto14%

moisture.2

Hybridswithloosehuskcoverdrydownfasterthanthosewithtightcovers.

Althoughgraincanphysicallybeharvestedatupto25%moisture,thisisnotrecommended

becausedryingcostswillbehigh.Wherepossible,growersshouldaimtoharvestasclose

aspossibletotherequireddeliverymoisturepercentage.3

1 DAFF(2012)Harvestingandmarketingformaize.Maizeproduction.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/harvesting-marketing




http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/harvesting-marketing








December 2014



Figure 1: Most harvesters perform best, losing and damaging less grain, when moisture content is >18%.

12.2 Grain for milling markets

Graindestinedformillingmarketsrequiresspecialcareduringharvestandpreparation

forstorage.Grainwithahighproportionofhardendosperm,asrequiredfordrymilling,

ishighlysusceptibletohairlinefracturesknownas‘stresscracks’,inwhichmoisture

evaporatesfromtheendosperm,shrinkingit.Whendryingoccurstooquickly,shrinkageis

uneven,leadingtotheformationofcracks.Duringmilling,gritsbreakupalongthecracks,

makingthemunsuitableforproductssuchascornflakes.

Toreducetheoccurrenceofstresscracks:

• Uselowerdrumspeedsduringharvest.

• Uselarge-diameteraugers(>200mm)operatingatlowspeedsandmaximumholding

capacity.

• Useconveyorbeltsinpreferencetoaugers.

• Reducemoisturecontentofgrainharvested>14%byusingslow,steadydryingrates

withheatedairtemperaturesnotexceeding49°Candgraintemperaturenotexceeding

38°C.

• Slowlycoolgrainthathasbeendried;ideally,drygrainearlyinthedaytoenableslow

coolingasthetemperaturedecreasesintotheevening.

• Preventre-wettingofgrainfromdew,condensationorrain.

• Minimisethenumberoftimesthegrainishandled.4 5



i More information

DWRobinson,CAKirby

(2002)Maizestubble

managementsurvey.

CSIROTechnicalReport

13/02.






http://www.clw.csiro.au/publications/technical2002/tr13-02.pdf







December 2014



12.3 Black layer or physiological maturity

Whenthecropreachesphysiologicalmaturity,or‘blacklayer’,thegrainmoistureis

~28–34%.Thisoccurs~60–66daysaftersilking.Drydownafterreachingblacklayercan

varyfrom0.5%to2%moistureperdayforearly-plantedcropsmaturingduringJanuary–

Februaryinheatwaveconditions.However,duringthecoolerandoftenwetterwinter

months,maizedoesnotcomedowninmoisturemuchbelow16%,untiltheweatherstarts

towarmagain(thismoreofanissuewithlaterplants).

Thesofterendospermtypesandparticularlytheloose-husk-coveredhybridsdrydown

quickerthanthetighterhusk-covered,harderendospermtypes.

Sometimesadecisionhastobemade,ifstalkrotiscausingsomelodging,aboutwhether

toharvestearlyanddrythegrain(eventhoughatanadditionalexpense)ortoleaveittothe

optimummoisturebutriskmuchhigherfieldlosses.

Grainharvestingisnormallydonewithacornfrontwitheitherasnapperfront,whichonly

removestheearandtakesverylittleplantmaterialthroughtheheader,oracutterbar,

wherechainsfeedthecropontothecutterbar(Figure2).Drylandgrowerswithlower

yieldingcropswillalsousesunflowertrays,whichdivideandguidethecropontothecutter

bar,buttheyarenotasefficientinhigh-yieldingcrops.Localexperiencesuggeststhat

drylandcropsof<6t/hacanbeharvestedusingconventionalfrontswithsunflowertrays.

Aswithplantingthecrop,groundspeedisimportantbecauseitaffectstheintakegrain

quantity—toomuchmeansgrainlossesoverthetopsieve.Headermanualsshouldbe

followedforsettinguptheheaderwithregardtodrums,rotorsandcylinders.Theoptimum

cylinderspeedformaizeisusually~350–450rpm.

Figure 2: Grain harvesting is normally done with a corn front with either a snapper front or cutter bar (pictured). (Photo: Pacific Seeds)

Rotorspeedsshouldbeasfastaspracticalwithoutcrackingthegrain.Concavesettings

arealsoimportant;asaguide,theclearanceatthebackoftheconcaveequalsthe

diameterofthecobs.

Notonlywillapoorlysetupheadercrackgrainbutwithsomeofthespecialtymaizessuch

asgrittingmaizeforgritmanufactureandpopcorn,itcancausehairlinestressfractures.

Mostcontractsacceptonlyminimumdamage.Withthenewopportunitiesinexport

markets,crackingofthegraincanalsobeanissuewithtightspecificationstobemet.




December 2014



Post-harvesthandlingofthistypeofmaterialisalsocrucialbecauseaugerscanbevery

abrasiveandwillhavethesameeffectasgrainfallingfromagreatheightintosilos.

Stressfracturingcanalsohappenwithstandingcropsinthepaddock,particularlythe

harderendospermtypeswithlittletipcoverage,looserhuskcoverandquickerdrydown,

andinautumnifthedifferencebetweennightanddaytimeairtemperatureis>30°C.

Incorrectartificialdryingcanalsocausestressfractures,eitherfromexcessiveheat(>50°C)

whentryingtodrytooquickly,orifthegrainisallowedtocooldowntooquicklywithvery

coldoutsideair.

Maizeat15–16%moisturecanbestoredoverthecoolermonthsusingaerators,butonce

theweatherstartstowarmupmoisturewillneedtocomedownto14%.

Aswithallstoredgrain(orevenstandingcrops,particularlylateones),insectswillattack,

particularlyinhumidconditions;therefore,attentionneedstobegiventoapplying

insecticidesorInsectigas®ifstoringforaperiod. 6


i More information

MaizeTradingStandards,

2014/15. Grain Trade

Australia.



Authority.

MaizeAssociationof

Australia.




http://www.graintrade.org.au/sites/default/files/file/Commodity Standards/Section_02_-_Maize_Trading_Standards_201415_Final.pdf








Section 13 MAIZE - Storage


December 2014



SECTION13

Storage

Keypointsforstoringmaize:

• Aerationisanimportantfeatureofmaizestorageinthenorthernregion.Ithasseveral

rolesincludingcoolingmaizepost-harvest,short-termstorageofmaizewithhigher

grainmoisturecontents,aerationdryingandaerationcoolingfollowinghotairdrying.

• Goodstorageandequipmenthygieneshouldbepracticedwithmaizetoavoid

contaminationofotherstoredcropssuchaswheat,whichcanbedowngradedby

evensmallamountsofresidualmaizeseed.

• Maizegrittingandfeedvarietiesmustbecarefullysegregatedinstoragesandaccurate

recordsmaintainedtoensuremarketspecificationsforvariousendusescanbemet.

• Maizeisoneofthefewgraincropsthatcanharbourafieldinfestationofweevils

(Sitophilus zeamais)atharvesttime.Sievegrainsamplesfromtrucksduringharvest

timetoassesswhetherthereisafieldinfestation.

Anon-farmstoragesystemthathasaerationcapabilitiesandisfullysealableisessential

forgrowerswhowishtomaximisetheirreturnsfrommaize.Withoutpressure-tested,

sealablesilos,growerscouldbecontributingtoAustralia’sproblemofinsectresistance

tophosphine,themostcommonfumigantusedintheAustraliangrainindustry.Without

aerationcooling,growersareincreasingthelikelihoodofregularpestinfestationand

problemswithmouldygrain.

Inconjunctionwithsoundmanagementpractices,whichincluderegularmonthlymonitoring

andrecordingforstoragepestsandgrainquality,ensuringaerationsystemsareoperating

efficiently,andgoodhygienelevels,anon-farmstoragesystemthatiswelldesignedand

maintainedprovidesthebestinsuranceforthegroweronthequalityofgraintobeout-

turned.

GrainTradeAustraliastipulatesstandardsforheat-damaged,bin-burnt,storage-mould-

affectedorrottenwheat,allofwhichcanresultinthediscountingorrejectionofgrain.1

Effectivemanagementofstoredgraincaneliminatealloftheseriskstoquality.

ForDarlingDownsproducers,targettemperaturesofstoredwheatshouldbe20–23°C

duringsummerand<15°Cinwinter.2

1 GTA(2013)WheatStandards,2013/2014season.GrainTradeAustralia,August2013,http://www.graintrade.org.au/sites/default/files/file/Commodity%20Standards/Section%2002%20-%20Wheat%20Standards%20201314.pdf

2 PBurrill(2013)GrainStorageFuture:pestcontroloptionsandstoragesystems2013–2014.GRDCUpdate,July2013, http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/07/Grain-Storage-Future-pest-control-options-and-storage-systems-2013-2014

i More information

Northernsouthern

regionsstoredgrain

pests—identification.

GRDC Stored Grain

Information Hub.

Storedgrainpests

identification—theback

pocketguide2011.

GRDC Stored Grain

Information Hub.

SC Kimenju, H De Groot

(2010)Economicanalysis

of alternative maize

storagetechnologiesin

Kenya.AAAE/AEASA

Conference.

EYHosang(2012)An

alternativestorage

techniqueformaintaining

maizeseedqualityin

WestTimor.Australian

AgronomyConference.


http://www.graintrade.org.au/sites/default/files/file/Commodity Standards/Section 02 - Wheat Standards 201314.pdf



http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/07/Grain-Storage-Future-pest-control-options-and-storage-systems-2013-2014


http://storedgrain.com.au/northern-southern-regions-stored-grain-pests-identification/





http://storedgrain.com.au/stored-grain-pests-identification-the-back-pocket-guide-2011/





http://ageconsearch.umn.edu/bitstream/96419/2/169. Economic Analysis of Alternative Maize Storage Technologies in Kenya.pdf














December 2014



13.1 Grain insecticides

Useinsecticidesonlyinaccordancewiththelabelandifapprovedbypotentialbuyers.3

Commerciallyavailableproductswillusuallyincludeamixtureofinsecticides(Table1).Seek

advicebeforeusetoensureoptimumpestcontrolandappropriatelabelcompliance

Table 1: Insecticides for used with stored cereal grains including barley, maize, millets, oats, rice, sorghum, triticale, wheat

Insecticide

Storage period

Withholding period and restrictions on use

6 weeks–3 months 3 months–9 months

Rate per t Cost per t Rate t Cost per t

Pirimiphos-methyl(900g/Lproduct)

4.5 mL 30–35cents

4.5 mL 30–35cents

Nowithholdingperiod

Chlorpyrifos-methyl(500g/Lproduct)

10 mL 75–80cents

20 mL 150–160cents

Nowithholdingperiod,donotapplytoriceormaltingbarley

Fenitrothion(1000g/Lproduct)

6 mL 18–20cents

12 mL 35–40cents

Withholdingperiod90daysforthehighrate

Deltamethrin(e.g.250g/Lproduct)+piperonylbutoxide

4 mL 15–20cents

4 mL 15–20cents

Nowithholdingperiod(okayformaltbarley&sorghum).Maynotbegenerallyavailable

Methoprene S-methoprene Spinosad

5 mL

20 mL

2 mL

150–160cents

5 mL

20 mL

2 mL

150–160cents

Nowithholdingperiod

Nowithholdingperiod

Nowithholdingperiod;commercialproductmixwithspinosadnottobeusedonmaize,riceormaltbarley

PointstonotesinrelationtoTable1:

• Alwayscheckdoseratesandallotherdetailsontheproductlabelandmanufacturer’s

instructions.Table1isaguideonly.Someproductsaretwo-tinmixtures,e.g.Conserve

On-Farm®containschlorpyrifos-methyl,s-methopreneandspinosad.

• Diluteliquidconcentratesinwateratthespecifiedrateperlitre,thenspray1Lmixture/t

grainwhileauguringthegrain.

• Insecticideresiduesmustnotexceedmaximumresiduelimits(MRL).Whereapplication

ratesexceedMRL,growersmustwaitthewithholdingperiodtoallowresiduesinthe

graintodecaytolessthantheMRLbeforesellingthegrain.

• Seedlingsofsomesorghumvarietiesaresusceptibletotoxicityfrom

organophosphorusinsecticidessuchaspirimiphos-methyl,fenitrothionand

chlorpyrifos-methyl.4

3 DAFF(2010)Chemicalstotreatinsectsinstoredgrain.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/grain-storage/chemicals

4 DAFF(2010)Chemicalstotreatinsectsinstoredgrain.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/grain-storage/chemicals

i More information



Authority.


http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/grain-storage/chemicals









December 2014



13.2 How to store maize on-farm

AccordingtotheKondininGroupNationalAgriculturalSurvey2011,silosaccountfor79%

ofAustralia’son-farmgrainstorage,comparedwith12%forbunkersandpitsand9%for

grainbags.

Aerated,sealablesilosarewidelyacknowledgedasthemosteffectivewaystostoregrain

on-farm(Table2).Thereisnocompulsorymanufacturingstandardforsealedsilosin

Australia;however,avoluntaryindustrystandardwasadoptedin2010.WatchthisGRDC

GroundCoverTVcliptofindoutmore:http://www.youtube.com/watch?v=iS3tUbJZl6U

Table 1: Advantages and disadvantages of grain storage options

Storage type Advantages DisadvantagesGas-tightsealablesilo • Gas-tightsealablestatusallowsphosphine

andcontrolledatmosphereoptionstocontrolinsects

• Easilyaeratedwithfans• Fabricatedon-siteoroff-siteandtransported• Capacityfrom15tonnesupto3000tonnes• Upto25yearplusservicelife• Simple in-loading and out-loading• Easilyadministeredhygiene(conebase

particularly)• Canbeusedmultipletimesin-season

• Requiresfoundationtobeconstructed• Relativelyhighinitialinvestmentrequired• Sealsmustberegularlymaintained• Accessrequiressafetyequipmentand

infrastructure• Requiresanannualtesttocheckgas-tightsealing

Non-sealedsilo • Easilyaeratedwithfans• 7–10%cheaperthansealedsilos• Capacityfrom15tonnesupto3000tonnes• Upto25yearplusservicelife• Canbeusedmultipletimesin-season

• Requiresfoundationtobeconstructed• Silocannotbeusedforfumigation—see

phosphinelabel• Insectcontroloptionslimitedtoprotectantsin

easternstatesanddryacideinWA.• Accessrequiressafetyequipmentand

infrastructure

Grainstoragebags • Lowinitialcost• Canbelaidonapreparedpadinthepaddock• Provideharvestlogisticssupport• Canprovidesegregationoptions• Are all ground operated• Canaccommodatehigh-yieldingseasons

• Requirespurchaseorleaseofloaderandunloader• Increasedriskofdamagebeyondshort-term

storage(typicallythreemonths)• Limitedinsectcontroloptions,fumigationonly

possibleunderspecificprotocols• Requiresregularinspectionandmaintenance

whichneedstobebudgetedfor• Aerationofgraininbagscurrentlylimitedto

researchtrialsonly• Mustbefencedoff• Pronetoattackbymice,birds,foxesetc.• Limitedwetweatheraccessifstoredinpaddock• Needtodisposeofbagafteruse• Single-useonly

Grainstoragesheds • Canbeusedfordualpurposes• 30yearplusservicelife• Lowcostperstoredtonne

• Aerationsystemsrequirespecificdesign• Riskofcontaminationfromdualpurposeuse• Difficulttosealforfumigation• Vermincontrolisdifficult• Limitedinsectcontroloptionswithoutsealing• Difficulttounload


http://www.youtube.com/watch?v=iS3tUbJZl6U



December 2014



Growersshouldpressure-testsealablesilosonceperyeartocheckfordamagedsealson

openings.Storagesmustbeabletobesealedproperlytoensureeffectivefumigation.

Atanindustrylevel,itisingrowers’bestintereststofumigategraininsealablestorages

tohelpstemtheriseofinsectresistancetophosphine.Thisresistancehascomeabout

becauseoftheprevalenceofsilosthatarepoorlysealedorunsealedduringfumigation.5

TheKondininGroupNationalAgriculturalSurvey2009revealedthat85%ofrespondents

hadusedphosphineatleastonceduringtheprevious5years,andofthoseusers,37%

usedphosphineeveryyearforthepast5years.AGRDCsurveyduring2010revealedthat

only36%ofgrowersusingphosphineapplieditcorrectly—inagas-tight,sealedsilo.

Researchshowsthatfumigatinginastoragethatisnotpressure-sealeddoesnotachievea

sufficientconcentrationoffumigantforlongenoughtokillpestsatalllife-cyclestages.For

effectivephosphinefumigation,aminimumgasconcentrationof300partspermillion(ppm)

for7daysor200ppmfor10daysisrequired(Figure1).Fumigationtrialsinsiloswithsmall

leaksdemonstratedthatphosphinelevelsareaslowas3ppmclosetotheleaks(Figure2).

Therestofthesiloalsosuffersfromreducedgaslevels.6

Figure 1:

0

200

400

600

800

1000

1200

1400

1600

1800

0 1 2 3 4 5 6 7 8 9 10

Gas

co

ncen

trat

ion

(pp

m)

Days under fumigation

TopMiddle Bottom

(3.5 minute half-life pressure test)

Gas concentration in gas-tight silo.

5 CWarrick(2011)Fumigatingwithphosphine,otherfumigantsandcontrolledatmospheres:Doitright—doitonce:AGrainsIndustryGuide.GRDCStoredGrainProject,January2011(reprintedJune2013),http://www.grdc.com.au/~/media/FC440FBD7AE14140A08DAA3F2962E501.pdf

6 PBotta,PBurrill,CNewman(2010)Pressuretestingsealablesilos.GRDCGrainStorageFactSheet,September 2010, http://www.grdc.com.au/~/media/0218DA4A22264A31B6202718043758DE.pdf


http://www.grdc.com.au/~/media/FC440FBD7AE14140A08DAA3F2962E501.pdf


http://www.grdc.com.au/~/media/0218DA4A22264A31B6202718043758DE.pdf



December 2014



Figure 2:

0

200

400

600

800

1000

1200

1400

1600

1800

0 1 2 3 4 5 6 7 8 9 10

Gas

co

ncen

trat

ion

(pp

m)

Days under fumigation

TopMiddle Bottom

(8 second half-life pressure test)

Gas concentration in a non-gas-tight silo.

Tofindoutmoreabouthowtopressure-testsilos,visittheGRDCGrainsIndustryGuide:

Fumigatingwithphosphine,otherfumigantsandcontrolledatmospheres.Doitright—doit

once.

Aerationofstoredwheatisakeynon-chemicaltoolusedtominimisetheriskofinsect

infestationsandspoilingthroughheatand/ormoisturedamage.

Aerationcontrollersreducetheamountoftimeneededtophysicallyturnfansonandoff

andtheyincreasethereliabilityofgraincooling,butunitsandstoragefacilitiesmuststillbe

checkedregularly.Mostaerationcontrollershavehourmetersfitted,sorun-timescanbe

checkedtoensurethattheyarewithinrangeoftheexpectedapproximateaverageof100

h/month.

Seriousgraindamagehasoccurredwhenfanperformancehasnotmettherequiredairflow

rateasmeasuredinlitrespersecondpertonne(L/s.t).Whengrainwithelevatedmoisture

levelsiscooledordried,aninadequateairflowrateand/orapoorsystemdesigncancause

sectionsofthestoragetodevelopveryhighgraintemperatures.Whenaerationdrying,

moisturedryingfrontscanbemovingtooslowlytopreventgrainspoilage.Grain-quality

lossesfrommouldsandinsectdamagecanoccurrapidly.Thistypeofdamageoftenmakes

thegraindifficulttosellandmaycausephysicaldamagetothesiloitself.7

ResearchersinAustraliahavedevelopedadevicethatmeasuresworkingairflowrates

offansfittedtograinstorage.Calledthe‘A-Flow’,ithasbeenvalidatedundercontrolled

conditions,usinganAustralianStandardfan-performancetestrig,tobewithin2.6%ofthe

truefanoutput.Thedevicewasusedonatypicalgrainstoragethatwasintheprocess

ofaeratingrecentlyharvestedgrain.Afanadvertisedtoprovide1000L/s(equivalentto

6.7L/s.tonafull150-tsilo)wasdemonstratedtobeproducingonly1.8L/s.t.Becauseof

thistest,thefarmerrecognisedaneedtomakechangestohisaerationsystemdesign.

Severalchangesmayberequiredifairflowratesarenotsuitableforefficientaeration

coolingordrying.Anewfanthatisbettersuitedtothetaskcouldbeinstalled,asecondfan

added,ortheamountofgraininthesiloreducedtoincreaseflowratepertonneofgrain.

7 PBurrill,ARidley(2012)Performancetestingaerationsystems.GRDCResearchUpdateNorthernRegion,Spring2012,Issue66,http://www.grdc.com.au/~/media/DAF5F438D9644D90B9A4FA9716B2014E.pdf




http://www.grdc.com.au/~/media/DAF5F438D9644D90B9A4FA9716B2014E.pdf



December 2014



AGRDCGrainStorageFactSheetexplaininghowtobuildanduseanA-Flowisavailable:

Performancetestingaerationsystems.

Detailedinformationaboutselecting,sitingandfitting-outsilos,grainstoragebags,sheds

andbunkersiscontainedintheGRDCGrainsIndustryGuide:Grainstoragefacilities.

Planning forefficiencyandquality.

13.3 Hygiene

Effectivegrainhygieneandaerationcoolingcanovercome70%ofpestproblemsinstored

grain.Allgrainresiduesshouldbecleanedoutwhensilosandgrain-handlingequipment

arenotinusetohelpminimisetheestablishmentandbuild-upofpestpopulations.Inone

year,abagofinfestedgraincanproduce>1millioninsects,whichcanwalkandflytoother

grainstorageswheretheywillstartnewinfestations.Meticulousgrainhygieneinvolves

removinganygrainthatcanharbourpestsandallowthemtobreed.Grainpestslivein

dark,shelteredareasandbreedbestinwarmconditions.

AtrialinQueenslandrevealed>1000lessergrainborers(Rhyzopertha dominica)inthe

first40Lofgrainthroughaharvesteratthestartofharvest;thisharvesterwasconsidered

reasonablycleanattheendofthepreviousseason.8FurtherstudiesinQueensland

revealedthatinsectsareleastmobileduringthecoldermonthsoftheyear.Cleaningaround

silosinmidwinter(June,July)canreduceinsectnumbersbeforetheybecomemobile.

Successfulgrainhygieneinvolvescleaningallareaswheregrainbecomestrappedin

storagesandequipment.Grainpestscansurviveinatinyamountofgrain,whichcangoon

toinfestanyparceloffreshgrainthroughthemachineorstorage.Harvestersandgrain-

handlingequipmentshouldbecleanedoutthoroughlywithcompressedairafteruse.

Aftergrainstoragesandhandlingequipmentarecleaned,theyshouldbetreatedwitha

structuraltreatment.Diatomaceousearth(DE)isanamorphoussilicaknowncommercially

asDryacide®andiswidelyusedforthispurpose.Itactsbyabsorbingtheinsect’scuticle

orprotectiveexterior,causingdeathbydesiccation.Ifappliedcorrectlywithcomplete

coverageinadryenvironment,DEcanprovideupto12months’protectionbykillingmost

speciesofgraininsectsandwithnoriskofresistancedeveloping.Itcanbeappliedasa

dustorslurry.

Althoughsomegrainbuyersacceptsmallamountsofresidueoncerealgrainsfrom

chemicalstructuraltreatments,growersshouldavoidusingthem,orshouldwashthe

storageoutbeforestoringoilseedsandpulses.Growersareadvisedtocheckthegrain

buyer’sdeliverystandardsforMRLallowancesbeforeusinggrainprotectantsorstructural

treatments.

Tofindoutmoreaboutwhattouseandwhenandhowtocleanequipmentandstoragesto

minimisethechanceofinsectinfestation,downloadtheGRDCGrainStorageFactSheets

Hygieneandstructuraltreatmentforgrainstorages(June2013)andManaging maximum

residueLimitsinexportgrains(July2014).

8 PBurrill,PBotta,CNewman,BWhite,CWarrick(2013)Northernandsouthernregions—Grainstoragepestcontrolguide.GRDCGrainStorageFactSheet,June2013,http://www.grdc.com.au/GRDC-FS-GrainStoragePestControl

i More information

Grainstoragefacilities:

Planningforefficiency

andquality.


http://www.grdc.com.au/Resources/Factsheets/2012/08/Grain-Storage-Performance-testing-aeration-systems

http://storedgrain.com.au/wp-content/uploads/2013/07/GRDC-GS-FACILITIES-Booklet-2013_Final.pdf


http://www.grdc.com.au/GRDC-FS-HygieneStructuralTreatments

http://www.grdc.com.au/GRDC-FS-ManagingMRLs

http://www.grdc.com.au/GRDC-FS-ManagingMRLs

http://www.grdc.com.au/GRDC-FS-GrainStoragePestControl







December 2014



13.4 Grain protectants and fumigants

AccordingtoGrainTradeAustralia,somechemicalsusedtotreatstoredgrainwerenot

approvedforgrain,andiftheyaredetected,anentireloadcanberejected.Somemarkets

callforPRF(‘pesticideresiduefree’),whichdoesnotruleouttheuseofsomefumigants,

includingphosphine.However,PRFgrainshouldnothaveanydetectablechemicalresidues

fromtreatmentsthatareapplieddirectlytothegrainasgrainprotectantsforstorage

purposes.Beforeusinganewgrainprotectantorfumigant,growersareadvisedtocheck

withprospectivebuyers,astheuseofsomechemicalmayexcludegrainfromcertain

markets.

Althoughphosphinehasresistanceissues,itiswidelyacceptedashavingnoresidue

issues.Thegrainindustryhasadoptedavoluntarystrategytomanagethebuild-up

ofphosphineresistanceinpests.Itscorerecommendationsaretolimitthenumberof

conventionalphosphinefumigationsonundisturbedgraintothreeperyear,andtoemploy

abreakstrategy.Thebreakisprovidedbymovingthegraintoeliminatepocketswhere

thefumigantmayfailtopenetrate,andbyretreatingitwithanalternativedisinfectantor

protectant. 9

Recentresearchhasidentifiedthegenesresponsibleforinsectresistancetophosphine.

Ageneticanalysisofinsectsamplescollectedfromsouth-easternQueenslandbetween

2008and2012hasallowedresearcherstoconfirmtheincreasingincidenceofphosphine

resistanceintheregion.Whereasfewresistancemarkerswerefoundininsectscollected

5yearsago,anaverageof5%ofinsectscollectedin2011carriedtheresistancegene.

FurthertestingwithDNAmarkersthatcandetectphosphineresistanceisexpectedto

identifyprobleminsectsbeforeresistancebecomesentrenched,andtherebyhelpto

prolongphosphine’seffectivelife.10

9 PCollins(2009)StrategytomanageresistancetophosphineintheAustraliangrainindustry.CooperativeResearchCentreforNationalPlantBiosecurityTechnicalReport,http://www.graintrade.org.au/sites/default/files/file/Phosphine_Strategy.pdf

10 CNorwood(2013)Geneticcluetothwartphosphineresistance.GRDCGroundCover,Issue102,Jan.–Feb.2013, http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-102/Genetic-clue-to-thwart-phosphine-resistance


http://www.graintrade.org.au/sites/default/files/file/Phosphine_Strategy.pdf


http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-102/Genetic-clue-to-thwart-phosphine-resistance




December 2014



Table 2: Resistance and efficacy guide for stored grain insects (cereal grains only)

Note:Beforeapplying,checkwithyourgrainbuyerorbulkhandlersandreadlabelscarefully

Treatments WHP (days)

Lesser grain borer(Rhyzopertha

dominica)

Rust-red flour beetle

(Tribolium castaneum)

Rice weevil(Sitophilus

oryzae)

Saw-toothed

grain beetle (Oryzaephilus surinamensis)

Flat grain beetle

(Cryptolestes ferrugineus)

Psocids (booklice)

(Order Psocoptera)

Structural treatments

Graindisinfectants-usedoninfestedgraintocontrolfulllifecycle(adults,eggs,larvae,pupae).

Phosphine(egFumitoxin®)1,3whenusedingas-tight,sealablestores

2

Sulfurylfluoride(egProFume®)10 1

Dichlorvos(egDichlorvos1140®)11 7-28 9

Grainprotectants–appliedpostharvest.Pooradultcontrolifappliedtoinfestedgrain.

Pirimiphos-methyl(egActellic 900®)

nil2

Fenitrothion(egFenitrothion1000®)4

1-90

Chlorpyrifos-methyl(egreldanGrainProtector®)5

nil2

Methoprene(GrainStar 50®) nil6 7 7

‘Combinedproducts’(egReldanPlusIGRGrainProtector)

nil2

Deltamethrin(egK-Obiol®)10 nil2

Diatomaceousearth,amorphoussilica–effectiveinternalstructuraltreatmentforstoragesandequipment.Specificusegraintreatments.

Diatomaceousearth,amorphoussilica(egDryacide®)8

nil2

WHPWithholdingPeriod

Notregisteredforthispest High-levelresistanceinflatgrainbeetlehasbeenidentified,sendinsectsfortestingiffumigationfailuresoccur Resistantspecieslikelytosurvivethisstructuraltreatmentforstorageandequipment Resistancewidespread(unlikelytobeeffective) Effectivecontrol

1unlikelytobeeffectiveinunsealedsites,causingresistance,seelabelfordefinitions 2Whenusedasdirectedonlabel 3Totalof(exposure+ventilation+withholding)=10to27days 4Nufarmlabelonly 5Storedgrainsexceptmaltingbarleyandrice/storedlupinsregistrationforVictoriaonly/notonstoredmaizedestinedforexport 6Whenappliedasdirected,donotmovetreatedgrainfor24hours 7Periodsof6–9monthsstorageincludingmixtureinadulticide,egFenitrothionatlabelrate 8Donotuseonstoredmaizedestinedforexport,orongraindeliveredtobulk-handlingauthorities 9Dichlorvos500g/Lregistrationonly 10Restrictedtolicensedfumigatorsorapprovedusers 11Restricedtouseunderpermit14075only.Unlikelytobepracticalforuseonfarm

Source:RegistrationinformationcourtesyofPestgenie,APVMAandInfoPest(DEEDI)websites

AccordingtoresearchresultsfromscientistsatQueensland’sDepartmentofAgriculture,

FisheriesandForestry(DAFF),sulfurylfluoride(SF)hasexcellentpotentialasanalternative

fumiganttocontrolphosphine-resistantgrainstoragepests(Table2).Itiscurrently




December 2014



registeredinAustraliaasagraindisinfectant.SuppliedunderthetradenameProFume,SF

canbeusedonlybyalicensedfumigator.

FieldtrialshaveshownthatSFcancontrolstronglyphosphine-resistantpopulationsofrusty

grainbeetle(Cryptolestes ferrugineus),alsoknownasoneoftheflatgrainbeetles.Monthly

samplingoffumigatedgrainhasrevealednoliveinsectsfor3consecutivemonthsinlarge-

scalebunker(pad)storagesafterthefumigation.

Annualresistance-monitoringdatawereanalysedtoassesstheimpactofusingSFas

analternativefumiganttophosphine.ThisrevealedthataftertheintroductionofSFin

centralstoragesacrossthenorthernandsoutherngrainregionsin2010,therewasa50%

reductionintheincidenceofstronglyphosphine-resistantpopulationsofflatgrainbeetleat

theendofthefirstyear,andthedownwardtrendiscontinuing.Complimentarylaboratory

experimentshaveshownthatphosphineresistancedoesnotshowcross-resistancetoSF,

whichisanadditionaladvantageofusingSF.11

Effectivephosphinefumigationcanbeachievedbyplacingthetablets,attheratedirected

onthelabel,ontotraysandhangingtheminthetopofapressure-tested,sealablesilo,or

placingtabletsintoaground-levelapplicationsystemifthesiloisfittedwithrecirculation.

Afterfumigation,grainshouldbeventilatedforaminimumof1daywithaerationfans

running,or5daysifnofansarefitted.Aminimumwithholdingperiodof2daysisrequired

afterventilationbeforegraincanbeusedforhumanconsumptionorstock-feed.Thetotal

timeneededforfumigatingis10–17days.

Tofindoutmore,visittheGRDCGrainIndustryGuide:Fumigating withphosphine,other

fumigantsandcontrolledatmospheres.Doitright—do it once.

Severalnewprotectantsarenowavailable.Theseinclude:

• K-Obiol®(activeingredients(a.i.s)deltamethrin50g/L,piperonylbutoxide400g/L):

featuresacceptableefficacyagainstthecommonstoragepestlessergrainborer,

whichhasdevelopedwidespreadresistancetocurrentinsecticides.Insectresistance

surveyshaveconsistentlydetectedlowlevelsofdeltamethrin-resistantinsectstrains

intheindustry.Thisisawarningthatresistantpopulationscanincreasequicklywith

widespread,excessiveuseofasingleproduct.A‘productstewardship’programhas

beendevelopedtoensurecorrectuseoftheproduct.12

• ConserveOn-Farm®(a.i.schlorpyrifos-methyl550g/L,s-methoprene30g/L,spinosad

120g/L):controlsmostmajorinsectpestsofstoredgrain,includingtheresistantlesser

grainborer.TheMRLshavebeenestablishedwithkeytradingpartnersandthereare

noissueswithmeatresiduebioaccumulation.

• VAPORMATE®(a.i.ethylformate166.7g/kg):approvedforuseinstoredcereals.Itis

registeredonlytocontroltheadultlife-stageofinsects,andisregisteredonlyforcontrol

ofriceweevil,lessergrainborer,rust-redflourbeetle(Triboliumspp.)andpsocids

(booklice).Itmustonlybeusedbyalicensedfumigator.

11 MNayak(2012)Sulfurylfluoride—Asolutiontophosphineresistance?GRDCResearchUpdateNorthernRegion,Spring2012,Issue66,http://www.icanrural.com.au/newsletters/NL66.pdf





http://www.icanrural.com.au/newsletters/NL66.pdf





December 2014



Non-chemicaltreatmentoptionsinclude:

• Carbondioxide(CO2):involvesdisplacingtheairinsideagas-tightsilowitha

concentration of CO2highenoughtobetoxictograinpests.Toachieveacompletekill

ofallofthemaingrainpestsatalllife-stages,CO2mustbemaintainedataminimum

concentrationof35%for15days.

• Nitrogen(N2):providesinsectcontrolandqualitypreservationwithoutchemicals.Itis

safetouseandenvironmentallyacceptable,andthemaincostisthecapitalcostand

electricityusedbyequipmenttogeneratetheN2.Italsoproducesnoresidues,so

grainscanbetradedatanytime,unlikechemicalfumigants,whichhavewithholding

periods.InsectcontrolwithN2involvesmodifyingtheatmospherewithinthegrain

storagetoremoveallcomponentsexceptN2,therebystarvingthepestsofoxygen.13

Silobagsandsealablesiloscanbefumigated.ResearchconductedbyAndrewRidley

andPhilipBurrillfromDAFFandQueenslandfarmerChrisCookhasfoundthatsufficient

concentrationsofphosphinecanbeobtainedfortherequiredtimetofumigategrain

successfullyinasilobag.Trialsonatypical,75-m-longbagcontainingapproximately230t

ofgrainweresuccessfulincontrollingalllifestagesofthelessergrainborer.

Whenusingphosphineinbags,andbecauseofresidueissues,itisillegaltomixphosphine

tabletswithgrain.Theyshouldbeseparatedbyusingperforatedconduittocontaintablets

andspentdust.The1-mtubescanbespearedhorizontallyintothesilobagandremoved

attheendofthefumigation.Trialresultssuggestthatthespearsshouldbenomorethan

7mapartandfumigationshouldoccurover12–14days(Figure3).Inprevioustrialswhen

spearswerespaced12mapart,thephosphinediffusedthroughthegraintooslowly.14

Figure 3:

Day of fumigation

Pho

sphi

ne c

onc

entr

atio

n (p

pm

)

1

1200

1000

800

600

400

200

02 3 4 5 6 7 8 9 10 11 12 13 14 15

6m4m2mPH3 release point

Spread of phosphine gas in a silo bag from a release point to gas monitoring lines at 2, 4 and 6 m along a silo bag.

13 CWarrick(2011)Fumigatingwithphosphine,otherfumigantsandcontrolledatmospheres.Doitright—doitonce:AGrainsIndustryGuide.GRDCStoredGrainProject,January2011(reprintedJune2013),http://www.grdc.com.au/~/media/FC440FBD7AE14140A08DAA3F2962E501.pdf

14 PBurrill,ARidley(2012)Silobagfumigation.GRDCResearchUpdateNorthernRegion,Spring2012,Issue66,http://www.grdc.com.au/~/media/DAF5F438D9644D90B9A4FA9716B2014E.pdf







December 2014



13.5 Aeration during storage

Aerationisavitalpartofthepest-controlstrategy,andreducingstoredgraintemperatures

byatleast10°Cduringsummersignificantlyreducesthethreatofaseriousinsect

infestation,helpingtomaintaingrainquality.Exceptduringtheshort2-weekfumigation

periods,wheatisbeststoredunderaerationcoolingmanagementatalltimes(Figure4).

ProducersintheDarlingDownsandnorthernNewSouthWalesshouldachievegrain

temperaturesinstorageof20–23°Cduringsummerstorageand<15°Cinwinter.15

Figure 4:

26 N

ov

3 Dec

10 D

ec

17 D

ec

24 D

ec

31 D

ec7 J

an

14 Ja

n

21 Ja

n

28 Ja

n4 F

eb

11 Fe

b

18 Fe

b

25 Fe

b

40

30

20

10

0

Tem

per

atur

e (o

C)

non-aeratedaerated air min

Comparison of wheat grain temperatures in aerated and non-aerated silos in New South Wales. (Source: Barry Wallbank, NSW DPI)

Withoutaeration,grainisaneffectiveinsulatorandwillmaintainitswarmharvest

temperatureforalongtime.Grainattypicalharvesttemperaturesof25–35°Candmoisture

content>14–15%providesidealconditionsformouldandinsectgrowth(Table3).16

Go‘on-farm’withGroundCoverTVtoseeanexplanationofthenationalstandardfor

sealedsilos.


16 :PBurrill,PBotta,CNewman,BWhite,CWarrick(2013)Dealingwithhigh-moisturegrain.GRDCGrainStorageFactSheet,June2013,http://www.grdc.com.au/~/media/36D51B725EF44EC892BCD3C0A9F4602C.pdf


http://youtu.be/iS3tUbJZl6U



http://www.grdc.com.au/~/media/36D51B725EF44EC892BCD3C0A9F4602C.pdf

http://youtu.be/iS3tUbJZl6U



December 2014



Table 3: Effect of grain temperature on insects and mould (source: Kondinin Group)

Grain temperature (oC)

Insect and mould development Grain moisture content (%)

40-55 Seeddamageoccurs,reducingviability

30-40 Mouldandinsectsareprolific >18

25-30 Mouldandinsectsactive 13-18

20-25 Moulddevelopmentislimited 10-13

18-20 Younginsectsstopdeveloping 9

<15 Mostinsectsstopreproducing, mouldstopsdeveloping

<8

Althoughadultinsectscanstillsurviveatlowtemperatures,mostyoungstoragepestsstop

developingattemperatures<18–20°C.Attemperatures<15°C,thecommonriceweevil

stopsdeveloping.Lifecyclesofinsectpests(egg,larva,pupaandadult)arelengthened

fromthetypical4weeksatwarmtemperatures(30–35°C)to7–15weeksatcooler

temperatures(20–23°C).

ResearchbytheNSWDepartmentofPrimaryIndustrieshasshownthatgraintemperature

shouldbekept<15°Ctoprotectseedqualityandstopallmajorinsectinfestations,and

aerationslowstherateofdeteriorationofseedifthemoisturecontentiskeptat12.5–14%.17

ApilottrialbytheQueenslandDepartmentofEmployment,EconomicDevelopment

andInnovationshowedhowrapidlyhigh-moisturegraingeneratesheatwhenputintoa

confinedstorage,suchasasilo.Wheatwith16.5%moisturecontentatatemperatureof

28°Cwasputintoasilowithnoaeration.Withinhours,thegraintemperaturereached39°C

andwithin2daysreached46°C,providingidealconditionsformouldgrowthandgrain

damage(Figure5).18

Figure 5:

10 15 20 25

40

35

30

25

20

15

10

5

0

Tem

per

atur

e °C

Moisture content (%)

Rapid pest reproductionRapid mould growth

Deteriorated grain quality

Mould and pest risk, deteriorated germinationBest

long-term storage

Reduced mould and pest risk,

best short-term storage

Effects of temperature and moisture on stored grain.

(Source:CSIROEcosystemsSciencesaspublishedinhttp://www.grdc.com.au/~/media/36D51B725EF44EC892BCD3C0A9F4602C.pdf)

17 NSWDepartmentofPrimaryIndustriesDistrictAgronomists(2007)Wheatgrowthanddevelopment.PROCROPSeries,NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0006/449367/Procrop-wheat-growth-and-development.pdf

18 PBurrill,PBotta,CNewman,BWhite,CWarrick(2013)Dealingwithhigh-moisturegrain.GRDCGrainStorageFactSheet,June2013,http://www.grdc.com.au/~/media/36D51B725EF44EC892BCD3C0A9F4602C.pdf




http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0006/449367/Procrop-wheat-growth-and-development.pdf





December 2014



Ifuseofagraindryerisnotanoption,grainthatisoverthestandardsafestoragemoisture

contentof12%anduptothemoderatemoisturelevelof15% canbemanagedinstorage

forshortperiodsoftimebycontinuallyrunningaerationcoolingfans.However,grainneeds

tobepromptlybroughtdowntosafestoragemoisturecontentsbyeitherblendingwithlow-

moisturegrain,thenaerating,ordryingusingheatedairdryingequipmentfollowedagainby

aerationcooling(Figure6).

Figure 6:

BlendingLayered blending

with aeration

Air inAir in

Incorrect layering

Correct blending. (Source: Kondinin Group)

Aerationdryingforceslargevolumesofairthroughthegraininstorageandslowlyremoves

moisture.Supplementaryheatingcanbeaddedifhighambienthumidityisaproblem.Itcan

bedoneinapurpose-builtaeration-dryingsilo(e.g.Kotzurdryingsilo)orapartlyfilledsilo

withhigh-capacityaerationfansproducing15–25Lair/s.t.

Dedicateddrierscanbeusedtodrywheatinbatchesorwithcontinuous-flow,beforeit

isputintosilos,butexcessiveheatappliedpost-harvestcanreducethequalityofmilling

wheatorthegerminationofplantingseed.Aerationdryingcanreducetheserisks.

Awetharvestordampconditionscanmakedryingpriortostorageanecessity.Theserules

willhelpyoutodecidewhetheritissafetostoreyourwheatwithoutdrying:

• Wheatthatdoesnotexceedthemaximummoisturelevelof12.5%canbecooled

withoutdryingtoslowinsectdevelopmentandmaintainqualityduringstorage.

• Forgrainofupto15%moisture,ifdryingequipmentisnotavailableimmediately,

moderatelymoistgraincanbecooledforashortperiodtoslowmouldandinsect

development,thendriedwhentherightequipmentisavailable.

• Afterdryingtotherequiredmoisturecontent,grainshouldbecooledtomaintain

quality.

• Grainof>15%moisturerequiresimmediatemoisturereductionbeforecoolingfor

maintenance.Ifoverheatingoccursduringartificialdryingorbecauseofover-moisture

storage,somegrainsarelikelytobedeemed‘heatdamaged’or‘binburnt’.

Tofindoutmore,downloadtheGRDCFactSheetDealingwithhigh-moisturegrain.





December 2014



13.6 Monitoring grain

Growersareadvisedtomonitorallgrainstoragesatleastmonthly.Forgraininhigherrisk

situations,monitorevery2weeksduringwarmerperiodsoftheyear.Insectpestspresentin

on-farmstoragesmustbeidentifiedsothatgrowerscanusethebestofbothchemicaland

non-chemicalcontrolmeasurestocontrolthem.

Thoroughsamplingandsievingforinsectsandqualityinspectionsarerequired.Numberall

silosandstoragesandkeepmonthlyrecordsofinsectpestsfound.Anygraintreatments

appliedshouldalsoberecorded.Ifpossible,themoistureandtemperatureofthegrainat

thebottomandtopofthestackshouldbesafelycheckedregularly.19

Riceweevil(Sitophilus oryzae),lessergrainborer(Rhyzopertha dominica)andrust-red

flourbeetle(Tribolium castaneum)aresomeofthemostcommoninsectpestfoundin

storedcereals.Otherspeciestowatchforincludepsocids(booklice),saw-toothedgrain

beetle(Oryzaephilusspp.),flatgrainbeetle(Cryptolestesspp.),Indianmealmoth(Plodia

interpunctella)andangoumoisgrainmoth(Sitotroga cerealella).Severalotherbeetles,and

mites,aresometimespresentaspestsinstoredcerealgrainandprocessedproducts.

PhotographsanddescriptionsofthesepestscanbefoundintheGRDCGrainStorageFact

SheetNorthern and southern regions stored grain pests—Identification.Downloaditfrom:

http://storedgrain.com.au/northern-southern-regions-grain-storage-pest-control-guide/ or

http://www.grdc.com.au/GRDC-FS-StoredGrainPestID.

ThisFactSheetalsooutlineshowtomonitorstoredgrainforinfestations.Herearesome

basicpointstofollowwhenmonitoringforinsectpestsinyourgrain:

• Samplefromthetopandbottomofgrainstoresforearlypestdetection.Insectprobe

orpitfalltrapsinstalledinthetopofthegrainstorewilloftenshowinsectactivitybefore

theyareseenonthesurfaceofthegrain.

• Sievesamplesontoawhitetraytomakesmallinsectseasiertosee.Sievesshouldbe

of2-mmmeshandneedtoholdatleast1Lofgrain.Holdthetrayinthesunlight.This

warmsinsectsandencouragesmovement,makingpestseasiertosee.

• Tohelpidentifylivegrainpests,placethemintoacleanglasscontainerat>20°Cto

encourageactivitywithoutoverheatingorkillingthem.Weevilsandsaw-toothedgrain

beetlescanwalkupthewallsoftheglasseasily,butflourbeetlesandlessergrainborer

cannot.Lookcloselyattheinsectswalkinguptheglass—weevilshaveacurvedsnout

atthefrontandsaw-toothedgrainbeetlesdonot.20

RecentresearchinsouthernandcentralQueenslandhasshownthatindustrymayneed

toconsideranarea-wideapproachtopestandresistancemanagement.Theresearch

studiedtheflightdispersalbythelessergrainborerandtherust-redflourbeetleand

involvedsettingbeetletrapsalonga30-kmtransectintheEmeralddistrict.Itshowedthat

thelessergrainborerfliesallyearroundinCentralQueensland,whereastheflourbeetle

appearedtobelocatedmainlyaroundstoragesduringthewintermonths,spreadinginto

19 PBurrill,PBotta,CNewman(2010)Aerationcoolingforpestcontrol.GRDCGrainStorageFactSheet,September 2010, http://www.grdc.com.au/~/media/AB8938CFDCCC4811AD218B45C308BEBD.pdf

20 PBurrill,PBotta,CNewman,BWhite,CWarrick(2013)Northernandsouthernregionsstoredgrainpests—Identification.GrainStorageFactSheet,June2013,http://www.grdc.com.au/GRDC-FS-StoredGrainPestID


http://storedgrain.com.au/northern-southern-regions-grain-storage-pest-control-guide/

http://www.grdc.com.au/GRDC-FS-StoredGrainPestID

http://www.grdc.com.au/~/media/AB8938CFDCCC4811AD218B45C308BEBD.pdf




December 2014



thesurroundingdistrictinsummer.Thisstudyhighlightstheimportanceoffindingand

dealingwithinfestationsinstoragesandanydumpsofoldgraintolimitthenumberofpests

thatcaninfestcleangrain.

NOTE:ExoticpestsincludingKhaprabeetle(Trogoderma granarium)andthefungaldisease

Karnalbunt(Tilletia indica)areathreattotheAustraliangrainsindustry—reportsightings

immediately.


Section 14 MAIZE - Environmental issues


December 2014



SECTION14

Environmental issues

Theoptimumtemperatureformaizegrowthanddevelopmentis18°–32°C,with

temperaturesof≥35°Cconsideredinhibitory.Theoptimumsoiltemperaturesfor

germinationandearlyseedlinggrowthare≥12°C,andattasselling21°–30°Cisideal.

Maizeisgrowngloballyfrom50°Nto40°S,andfromsealevelupto4000maltitude.Maizeis

ashort-dayplant,with12.5h/daysuggestedasthecriticalphotoperiod.Photoperiodslonger

thanthismayincreasethetotalnumberofleavesproducedpriortoinitiationoftasselling,and

mayincreasethetimetakenfromemergencetotasselinitiation(Birch1997). 1

14.1 Frost issues

Lowautumntemperaturescankillmaizetissuebeforetheplantreachesmaturity.When

anearlyautumnfrostoccurs,maizegrowersneedtoknowtheimpactofthedamage

onhybridmaturityandyield.ThetechnicalbulletinAutumnfrostedmaizecropsprovides

informationontheeffectoffrostonmaize,outlinesoptionsforhandlingfrostedcropsand

discusseswaystoreducetheriskoffrostdamage.2

14.1.1 Conditions causing frost damageTheseverityoffrostdamagewilldependlargelyonthedurationandextentoffreezing

temperatures.Substantialfrostdamageofleaf,stalkandstemtissuemayoccurif

temperaturesdropbelow0°Cfor4–5horwhentemperaturedropsto–2°Corlessfor

evenafewminutes.Frostdamageduetorapidheatlossfromwithinthecropcanoccur

whentemperaturesareseveraldegreesabovezeroiftheairisclearandstill.Underthese

circumstances,leaftemperaturescandropbelowtheactualairtemperature.

Whenairtemperatureisclosetofreezing,frostingcanoccurinlow-lyingareas,wherethe

coldairtendstoaccumulate.Higherareaswithinthesamepaddockmaynotsustainany

frostdamage.Adensemaizecropcantrapconsiderablewarmthwithinitscanopy.Outer

rowsandareasofpaddocksthathavelowplantpopulationsaremorefrost-prone.

1 SBelfield,CBrown(2008)Fieldcropmanual:maize.AguidetouplandproductioninCambodia.CambodianAgriculturalResearchandDevelopmentInstituteandNSWDepartmentofPrimaryIndustries,http://aciar.gov.au/files/node/8919/maize%20manual%2072dpi.pdf

2 Autumnfrostedmaizecrops.TechnicalInsights.PioneerBrandProducts,http://www.pioneer.co.nz/maize-grain/product-information/grain-technical-insights/autumn-frosted-maize-crops.html

i More information

CJBirchet al.(2003)

Agronomyofmaizein

Australia—inreview

andprospect.In

5thAustralianMaize

Conference.


http://www.pioneer.co.nz/maize-grain/product-information/grain-technical-insights/autumn-frosted-maize-crops.html





http://espace.library.uq.edu.au/eserv.php?pid=UQ:9698&dsID=Agronomy_of_Maiz.pdf








December 2014



Maizeplantpartsvaryinsusceptibilitytofrostdamage.Leavesaremostsusceptible

becausetheirthinnessmakesitdifficultforthemtoholdheat.Thickerplanttissuessuchas

stalks,husksandgrainhavegreaterheat-retentioncapabilities. 3

14.1.2 Assessing frost damageAvisualinspectionoffrost-damagedmaizeshouldbemadethemorningafterthefrost,

afterthesunhasrisenandthecrophasbeguntothaw.Atthistime,damagedtissuewill

begintowitherandcellcontentswillbereleasedasasugarycoatingontheleavesand

stem.

Whenassessingthecrop,takeintoaccountthenumberofleavesthathavebeenfrosted,

coborstalkdamage,andtheproportionofthepaddockthathasbeenaffected.Itis

importanttoassessthestageofmaturityofthecropintermsofhowfarthecropwasfrom

harvestwhenitwasfrosted.Outerrowsandanyhollowsinthecroparelikelytobemore

affectedbyfrostthantherestofthecrop.Alwayswalkwellintoandthroughthecropto

makeanaccurateassessmentofdamage.Generally,warmerairisentrappedinthemain

bodyofthecropandtheinitialfrostdoesnotpenetratethecropcanopyasfar.4

Theeffectofafrostongrainyieldisdeterminedbytheamountofleafthatiskilledandthe

stageofdevelopmentwhenthefrostoccurs.Theclosertheplantistoblacklayer,thelower

theyieldlosscausedbyafrost.Evenifalloftheleavesarekilled,theplantcancontinue

tomatureassugarsaremobilisedfromthestalkstotheear.Graindryweightwillcontinue

toincreaseupuntilblacklayeraslongasthereareleaves(especiallyabovetheear)or

evenifjustthestalkandthehuskcoverarestillgreen.Ifthereareseveraldaysofcool

temperatures(7°–12°C)duringgrainfill,prematureblacklayermayoccurandgrainfillwill

cease.Thiscanhappenevenwithoutafrost.

Thepotentialgrainlossfromanautumnfrostatdifferentstagesofgraindevelopmentis

showninTable1.

Table 1: Potential losses in maize grain yield after frost

AdaptedfromJJAfuakwa,RKCrookston(1984)Usingthekernelmilk-linetovisuallymonitorgrainmaturityinmaize.Crop Science 24, 687-691

Corn development stage

Killing frost (leaves and stalks)

Light frost (leaves only)

Percent yield loss

1/3Milk-line 55 35

_Milk-line 40 25

2/3Milk-line 12 5

Blacklayer 0 0

Graincropsfrostedpriortomilk-linewillhavealowgrainyieldpotentialandthekernelswill

bechaffy.Itisrecommendedthatthesecropsbekeptformaizesilageandlefttomatureto

silageharvestdrymatter(asoutlinedabove).



i More information

Autumnfrostedmaize

crops.TechnicalInsights.

PioneerBrandProducts.

Frost.CornAgronomy.

UniversityofWisconsin.

MDeVries,ASGoggi.

Seedqualitytestsfor

earlydetectionoffallfrost

damage in immature

maizeseed.

Frostriskformaize

silagegrowninSouth

Canterbury.Foundation

forArableResearch.

Increasingmaize

resistancetolodgingand

frost.CropNutrition.Yara

UK.

K Pembleton, RP

Rawnsley(2012)Frost

riskassociatedwith

growing maize for

silageonTasmanian

dairyfarms.Australian

AgronomyConference.

Assessingfrostriskfor

silagemaize.Programs.

TasmanianInstitutefor

Agriculture.









http://corn.agronomy.wisc.edu/Management/L041.aspx

http://corn.agronomy.wisc.edu/Management/L041.aspx

http://books.google.com.au/books?id=1wzLYE4HQJIC&pg=PA40&lpg=PA40&dq=MAIZE+AND+FROST&source=bl&ots=oOG_5cHMV6&sig=cOsKqPlAl7jxXaSM2kS83YmepNM&hl=en&sa=X&ei=qgE-VKGDCcjwoATvzYHwDQ&ved=0CEAQ6AEwBQ#v=onepage&q=MAIZE AND FROST&f=false





http://www.far.org.nz/mm_uploads/60Mz_Sth_Canty_Frosts.pdf




http://www.yara.co.uk/crop-nutrition/crops/maize/crop-nutrition/increasing-maize-resistance-to-lodging-and-frost/




http://www.regional.org.au/au/asa/2012/crop-production/7994_pembletonkg.htm







http://www.utas.edu.au/tia/programs/programs-home/agricultural-production-systems/assessing-frost-risk-for-silage-maize






December 2014



Whenagraincropisfrostedatmilk-line,theyieldswillbereducedby50%unlesssome

leavessurvivedthefrost(Table1).Severelyfrostedcropswillneedtobefield-dried,andthis

willresultinhighfieldlosses,becausemaizethatisfrostedatanimmaturestagetendsto

haveagreaterincidenceofstalkbreakage.Earmouldsmaydevelopwhendryingisslow

andtestweightislikelytobelow.Duringcombining,grainwillbesusceptibletobreakage

andthewetcoremaybreakintoseveralpieces,increasingtheriskofgrainrejectionor

discountingduetobrokengrainandforeignmaterial.Formanycropsthatarefrostedprior

to½milk-line,maizesilageisthebestoption.

Maizegraincropsthatarekilledbyfrostafter½milk-linewillhavereducedyield(Table1)

andtestweightswillbebelownormal.Ifonlyaportionoftheplanttissueiskilledandifthe

grainwasclosetoblacklayer,theyieldlosswillbesmallandtestweightswillbecloserto

normal.

StudiesinMinnesotasimulatingfrostatmilk-line(~55%grainmoisture)indicatedthat

immaturemaizekilledbyafrostdriednormallywhenenvironmentalconditionswere

favourable.Thedrydownwasdelayedforafewdaysafterthefrost,andthisresultedin

4–9moredaystoreachaharvestmoisturelevelof22–30%comparedwithnon-frosted

maize.Thiswilldelayharvestand/orincreasedryingcharges.

Severefrostwillnotaffectgrainyieldorqualityafterphysiologicalmaturity(blacklayer).5

ThisisunlikelyunderAustralianconditions.

14.1.3 Reducing the risk of frost damageTheriskoffrostdamageinautumncanbereducedbyplantingearly.Shortermaturity

hybridsshouldbeusedifplantingisdelayed.Paddockselectionisimportantinfrost-prone

areas.Ifpossible,chooseapaddockthatisslopingand/orhasanortherlyaspect.Avoid

flatpaddockssurroundedbyhigherground. 6

14.2 Waterlogging and flooding issues

Ingeneratingayieldresponsetoappliedwater,itisasimportanttoavoidwaterlogging

stressasitistoavoidstressfrommoisturedeficits.7

Inaddition,lossofnitrogen(N)canresultfromwaterloggingandheavyrains,suchas

thosereceivedinpartsofthenorthernregioninJanuary2013thatresultedinsoilNlosses

of10–20kg/ha,onaverage,throughdenitrificationfromsummermineralisedN.Soiltest

resultsshowedsoilprofileswithlowlevelsofmineralN.

Ifheavyrainswaterlogthesoilduringhotconditionswhensoilnitrateconcentrationsare

high,suchasattheendofafalloworbeforefertiliserNhasbeentakenupbythecrop,

denitrificationlossescanbelargeforsummercropssuchasmaize.




i More information

JILizaso.Evaluatingand

improvingcropsimulation

modelstoassess

theimpactofclimate

change.

WKMasonet al.(1987)

Effectsofearlyseason

waterlogging on maize

growthandyield.

Australian Journal of

Agricultural Research 38.

HWaqas.Waterlogging

a seriousproblemfor

thegrowthofmaize(Zea

maysL.).








http://docs.agrisafe.eu/training3/Lizaso.pdf





http://www.publish.csiro.au/paper/AR9870027.htm






http://www.academia.edu/6809468/Water_Logging_a_Serious_Problem_for_the_Growth_of_Maize_Zea_mays_L._






December 2014



InJanuaryandFebruary2013,trialsatTamworthandQuirindi,NewSouthWales,showed

significantlossesofnitrousoxidefromcropssownlatein2012thatexperiencedlittleearly

rainaftersowing.

OthertrialsatTamworthshowedthatsignificantdenitrificationoccurredinsummerafter

post-harvestmineralisationofN-richcropssuchaschickpeasandcanola.8

14.2.1 Effects on the maize root systemEffectsofsoildroughtorwaterloggingonmorphologicaltraitsoftherootsystemand

internalrootanatomyoftheseminalroothavebeenstudiedinmaizehybridsofdifferent

droughttolerance.Theresultsdemonstratedabroadvariationinthehabitoftheroot

systemandinsomeanatomicalproperties.9

Plantsgrownunderwaterloggingordroughtconditionsshowedasmallernumber

andlessdrymatteroflateralbranchingrootsthanplantsgrownincontrolconditions.

Waterloggingwasmoreharmfultothegrowthofrootsandhadagreatereffectoninternal

rootanatomicalcharacteristicsthandrought.Theobservedeffectsofbothtreatmentswere

greaterindrought-sensitivehybridPioneerDthanindrought-resistanthybridPioneerC.

PioneerChadmoreextensiverootingandsmalleralterationsinrootmorphologycausedby

thestressconditions.Differencesbetweentheresistantandsensitivemaizehybridswere

apparentfortheexaminedrootanatomicaltraits.ResultsconfirmthatthehybridPioneerD,

withhighdroughtsusceptibility,wasalsomoresensitivetoperiodicsoilwaterexcess.More

efficientwateruseandalowershoottorootratiowerefoundtobemajorreasonsforthe

higherstressresistanceofthehybridPioneerC.

Thedifferentresponseoftheexaminedhybridstotheconditionsofdroughtorwaterlogging

maybeexplainedbyamoreeconomicalwaterbalanceandmorefavourablerelations

betweentheshootandrootdimensionsinthedrought-resistantgenotype.Theobserved

modificationsoftheinternalrootstructurecausedbywaterdeficitinplanttissuesmay

influencewaterconductivityandtransportwithinroots.

Morphologicalandanatomicaltraitsofthemaizerootsystemmaybeusedasselection

criteria in maize breeding. 10

8 TDixon(2014)DenitrificationthelatestchapterintheNstory.GroundCoverIssue108,Jan.Feb.2014,GRDC,http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-108-Jan-Feb-2014/Denitrification-the-latest-chapter-in-the-N-story

9 SGrzesiak,TSura,MTGrzesiak,SPieńkowski(1999)Theimpactoflimitedsoilmoistureandwaterloggingstressconditionsonmorphologicalandanatomicalroottraitsinmaize(Zea maysL.)hybridsofdifferentdroughttolerance.Acta. Physiologiae Plantarum21,305–315,http://link.springer.com/article/10.1007%2Fs11738-999-0046-4

10 SGrzesiak,TSura,MTGrzesiak,SPieńkowski(1999)Theimpactoflimitedsoilmoistureandwaterloggingstressconditionsonmorphologicalandanatomicalroottraitsinmaize(Zea maysL.)hybridsofdifferentdroughttolerance.Acta. Physiologiae Plantarum21,305–315,http://link.springer.com/article/10.1007%2Fs11738-999-0046-4

i More information

YZ Liu et al.(2010)

Screeningmethodsfor

waterlogging tolerance

atmaize(Zea mays

L.)seedlingstage.

Agricultural Sciences in

China 9.

SGrzesiaket al.

(1999)Theimpact of

limitedsoilmoisture

and waterlogging

stressconditionson

morphologicaland

anatomicalroottraits

inmaize(Zeamays

L.)hybridsofdifferent

droughttolerance.

B Ren et al.(2014)

Effectsofwaterlogging

ontheyieldandgrowth

of summermaize

underfieldconditions.

CanadianJournalof

Plant Science 94.

Optimisingmaizeyield

underyieldunder

irrigation.GRDCUpdate

PapersSeptember2008.

KPenfold(2009)Big

decisionsreshaping

thecottonlandscape.

GroundCoverIssue82.

TDixon(2014)

Denitrificationthelatest

chapterintheNstory.

Ground CoverIssue108.

CBirchet al.(2006)

Architecturalmodelling

of maize under water

stress.MaizeAssociation

ofAustralia.


http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-108-Jan-Feb-2014/Denitrification-the-latest-chapter-in-the-N-story


http://link.springer.com/article/10.1007%2Fs11738-999-0046-4




http://www.sciencedirect.com/science/article/pii/S167129270960105X

















http://pubs.aic.ca/doi/abs/10.4141/cjps2013-175











https://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-82-September-October-2009/Big-decisions-reshaping-the-cotton-landscape








http://www.maizeaustralia.com.au/events_files/Architectural modelling of maize - CJ Birch.pdf





Section 15 MAIZE - Marketing


December 2014



SECTION15

Marketing

Maizeisrenownedforitsflexibilityandvarietyofenduses;however,itremainsnecessary

formaizegrowerstoplantheirmarketingstrategieswellinadvance,becausedemandfor

Australianmaizereliesheavilyondomesticmarkets.Allmaizesurplustotherequirements

ofhumanconsumptionmarketsmustbevaluedagainstotherfeedgrainssuchwheat,

barleyand,inparticular,sorghum.Proximitytomarketshasamajorinfluenceonprofitability,

particularlyofsilage.

Theprocessorsofmaizegrainforthehumanconsumptionmarketshavestringent

guidelinesthatmustbeunderstoodbygrowersenteringtheindustry.Forwardcontractsare

usedextensivelybyprocessorstoensurereliabilityofsupplyandgrainquality.Contracts

mayoutlinethehybridstobegrown,whichmaynotnecessarilybethehighestyielding

linesfortheregion;however,premiumsmaybeofferedbasedonquality.Traditionalmaize

growerstendtobeofferedcontractsaheadofnewgrowers,makinginitialcontractsdifficult

toattain.Inmostirrigationareas,itisconsideredhighrisktoplantamaizecropwithouta

major portion under contract.

Figure 1: It is important for maize growers to plan marketing in advance. (Photo: Nicole Baxter)

Thepopcornmarketisespeciallysmallandvolatile,andassuch,allproductisbought

domesticallyundercontract.




December 2014



Forwardcontractingisalsocommoninthedairyandfeedlottingindustriesforthepurchase

ofmaizesilage.Contractswillspecifyquantityandqualityparametersandthedateof

delivery.Growersmustconsidertheriskofcropcontaminationfromspraydriftwhen

growingmaizeundercontract,becausedetectionofresidueswillresultinproductrejection.

Usually,thegrowerorganisesharvestandtransport,whichispaidforbythebuyer.

15.1 Preventing mycotoxin contamination

Mycotoxinsaretoxicchemicalsthatcanbeproducedbysomefungiwhentheyinfect

maize.Mycotoxinsareassociatedwithdiseasesinhumans,petsandlivestock,andso

theirpresenceinmaizeisregulatedindomesticandinternationalmarkets.Australian

maizeingenerallyofhighqualitywithregardtomycotoxincontaminationcomparedwith

otherexportingcountries,yettherehavebeenrecenttradeproblems,withcontainersof

maizefailingtomeetmycotoxinstandardsuponarrival.Itisunclearwhethercontamination

occurredatthesourceorduringstorageandtransport.Despiteonlyasmallpercentageof

Australianmaizeeverhavingbeenaffected,theseincidentshavehighlightedtheneedfor

anindustry-wideapproachtoensurethatAustralianmaizemeetsthestandardsofallend-

users.

TheMaizeAssociationofAustraliaisestablishingsupplychainandexportprotocolsto

enhancethereputationofAustralianmaize.Theprotocolshighlightstepsthatshouldbe

takenbyexporterstoensurethatshipmentsmeetinternationalstandards. 1

15.2 Marketing

15.2.1 GrainSellingisdonethroughnormalmerchantchannelsorundercontracttomillers,starch

manufacturers,orcornchiporbreakfastcerealmanufacturers.Pricepremiumsapply

forgrainofvariousprocessingqualities.Thefeedmarkettendstohavelowerprices,but

enjoysmuchmoreflexibilitywithregardtotherangeofhybridsused,allowinggrowersto

makeuseofhigheryieldinghybrids. 3

15.2.2 Marketing silageSilagemaizeisnormallysolddirecttofeedlotsanddairiesatanagreedpricepertonne

in-field.Farmersgrowingforstockfeedgrainandsilageneedtobeawareofthestringent

requirementofmostbuyersinrelationtochemicalresidues. 4


2 NMoore,LSerafin,LJenkins(2014)Summercropproductionguide2014.NSWDPIManagementGuide.NSWDepartmentofPrimaryIndustries,NSWDPISummerCropProductionGuide2011http://www.dpi.nsw.gov.au/agriculture/broadacre/guides/summer-crop-production-guide

3 DAFF(2012)Harvestingandmarketingformaize.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/harvesting-marketing


i More information

GrainTradeAustralia

(2013)MaizeStandards.

2013/13season.

i More information

Go to MaizeAssociation

ofAustralia to download

supplychainandexport

protocols,togetherwith

detailed information on

howtoreducetherisk

ofcontaminationwhen

growing maize. 2








http://www.graintrade.org.au/sites/default/files/file/Commodity Standards/Section 02 - Maize Standards 201314 Final.pdf







December 2014



15.2.3 Drying corn for the gritting millersHairline(stress)crackingofcornkernelsmustbewithinlimitsprescribedbymillers.Stress

cracksarecracksintheclearendosperminsidethekernel,whichdonotrupturetheseed

coat.

Thefollowingpointsondryingmayalsohelpgrowerstominimisestresscrackingand

obtainhighgritting-qualitycorn:

• Startinggrainmoisturelevels>17.5%makedryingveryriskyforhairlinecracking.

• Ensurethatgraintemperaturedoesnotexceed38°Cduringdrying.

• Coolthedriedgrainslowly.Avoidusingblowersongrainafterdryingoncool,windy

days.Drygrainearlyinthedaytoenableslowcoolingasthedaytemperatureslowly

decreases.Dryinggrainunderheatuntillateafternoonwillmeanthatthehotgrainis

toorapidlycooled,oftenresultinginexcessivecracking.

• Donotleavegrainuncoveredovernightinfieldbinsoropendryers.Rainordewwill

predisposesurfacegraintocracking.

• ‘Dryeration’andcombinationdryingsystemsminimisestresscracking.Dryeration

involvesarapidinitialdryingfollowedby6–10hoftemperingtorelievestresses,then

afinalcoolingperiod.Combinationortwo-stagedryingusesafirstphaseofhigh-

temperature,high-speeddrying,followedbyasecondfinaldryingwithambientor

low-temperature air. 5

15.3 Maize Association of Australia (MAA)

TheMAAwasestablishedin1991andaimstoaddresstheneedsofallsectorsofthe

Australianmaizeindustry.TheaimsoftheMAAareto:

• promotetheexchangeofideas,knowledge,innovationandcooperationofallpartiesin

themaizeindustry,fromprimaryproducertoexporter;

• supporttheproduction,developmentandmarketingofmaizeproducts;

• increasetheawarenessofmaize,itsusesanditsbyproducts;and

• increasethecommunicationbetweengrowersandend-userstopromoteandincrease

themanyusesofmaize.


i More information

SClarry(2013)Asian

buyersliftdemandfor

maize. GRDC Ground

CoverIssue103.

TCogswell(2012)

Australianmaizeindustry

overview—2012.GRDC

UpdatePapers.

GRDC—Driving

AgronomyPodcasts.

i More information

MaizeAssociationof

Australia.



http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-103-Mar-April-2013/Asian-buyers-lift-demand-for-maize




http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2012/08/Australian-maize-industry-overview-2012




https://itunes.apple.com/au/podcast/grdc-driving-agronomy-podcasts/id602879089?mt=2

https://itunes.apple.com/au/podcast/grdc-driving-agronomy-podcasts/id602879089?mt=2



Section 16 MAIZE - Current research


December 2014



SECTION16

Current research

Soon to be populated.


Section 17 MAIZE - Key contacts


December 2014



SECTION17

Key contacts

James Clark - Chair

HunterValleygrowerJamesbringsextensiveknowledgeand

experienceindrylandandirrigatedfarmingsystemstothe

NorthernPanel.Hehasbeenamemberofthepanelsince2005

andchairmansince2008.Jamessaysthepanel’sroleisto

captureandinvestingrowers’prioritiesandempowerthemto

adoptnewproductiongainopportunities.Hestronglybelieves

thegrainsindustryneedstocontinuebuildingRD&Ecapacityto

ensuregrowersremaincompetitive.

M 0427 545 212

[email protected]

Loretta Serafin - Deputy Chair

Lorettahasmorethan12years’experienceasanagronomist

innorth-westNSWandcurrentlyworkswiththeNSWDPIin

Tamworth.Sheisatechnicalspecialistfornorthernfarming

systemsandprovidesexpertiseandsupporttogrowers,industry

andagronomistsintheproductionofsummercrops.Shehasa

passionforhelpinggrowersimprovefarmefficiencyandseesher

roleasaconduitbetweenadvisers,growersandtheGRDCto

ensurethatgrowers’needsarebeingmet.

M 0427 311 819

[email protected]

John Sheppard

John,apanelmembersince2006,hasawealthofpractical

farmingexperienceandbringsawheatbreeder’sperspective

tothepanel.Heviewsthepanelasanopportunityforgrowers

andprofessionalstoworktogethertoshapethefutureofthe

industry,anddevelopbestmanagementpractices,aswellasnew

varietiesandproducts.Heisparticularlyinterestedingenotype-by-

environmentinteractionandthepreservationofgeneticresources.

M 0418 746 628

[email protected]


mailto:colane%40bigpond.com?subject=

mailto:loretta.serafin%40dpi.nsw.gov.au?subject=

mailto:moorkulla%40gmail.com?subject=



December 2014



Jack Williamson

Jack,aprivateagriculturalconsultant,runsabroadacrecommodity

productionfarminGoondiwindi.Previousrolesasaterritorysales

managerforNufarmandasacommercialagronomistforMcGregor

GourlayAgriculturalServiceshavegivenJackextensivefarming

systemsknowledge,anddiversecropmanagementandfieldwork

experience.JackisamemberoftheNorthernGrowerAlliance

(NGA)localconsultativecommitteandCropConsultantsAustralia,

andwaspreviouslypresidentoftheMacIntyreValleyCottonField

DayCommittee.

M 0438 907 820

[email protected]

Julianne Dixon

JulesismanagerofAMPSResearchandapassionateagronomy

consultant,communicatorandindustryadvocate.Herrole

involvesthedevelopmentandexpansionofself-funded,privatised

research,developmentandextension.Herexperienceinproject

managementandstrategicdevelopmentextendsacrossallfacets

ofanintegratedgrainsbusiness.Shehasanestablishednetwork

ineasternAustraliaandWesternAustralia,includingresearchers,

leadinggrowers,agronomyconsultantsandcommercialindustry.

M 0429 494 067

[email protected]

Keith Harris

KeithhasservedontheNorthernPanelsince2011andbrings

morethan30years’experienceinpropertymanagement.Keith,

basedontheLiverpoolPlains,NSW,consultstoRomaniPastoral

Companyonthemanagementofitshistoricholdings‘Windy

Station’and‘Warrah’,nearQuirindi.Heseesthemainaimof

thepanelasrepresentinggrowersandconductingresearchthat

providesgrowerswiththetoolstheyneedtomaximiseproperty

performanceandminimiserisk.

M 0428 157 754

[email protected]


mailto:jack.williamson1%40bigpond.com?subject=

mailto:juliannedixon%40bigpond.com?subject=

mailto:kharris%40romanipastco.com.au?subject=



December 2014



Kelly Becker

BasedatTheodore,Queensland,Kellyisacertifiedmungbeanand

chickpeaagronomistandalsoadvisesgrowersonwheat,corn

andsorghumcropproduction.Shehasbeeninvolvedwithvariety

trialsonacommercialbasisandindustryfarmpracticetrialsas

anagronomist.Shestrivestobeproactivewithintheindustryand

aimstoassistgrowerstoimprovefarmingoperationsbyensuring

thattheyareuptodatewithnewpracticesandtechnology.

M 0409 974 007

[email protected]

Penny Heuston

Pennybringsextensiveexperiencetohersecondtermonthe

NorthernPanel.Sheiscommittedtomaximisingtheprofitabilityof

grainproductioninalow-rainfallenvironmentthroughincreased

productivityandgoodriskmanagementpractices.Shewas

principalinafarmadvisorybusinessincentralwestNSWand

workedwithgrowersacrossnorth-westNSWbeforejoining

DeltaAgribusiness,wherehermainfocusistheWarren,Nyngan,

TottenhamandGilgandraareas.

M 0428 474 845

[email protected]

Rob Taylor

RobisagraingroweratMacalisteronQueensland’sDarling

Downsandfarms2300hectaresofmaize,sorghum,wheat,barley

andchickpeasontheJimbourPlain.Robiscurrentlychairofthe

AgrifoodSkillsInitiativefortheWesternDownsRegionalCouncil

area.Robviewshisroleonthepanelastakinginformationand

feedbackfromgrowers,advisersandresearcherstotheGRDCto

ensureresearchistargeted.

M 0427 622 203

[email protected]

Will Martel

CentralNSWgrowerWillhasservedontheNorthernPanelsince

2011.PreviouslyheworkedinaQuirindigraintradingcompany

andwithBrisbane-basedResourceConsultingServices(RCS)

wherehebenchmarkedmorethan400growersacrossAustralia

ontheirperformance,focusingonwhole-farmprofitabilityrather

thanindividualenterprisegrossmargins.Hismainroleonthepanel

isidentifyinginvestmentareasthatwillenablegrowerstoremain

economicandenvironmentallysustainable.

M 0427 466 245

[email protected]


mailto:kbecker19%40bluemaxx.com.au%20?subject=

mailto:pennyheuston%40deltaag.com.au?subject=

mailto:currfarm%40ozxpress.com.au%20?subject=

mailto:wandgmartel%40bigpond.com.au%20?subject=



December 2014



Dr Stephen Thomas - GRDC Executive Manager Commercial

BeforejoiningtheGRDCSteveheldaseniorpositionwiththeNSW

DepartmentofPrimaryIndustriesatOrange.Inearly2009hewas

appointedexecutivemanagerpracticesattheGRDCandin2011

wasappointedexecutivemanagerresearchprograms.Currently

Steveholdsthepositionofexecutivemanagercommercial.He

seestheGRDC’sroleistointeractwithgrowersregularlyto

determinetheirneedsandfocusonthebigpictureacrossentire

farmingsystems.

T 02 6166 4500

[email protected]

Sharon O’Keeffe - GRDC Northern Regional Manager

SharonistheNorthernRegionalManagerfortheGrains

ResearchDevelopmentCorporation(GRDC),basedinBoggabri

NSW.Sharon’sroleistoidentifyandoverseeregionalresearch,

developmentandextension(RD&E)needs,managetheregional

deliveryofinformationandpromotetheGRDC’sproductsand

services.HerrolestrengthenslinksbetweenGRDCpanels,

researchers,industry,advisorsandgrowers.Sharonholdsa

MastersinAgricultureandaBachelorofRuralScience(hons).

M 0409 279 328

E:[email protected]

David Lord - Panel Support Officer

DavidoperatesagriculturalconsultancyLordAgConsulting.Forthe

pastfouryearshehasworkedasaprojectofficerforIndependent

ConsultantsAustraliaNetwork(ICAN),whichhasgivenhimagood

understandingoftheissuesgrowersarefacinginthenorthern

grainsregion.David’snewroleisNorthernPanelandRegional

GrowerServicessupportofficer.

M 0422 082 105

[email protected]


mailto:steve.thomas%40grdc.com.au%20?subject=

mailto:sharon.okeeffe%40grdc.com.au?subject=

mailto:northernpanel%40gmail.com%20?subject=

Section 18 MAIZE - References


December 2014



SECTION18

References

A: IntroductionAustralianBureauofStatistics(2013)HistoricalSelectedAgricultureCommodities,byState(1861to

Present),(cat.no.7124.0).AustralianBureauofStatistics,http://www.abs.gov.au/AUSSTATS/[email protected]/mf/7124.0

AustralianBureauofStatistics(2014)7121.0-AgriculturalCommodities,Australiaand7503.0-ValueofAgriculturalCommoditiesProduced.AustralianBureauofStatistics,http://www.abs.gov.au/AUSSTATS/[email protected]/DetailsPage/7121.02012-2013?OpenDocument and http://www.abs.gov.au/AUSSTATS/[email protected]/mf/7503.0

DAFF(2012)MaizeproductioninQueensland.DepartmentofAgriculture,FisheriesandForestryQueensland.http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize

Dentcorn.Wikipedia,http://en.wikipedia.org/wiki/Dent_corn

Flintcorn.Wikipedia,http://en.wikipedia.org/wiki/Flint_corn

NMoore,LSerafin,LJenkins(2014)Summercropproductionguide2014.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/agriculture/broadacre/guides/summer-crop-production-guide

KO’Keeffe(2009)Maizegrowthanddevelopment,PROCROPSeries,NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0007/516184/Procrop-maize-growth-and-development.pdf

PacificSeeds(2008/2009)Hybridcornagronomyguide2008/09,PacificSeedsPtyLtd,http://cairo.directrouter.com/~pacseeds/images/stories/corn/information/cornagronomy08.pdf

PioneerHi-BredAustralia.Growthpotential.Corngrowersworkshop.http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Corn_Workshop_Book.pdf

Section 1: Planning and paddock preparationAustralianCliMate—Climatetoolsfordecisionmakers,www.australianclimate.net.au

KBecker(2014)Plannowforsummerdoublecrop.GRDCMediaCentreOctober2014,http://www.grdc.com.au/media-centre/media-news/north/2014/10/plan-now-for-summer-double-crops

SBelfield,CBrown(2008)Fieldcropmanual:maize.AguidetouplandproductioninCambodia.CambodianAgriculturalResearchandDevelopmentInstituteandNSWDepartmentofPrimaryIndustries,http://aciar.gov.au/files/node/8919/maize%20manual%2072dpi.pdf

Corn and cotton rotation. Du Pont Pioneer, http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Cotton_Corn_Rotation.pdf















http://en.wikipedia.org/wiki/Dent_corn

http://en.wikipedia.org/wiki/Flint_corn

















December 2014



CropWaterUse.MoreProfitperDropIrrigatedFarmingSystems,http://www.moreprofitperdrop.com.au/irrigation-management/have-you-ever-wondered-how-much-water-a-crop-really-needs/

DAFF(2010)GrowingmaizeinthecoastalWetTropics.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/varieties-planting/growing-maize-in-the-coastal-wet-tropics#Paddock_selection

DAFF(2011)Howtorecogniseandmonitorsoilinsects.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/help-pages/recognising-and-monitoring-soil-insects

DAFF(2012)Nutrition,irrigationandweedsformaize.DepartmentofAgriculture,FisheriesandForestryQueensland,https://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/nutrition-irrigtion

ADevereux,SFukai,NRHulugalle(2008)Theeffectsofmaizerotationonsoilqualityandnutrientavailabilityincottonbasedcropping.In14thAustralianAgronomyConference,http://www.regional.org.au/au/asa/2008/concurrent/plant-nutrition/5815_devereuxaf.htm

DPI(2005)Grainsorghum.AgfactP3.3.5.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0006/146355/grain-sorghum.pdf

JFleming,TMcNee,TCook,BManning(2012)Weedcontrolinsummercrops2012–13.NSWDPIManagementGuide.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/agriculture/pests-weeds/weeds/publications/summer

GRDC(2008)Optimisingmaizeyieldunderirrigation.GRDCUpdatePapersSeptember2008,http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2008/09/OPTIMISING-MAIZE-YIELD-UNDER-IRRIGATION

GRDC(2012)Makesummerweedcontrolapriority.Summerfallowmanagement.Southernregion.GRDCFactSheetJanuary2012,http://www.grdc.com.au/Resources/Factsheets/2012/01/Summer-Fallow-Management-Southern-Region-Fact-Sheet

RHuang,CJBirch,DLGeorge(2006)Wateruseefficiencyinmaizeproduction—thechallengeandimprovementstrategies.In6thTriennialConference,MaizeAssociationofAustralia,http://www.maizeaustralia.com.au/events_files/Water%20use%20efficiency%20in%20maize%20-%20CJ%20Birch.pdf

NMoore,LSerafin,LJenkins(2014)Summercropproductionguide2014.NSWDPIManagementGuide.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/agriculture/broadacre/guides/summer-crop-production-guide

KOwen,TClewett,JThompson(2013)Summercropdecisionsandrootlesionnematodes.GRDCUpdatePapers16July2013,http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/07/Summer-crop-decisions-and-root-lesion-nematodes

KOwen,JSheedy,NSeymour.Rootlesionnematode—Queensland.SoilQualityPtyLtdFactSheet,http://www.soilquality.org.au/factsheets/root-lesion-nematode-in-queensland


QueenslandPrimaryIndustriesandFisheries(2009)Root-lesionnematodes—managementofroot-lesionnematodesinthenortherngrainregion.QueenslandGovernment,http://www.daff.qld.gov.au/__data/assets/pdf_file/0010/58870/Root-Lesion-Nematode-Brochure.pdf































December 2014



BRaymond,GHarris.Irrigatedcorn—bestpracticeguide.InIrrigatedmanagementofgraincrops.WATERpak—aguideforirrigationmanagementincottonandgrainfarmingsystems,http://www.moreprofitperdrop.com.au/wp-content/uploads/2013/10/WATERpak-4_3-Irrigated-Corn-best-practice.pdf

D Rodriguez et al.(2013)Relay-croppingextendscroppingwindow.GroundCoverIssue104,May2013. GRDC, http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-104-May-June-2013/Relay-cropping-extends-cropping-window

JSabburg,GAllen(2013)Seasonalclimateoutlookimprovementschangesfromhistoricaltorealtimedata.GRDCUpdatePapers18July2013,http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/07/Seasonal-climate-outlook-improvements-changes-from-historical-to-real-time-data

TheCob,August2011.MaizeAssociationofAustralia,http://www.maizeaustralia.com.au/cob_files/autumncob2011.pdf

Section 2: Pre-plantingDAFF(2012)Nutrition,irrigationandweedsformaize.DepartmentofAgriculture,FisheriesandForestry

Queensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/nutrition-irrigtion

DAFF(2012)Varietiesandplantingofmaize.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/varieties-planting

MBMcDonald(1998)Seedqualityassessment.SeedScienceResearch8,265–276,http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1356024&fileId=S0960258500004165


Section 3: PlantingDAFF(2012)Varietiesandplantingofmaize.DepartmentofAgriculture,FisheriesandForestry

Queensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/varieties-planting

Earlypestofsorghumandmaize.AgronomyTopics.PacificSeeds,http://www.pacificseeds.com.au/info-and-tools/agronomy-topics/78-early-pest-of-sorghum-and-maize.html


PacificSeeds(2008/2009)Hybridcornagronomyguide2008/09.PacificSeedsPtyLtd,http://cairo.directrouter.com/~pacseeds/images/stories/corn/information/cornagronomy08.pdf

AMSmith(1970)Effectoffungicidesonthegerminationofmaizeseedafterstorage.Australian Journal of Experimental Agriculture and Animal Husbandry10174–175,http://www.publish.csiro.au/paper/EA9700174.htm





























December 2014



Section 4: Plant growth and physiologyGrowthpotential.Corngrowers’workshop.PioneerHi-BredAustralia.http://www.pioneer.com/

CMRoot/International/Australia_Intl/Publications/Corn_Workshop_Book.pdf

KO’Keeffe(2009)Maizegrowth&development.PROCROPSeries,NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0007/516184/Procrop-maize-growth-and-development.pdf

Section 5: Nutrition and fertiliserDAFF(2010)Nutrition—VAMandlongfallowdisorder.DepartmentofAgriculture,FisheriesandForestry

Queensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/nutrition-management/nutrition-vam

DAFF(2012)Nutrition,irrigationandweedsformaize.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/nutrition-irrigtion

Growthpotential.Corngrowers’workshop.PioneerHi-BredAustralia.http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Corn_Workshop_Book.pdf



Section 6: Weed controlMCongreve(2014)Managingherbicideresistantweedsinthesummerfallow.GRDCUpdatePapers

July2014,http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2014/07/Managing-herbicide-resistant-weeds-in-the-summer-fallow

DAFF(2012)Nutrition,irrigationandweedsformaize.DepartmentofAgriculture,FisheriesandForestry,Queensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/nutrition-irrigtion

JFleming,TMcNee,TCook,BManning(2012)Weedcontrolinsummercrops2012–13.NSWDPIManagementGuide.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0008/248471/Weed-control-in-summer-crops-2012-13.pdf

Growthpotential.Corngrowers’workshop.PioneerHi-BredAustralia,http://www.pioneer.com/CMRoot/International/Australia_Intl/Publications/Corn_Workshop_Book.pdf


AStorrie(1997)Australianmaize,KondininGroup.

Section 7: Insect controlK.Charleston(2013)Maizeinsectpestmanagement.Northerngrainsregion.Departmentof

Agriculture,FisheriesandForestryQueensland,http://ipmworkshops.com.au/wp-content/uploads/Maize_IPM-Workshops_north-March2013.pdf


























December 2014



DAFF(2012)Insectpestmanagementinmaize.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/ipm-information-by-crop/maize#cropstage

Earlypestofsorghumandmaize.PacificSeeds,http://www.pacificseeds.com.au/info-and-tools/agronomy-topics/78-early-pest-of-sorghum-and-maize.html


Section 8: NematodesGMMurray,JPBrennan(2009)ThecurrentandpotentialcostsfromdiseasesofwheatinAustralia.

GRDC Report, https://www.grdc.com.au/~/media/B4063ED6F63C4A968B3D7601E9E3FA38.pdf

KOwen,TClewett,JThompson(2013)Summercropdecisionsandrootlesionnematodes.GRDCUpdatePapers16July2013,http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/07/Summer-crop-decisions-and-root-lesion-nematodes

KOwen,TClewett,JThompson(2014)Latestnematodesummerandwintercroprotationresults.GRDCUpdatePapers,7March2014,http://grdc.com.au/Research-and-Development/GRDC-Update-Papers/2014/03/Latest-nematode-summer-and-winter-crop-rotation-results

KOwen,JSheedy,NSeymour(2013)RootlesionnematodeinQueensland.SoilQualityPtyLtdFactSheet,http://www.soilquality.org.au/factsheets/root-lesion-nematode-in-queensland

QueenslandPrimaryIndustriesandFisheries(2009)Root-lesionnematodes—managementofroot-lesionnematodesinthenortherngrainregion.QueenslandGovernment,http://www.daff.qld.gov.au/__data/assets/pdf_file/0010/58870/Root-Lesion-Nematode-Brochure.pdf

Section 9: DiseasesPacificSeeds(2008/2009)Hybridcornagronomyguide2008/09,PacificSeedsPtyLtd,http://cairo.

directrouter.com/~pacseeds/images/stories/corn/information/cornagronomy08.pdf

NMoore,LSerafin,LJenkins(2014)Summercropproductionguide.NSWDPIManagementGuide.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/agriculture/broadacre/guides/summer-crop-production-guide

DAFF(2012)Diseasesaffectingmaize.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/diseases

Section 12: HarvestDAFF(2012)Harvestingandmarketingformaize.Maizeproduction.DepartmentofAgriculture,

FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/harvesting-marketing

NMoore,LSerafin,LJenkins(2014)Summercropproductionguide.NSWDPIManagementGuide.NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/agriculture/broadacre/guides/summer-crop-production-guide




























December 2014



Section 13: StoragePBotta,PBurrill,CNewman(2010)Pressuretestingsealablesilos.GRDCGrainStorageFactSheet,

September 2010, http://www.grdc.com.au/~/media/0218DA4A22264A31B6202718043758DE.pdf

PBurrill(2013)GrainStorageFuture:pestcontroloptionsandstoragesystems2013–2014.GRDCUpdate,July2013,http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/07/Grain-Storage-Future-pest-control-options-and-storage-systems-2013-2014

PBurrill,PBotta,CNewman(2010)Aerationcoolingforpestcontrol.GRDCGrainStorageFactSheet,September 2010, http://www.grdc.com.au/~/media/AB8938CFDCCC4811AD218B45C308BEBD.pdf

PBurrill,PBotta,CNewman,BWhite,CWarrick(2013)Northernandsouthernregionsstoredgrainpests—Identification.GRDCGrainStorageFactSheet,June2013,http://www.grdc.com.au/GRDC-FS-StoredGrainPestID

PBurrill,PBotta,CNewman,BWhite,CWarrick(2013)Northernandsouthernregions—Grainstoragepestcontrolguide.GRDCGrainStorageFactSheet,June2013,http://www.grdc.com.au/GRDC-FS-GrainStoragePestControl

PBurrill,PBotta,CNewman,BWhite,CWarrick(2013)Dealingwithhigh-moisturegrain.GRDCGrainStorageFactSheet,June2013,http://www.grdc.com.au/~/media/36D51B725EF44EC892BCD3C0A9F4602C.pdf

PBurrill,ARidley(2012)Performancetestingaerationsystems.GRDCResearchUpdateNorthernRegion,Spring2012,Issue66,http://www.grdc.com.au/~/media/DAF5F438D9644D90B9A4FA9716B2014E.pdf

PBurrill,ARidley(2012)Silobagfumigation.GRDCResearchUpdateNorthernRegion,Spring2012,Issue66,http://www.grdc.com.au/~/media/DAF5F438D9644D90B9A4FA9716B2014E.pdf

PCollins(2009)StrategytomanageresistancetophosphineintheAustraliangrainindustry.CooperativeResearchCentreforNationalPlantBiosecurityTechnicalReport,http://www.graintrade.org.au/sites/default/files/file/Phosphine_Strategy.pdf

DAFF(2010)Chemicalstotreatinsectsinstoredgrain.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/grain-storage/chemicals

GTA(2013)WheatStandards,2013/2014season.GrainTradeAustralia,August2013,http://www.graintrade.org.au/sites/default/files/file/Commodity%20Standards/Section%2002%20-%20Wheat%20Standards%20201314.pdf

MNayak(2012)Sulfurylfluoride—Asolutiontophosphineresistance?GRDCResearchUpdateNorthernRegion,Spring2012,Issue66,http://www.icanrural.com.au/newsletters/NL66.pdf

NSWDepartmentofPrimaryIndustriesDistrictAgronomists(2007)Wheatgrowthanddevelopment.PROCROPSeries,NSWDepartmentofPrimaryIndustries,http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0006/449367/Procrop-wheat-growth-and-development.pdf

CNorwood(2013)Geneticcluetothwartphosphineresistance.GRDCGroundCover,Issue102,Jan.–Feb.2013,http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-102/Genetic-clue-to-thwart-phosphine-resistance

CWarrick(2011)Fumigatingwithphosphine,otherfumigantsandcontrolledatmospheres.Doitright—doitonce:AGrainsIndustryGuide.GRDCStoredGrainProject,January2011(reprintedJune2013),http://www.grdc.com.au/~/media/FC440FBD7AE14140A08DAA3F2962E501.pdf





















http://www.graintrade.org.au/sites/default/files/file/Commodity%20Standards/Section 02 - Wheat Standards 201314.pdf



http://www.icanrural.com.au/newsletters/NL66.pdf








December 2014



Section 14: Environmental issuesAutumnfrostedmaizecrops.TechnicalInsights.PioneerBrandProducts,http://www.pioneer.co.nz/

maize-grain/product-information/grain-technical-insights/autumn-frosted-maize-crops.html

SBelfield,CBrown(2008)Fieldcropmanual:maize.AguidetouplandproductioninCambodia.CambodianAgriculturalResearchandDevelopmentInstituteandNSWDepartmentofPrimaryIndustries,http://aciar.gov.au/files/node/8919/maize%20manual%2072dpi.pdf

TDixon(2014)DenitrificationthelatestchapterintheNstory.GroundCoverIssue108,Jan.Feb.2014, GRDC, http://www.grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-108-Jan-Feb-2014/Denitrification-the-latest-chapter-in-the-N-story


SGrzesiak,TSura,MTGrzesiak,SPieńkowski(1999)Theimpactoflimitedsoilmoistureandwaterloggingstressconditionsonmorphologicalandanatomicalroottraitsinmaize(Zea mays L.)hybridsofdifferentdroughttolerance.Acta. Physiologiae Plantarum21,305–315,http://link.springer.com/article/10.1007%2Fs11738-999-0046-4

Section 15: MarketingNMoore,LSerafin,LJenkins(2014)Summercropproductionguide2014.NSWDPIManagement

Guide.NSWDepartmentofPrimaryIndustries,NSWDPISummerCropProductionGuide2011http://www.dpi.nsw.gov.au/agriculture/broadacre/guides/summer-crop-production-guide

DAFF(2012)Harvestingandmarketingformaize.DepartmentofAgriculture,FisheriesandForestryQueensland,http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/maize/harvesting-marketing














GRDC GrowNotes Northern Maize December 2014

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