Read the Sunflower Production Guide

The Sunflower Production Guide


TABLE OF CONTENTS

Acknowledgements 2

SunflowerIndustryProfile 3

INTRODUCTION

›GrowthStages 4

›FieldSelection 6

›Fertilizer 6

›Seeding 9

›FieldScouting 11

›Tillage 12

›Harvesting 12

Pest Management

Integrated Pest Management 13

Insects 14

›SeedlingandRootFeeders 15

›Wireworms 15

›Cutworms 16

›SunflowerBeetle 17

›ThistleCaterpillar 19

›InsectsintheStem 20

›SunflowerBudMoth 20

›SunflowerStemWeevils 22

›SunflowerMaggots 24

›InsectsontheHeads 26

›SunflowerMidge 26

›SunflowerSeedWeevils 28

›BandedSunflowerMoth 30

›LygusBugs 32

›BeneficialInsects 34

Diseases 37

›EarlySeasonDiseases 37

›DownyMildew 37

›FoliarDiseases 39

›Rusts 39

›AlternariaLeaf andStemSpot 41

›Septoria 42

›StalkandRoot-InfectingDiseases 42

›SclerotiniaWilt andBasalRot 42

›SclerotiniaMid-StalkRot 44

›PhomaBlackStem 45

›PhomopsisStemCanker 46

›VerticilliumLeafMottle 47

›HeadRotandDiseasesof MaturePlants 48

›SclerotiniaHeadRot 48

›Rhizopus 49

Blackbirds 50

Weeds 51

›Cocklebur 51

›BiennialWormwood 52

›CanadaThistle 53

›Kochia 54

›PrairieSunflower 55

›Wild-Buckwheat 56

›RedrootPigweed 57

›FalseRagweed 58

›GreenandYellowFoxtail 59

References 60


A|XXX

ACKNOWLEDGEMENTS

PHOTOGRAPHS:

Crop Staging A.A.SchneiterandJ.F.Miller,NorthDakotaStateUniversity

Insects JohnGavloski,ManitobaAgriculture,FoodandRuralInitiativesJanKnodel,NDSUExtensionService,DepartmentofEntomology

Diseases ThomasGulya,UnitedStatesDepartmentofAgricultureSamMarkell,NorthDakotaStateUniversity

Weeds NasirShaikh,ManitobaAgriculture,FoodandRuralInitiatives

ThisguidewasfundedinpartbytheCanadaandManitobagovernmentsthroughGrowing Forward,afederal-provincial-territorialinitiative.

2|Acknowledgements


XXX|A

SUNFLOWER INDUSTRY PROFILE

TheNationalSunflowerAssociationofCanada(NSAC),Inc.wasinitiatedatameetinginCarman,MBonNovember18,1996.ThemeetingwasorganizedtoaddresstheclosureofthesunfloweroilcrushingplantinAltona,MBin1995causingsunfloweracreagetodropfromahighofmorethan300,000acresduringthe1980’sto63,000acresin1995.Theacreagealsoshiftedtoconfectiontypes,promotedbyprocessorslocatedthroughoutManitoba’sRedRiverValleyandsouthernAlberta.

Theassociation’smissionstatementis“toinsuretheprofitabilityandlongtermgrowthofthesunflowercropthroughindustrywideleadership”.Membershipincludesproducers,oilandconfectiontypebuyers,exportersandprocessors,pesticidemanufacturersanddealerswithintheseedindustry.SincetheestablishmentoftheNSACin1996,sunfloweracreagehasclimbedto180,000acresin2008.In2011theassociationhadapproximately650membersfromManitoba,Saskatchewan,andAlberta.

Approximately90percentofallsunflowersgrowninCanadaarelocatedinManitoba,butagrowingshareisfindingitswayintosoutheasternSaskatchewan,southernAlbertaandsouthernOntario.OfallCanadiansunflowers,65percentareconfectiontypeswhicharemarketedprimarilyasroastedsnackfoodintheshellorasdehulledseedsforthebakingindustry.Althoughasignificantpercentageofthismarketisdomestic(NorthAmerica),CanadianprocessorsareincreasinglyaccessingmarketsinEurope,theMiddleEastandAsia.Oilseedsunflowersareusedinboththebirdfoodandthecrushingindustryforsunfloweroilproducingoneofthehighestqualityvegetableoils.Althoughthebirdfoodmarketismostlytheoilseedtype,someofthesmallerconfectionseedsarealsousedforbirdseed.

SunflowerIndustryProfile|3


4|GrowthStages

INTRODUCTION

GROWTH STAGES

Thetotaltimerequiredfordevelopmentofasunflowerplantandthetimebetweenthevariousstagesofdevelopmentdependsonthegeneticbackgroundoftheplantandthegrowingenvironment.Theaveragedevelopmentofalargenumberofplantsshouldbeconsideredwhendeterminingthegrowthstageofasunflowerfield.Laterintheseason,forstagesR-7throughR-9,usehealthy,disease-freeheadstodetermineplantdevelopmentsincesomediseasescancauseheaddiscoloration.Anumberorrecentlyreleasedandgrownhybridscontainthestay-greencharacteristic.Ifthischaracteristicispresent,yellowingorbrowningofthebractsmaynotbeanaccurateindicatorofplantmaturity.Maturityistypicallyreachedwithin2200-2300growingdegreedays(Celsius)afterplantingor120-150days.

Table 1. Sunflower growth stages and description

Stage Description

VE Vegetative Emergence Seedling has emerged and the first leaf beyond the cotyledons is less than 4 cm long.

V (number) Vegetative Stages (e.g. V-1, V-2, V-3 etc.)

These are determined by counting the number of true leaves at least 4 cm in length beginning as V-1, V-2, V-3, V-4, etc. If senescence of the lower leaves has occurred, count leaf scars (excluding those where the cotyledons were attached) to determine the proper stage.

R-1 Reproductive Stages The terminal bud forms a miniature floral head rather than a cluster of leaves. When viewed from directly above, the immature bracts have a many-pointed star-like appearance.

R2 The immature bud elongates 0.5 to 2.0 cm above the nearest leaf attached to the stem. Disregard leaves attached directly to the back of the bud.

R3 The immature bud elongates more than 2 cm above the nearest leaf.

R4 The inflorescence begins to open. When viewed from directly above, immature ray flowers are visible.

R5 (decimal) (e.g., R-5.1, R-5.2, R-5.3, etc.)

This stage is the beginning of flowering. The stage can be divided into sub-stages dependent upon the percent of the head area (disk flowers) that have completed or are in flowering. Ex. R-5.3 (30%), R-5.8 (80%), etc.

R6 Flowering is complete and the ray flowers are wilting.

R7 The back of the head has started to turn a pale yellow.

R8 The back of the head is yellow but the bracts remain green.

R9 The bracts become yellow and brown. This stage is regarded as physiological maturity.

From Schneiter, A.A., and J.F. Miller. 1981. Description of Sunflower Growth Stages. Crop Sci. 21:901-903


GrowthStages|5

Figure 1. Stages of sunflower development. (A.A. Schneiter and J.F. Miller)

North Dakota State UniversityFargo, North Dakota 58105

FEBRUARY 1998

A-1145

Stages of Sunfl ower Development

A.A. Schneiter, ProfessorJ.F. Miller, USDA-ARS

D.R. Berglund, Extension Agronomist

Vegetative Stages

R-5.1

R-8 R-9R-7

R-5.5 R-5.9 R-6

True leaf — 4 cm

V-E

V-2

V-4

R-3 R-3 Top View R-4 Top View

R-1 R-2

Reproductive Stages

V-12

R-2 R-3

More than 2cm

Less than 2cm


6|Introduction

FIELD SELECTION

Soils

Sunflowersgrowbestonwelldrained,highwater-holdingcapacitysoilswithanearlyneutralpH(pH6.5-7.5).Theoptimumsoilclassificationsforsunflowersareloam,siltyloamandsiltyclayloamsoils.Sunflowerproductionperformanceonreducedagriculturalcapacitysoilssuchasthoseaffectedbysalinity,droughtpotentialorwetness,isnotideal,butcompareswithofothercommonlygrowncommercialcrops.

Crop rotation

Havingapropercroprotationalsequenceisimportantwithallcrops,includingsunflowers.Extendedcroprotationshelpreducediseaseinoculumloadsinthesoil,allowforherbiciderotation,manageoverwinteringinsectpopulations,weeds,waterusageandfertilitymanagement.

Growerswhodonothaveadequatecroprotation,willlikelybeconfrontedwithoneormoreofthefollowingyield-reducingproblems:

� Diseaseanddisease-infestedfields(e.g.increasedsclerotinia)� Increasedinsectrisk� Increasedpopulationsofcertainweedspecies� Increasedpopulationsofvolunteersunflowers� Soilmoisturedepletion� Allelopathyorphytotoxicityofthesunflowerresiduetothesunflowercrop

FERTILIZERGeneral

Germinatingsunflowerseedsareverysensitivetoseed-placedfertilizer.Starterapplicationsshouldbeplacedawayfromtheseed.Whensunflowersareseededwithrowequipment,allphosphateandpotassiumshouldbesidebanded2"besideand2"belowtheseedduringplanting.Someorallofthenitrogencanalsobesidebanded.Thetotalamountoffertilizermaterialsidebandedshouldnotexceed300lb/ac.

Nitrogenapplicationscanbemadepre-plant,atseeding,post-seeding,side-dressoracombinationofthesemethods.Applicationshouldbetimedsonitrogenisavailableforrapidplantgrowthanddevelopment.Often,itislogisticallyadvantageoustoapplynitrogeninthefall.However,thelongerthetimeperiodbetweenapplicationandplantuse,thegreaterthepossibilityforNloss.Fallapplicationisnotrecommendedinsandysoilssincetheopportunityforleachingismuchgreater.Aside-dressapplicationofNwhenthesunflowerplantsareabout12incheshighisoftenpreferable.


Introduction|7

Phosphateandpotashmaybefallorspringappliedbeforeatillageoperation.Thesenutrientsarenotreadilylostfromthesoilsincetheyattachtothesoilformingonlyslightlysolublecompounds.Phosphoruscanbeappliedpreplant-broadcast,preplantbanded,orbandedatseeding.Bandappliedapplicationsaremostefficient,especiallywhenonlysmallamountsareappliedinfieldslowinavailablephosphorus.Potassiumdeficienciesnormallyonlyoccurinsandysoils.Potassiumthatisbandplacedisabouttwiceasefficientasbroadcastapplications.

Table 2. Nutrient uptake and removal by sunflower in Manitoba studies.

Nutrient Uptake Removal Uptake Removal

lb nutrient for a 2000 lb crop lb nutrient per cwt

Nitrogen (N) 74-122 48-66 3.7-6.1 2.4-3.3

Phosphorus (P2O5) 24-56 18-26 1.2 – 2.8 0.9 – 1.3

Potassium (K2O) 150-172 18-26 7.5 – 8.6 0.9-1.3

Sulphur (S) 8-12 3-4 0.39 – 0.58 0.17-0.22

Calcium (Ca) 54-94 3-4 2.7-4.7 0.15-0.23

Magnesium (Mg) 37-39 6-7 1.86-1.93 0.30-0.36

Fertilizerapplicationsshouldbemadebasedonasoiltest.RecommendationsbasedonsoiltestingweredevelopedbyManitobaAgriculture,FoodandRuralInitiatives(MAFRI)andarelistedinTables3and4.Recommendationsarebasedona0-24"samplefornitrate-nitrogenandsulphate-sulphur.Phosphorusandpotassiumarebasedona0-6"sample.

Table 3. Nitrogen recommendations for sunflower (based on spring band application).

TARGET YIELD (lb)

Fall Soil NO3-N 1750 2,000 2,250 2,500

lb/ac in 0-24" Rating Nitrogen Recommendations (lb/ac)

20 VL 40 85 125 170

30 L 20 60 105 145

40 M 0 35 80 120

50 M 0 10 55 100

60 H 0 0 30 75

70 H 0 0 5 50

80 VH 0 0 0 25

90 VH 0 0 0 0

100 VH+ 0 0 0 0


8|Introduction

Table 4. Phosphorus, potassium and sulphur recommendations for sunflower based on soil test levels and placement.

PHOSPHORUS POTASSIUM SULPHUR

Soil Phosphorus (0-6")

Fertilizer Phosphate (P2O5) Recommended (lb/ac)

Soil Potassium (0-6")

Fertilizer Potash (K2O) Recommended (lb/ac)

Soil sulphate-Sulphur (0-24")

Fertilizer Sulphur (S) Recommended (lb/ac)

ppm lb/ac Rating Sb2 ppm lb/ac Rating Sb2 PPI3 lb/ac Rating N/A3

0 0 VL 40 1 0 VL 30 60 0 VL 20

5 VL 40 25 50 VL 30 60 5 VL 20

5 10 L 40 50 100 VL 15 30 10 VL 20

15 L 35 75 150 L 15 30 15 L 20

10 20 M 30 100 200 L 0 0 20 L 20

25 M 20 125 250 M 0 0 25 M 20

15 30 H 15 150 300 M 0 0 30 M 20

35 H 10 175 350 H 0 0 35 H 0

20 40 VH 10 200 400 VH 0 0 40 VH 0

20+ 40+ VH+ 10 200+ 400+ VH+ 0 0 40+ VH+ 0

Sb2 = Side Banded Adapted from the Manitoba Agriculture Food and Rural Initiatives.

PPI3= broadcast and pre-plant incorporated

N/A3= placement does not influence effectiveness of sulphate forms of sulphur fertilizer

Plant Tissue Analysis

Planttissueanalysisisanimportanttoolinassessingnutrientstatusofthegrowingcrop.FollowingareplanttissueanalysisinterpretivecriteriausedbytheformerManitobaAgricultureProvincialTestinglaboratory(Table5).Theselevelsshouldbeusedforthetoponetothreemostmatureleavesatthebudstage.However,ifadeficiencyisdetectedatthisstage,yieldpotentialhasalreadybeenaffected.Thissamplingmethodisbestusedasanauditingtooltodetermineifyourfertilityprogramissufficientfortheyieldpotential.Ifanutrientdeficiencyisobservedearlier,sampleplantsandsoilfromtheaffectedareaandcontrastresultswithplantandsoilsamplesfromanadjacent,normallookingarea.Thisisconsidereddiagnosticsamplingandcouldbeusedtocorrectsomein-seasondeficiencies.Consultwithyoursoilandplanttissuelaboratoryforguidelineswhensamplingatothergrowthstages.


Introduction|9

Table 5. Sunflower tissue analysis interpretation

CONTENT

Nutrient Low Marginal Sufficient High Excess

Nitrogen % N 1.4 1.5-1.9 2.0-3.4 3.5-3.9 4.0

Phosphorus %P 0.14 0.15-0.24 0.25-0.49 0.5-0.79 0.8

Potassium %K 0.9 1.0-1.4 1.5-2.9 3.0-4.9 5.0

Sulphur %S 0.14 0.15-0.19 0.2-0.39 0.4-0.99 1.0

Calcium %Ca 0.19 0.2-0.29 0.3-1.9 2.0-2.4 2.5

Magnesium %Mg 0.09 0.1-0.19 0.2-1.4 1.5-1.9 2.0

Zinc ppm ZN 11 12-14 15-69 70-149 150

Copper ppm (Cu) 2 3-5 6-24 25-74 75

Iron ppm (FE) 14 15-19 20-249 250-499 500

Manganese ppm (Mn) 9 10-14 15-99 100-249 350

Boron No provincial guidelines developed. Consult analytical companies

Special Fertility Considerations

Sunflowershavedeeptaprootsthatcanobtainwaterandnutrientsfivetosixfeet(1.5to1.8meters)deepinthesoil.Thesereservesofwaterandnutrientsareunavailabletomostotherannualcrops,makingsunfloweragoodrotationalcrop.Sunflowershavetheabilitytoscavengenitrogenthathasleachedbelowtherootingdepthofothercrops.

SEEDING Planting dates

SunflowerseedingshouldusuallybeginanytimeafterMay1andideallybecompletedbyJune1.Seedlingsarerelativelyfrosttolerantuptothefour-leafstage.ChooseearliermaturinghybridsoroiltypehybridsifplantingisdelayedintothefirstweekofJuneorforreplanting.Oiltypehybridsareshortermaturingthanconfectionvarieties.Plantingdatecanalsoaffectsusceptibilitytopests.Consultthefollowingchaptersastowhentoplanttoavoiddamagebythemostprevalentpestinyourarea.

Plant Populations and Row Spacing

Seedingrateforsunflowersdependsonsunflowertype.Oilseedvarietiesaregenerallyplantedathigherpopulationsthanconfectionaryvarieties.Oil-typesunflowerpopulationsrangefrom20,000to22,000plants/acre(0.6plants/ft2).


10|Introduction

Plant Populations and Row Spacing (Continued)

Confectiontypesunflowersshouldnotexceed18,000plants/acre(0.4plants/ft2)toensurelargeseedsize.Seedingratesforbothoilandconfection-typesunflowersshouldbeadjustedwhengerminationislow.Refertotables6and7forinformationonplantdensityandrowspacingaswellasseedsizeandweight.

Noyielddifferenceshavebeendetectedbetweensunflowersseededinrowsversussolidseededwhenadequateweedcontrolexists.Fieldswitharowspacinglessthan20inchesareconsideredtobesolidseeded.Recommendedrowspacingforsolidseedingis10to12inches(25.4to30.5centimeters)forbothconfectionandoil-typesunflowers.Plantpopulationsshouldremainthesameasstatedaboveregardlessofrowspacing.Equidistantplacementofseedswithintherowallowsformaximumutilizationofresources(e.g.water,nutrients,sunlight)andoftenresultsinconsistentheadsize.Sunflowerplantscompensatefordifferencesinplantpopulationsbyadjustingheadandseedsize.Asplantpopulationsincrease,headandseedsizedecreaseandviceversa.

Depth

Sunflowersneedtobeplacedinmoisturebutnotdeeperthanthreeinches(7.6cm).Theidealseedingdepthis1½to2inches(3.8to5cm)deep.Plantingequipmentshouldfirmthesoilovertheseedrowtomaintainamoistseedbedandensuregoodseedtosoilcontact.

Table 6. Seed spacing required for various populations, assuming 90 percent germination and 10 percent stand loss

ROW SPACING (inches)

Plants/acre 12 16 18 22 30 36

--------- Seed spacing within row (inches) ---------

14,000 30.2 22.6 20.2 16.5 12.1 10.1

16,000 26.5 19.8 17.6 14.4 10.6 8.8

17,000 24.9 18.6 16.6 13.6 10.0 8.3

18,000 23.5 17.6 15.7 12.8 9.4 7.8

19,000 22.3 16.7 14.9 12.2 8.9 7.4

20,000 21.2 15.9 14.1 11.5 8.5 7.1

21,000 20.2 15.1 13.4 11.0 8.1 6.7

22,000 19.2 14.4 12.8 10.5 7.7 6.4

23,000 18.4 13.8 12.3 10.0 7.4 6.1


Introduction|11

Table 7. Sunflower seed size and associated seed weight

OIL-TYPE SUNFLOWER CONFECTION SUNFLOWER

Seed Size Seeds/lb Seed Size Seeds/lb

No. 2 5,000 – 6,000 Medium 4,000 – 5,000

No. 3 6,000 – 7,000 Large 3,000 – 4,000

No. 4 7,000 – 9,000 Extra Large 2,000 – 3,000

FIELD SCOUTINGSunflowerareahosttoanumberofpests.Fieldsshouldbemonitoredregularlyforpotentialproblems,todeterminepestspeciespresentandifpopulationsareateconomicthresholdlevels.Fieldscoutinginvolveswalkingintothefieldandassessingtheoverallhealthofthecrop.Sunflowerpeststendnottobedistributedevenlythroughoutafield,sofieldsshouldbecheckedinseverallocations.Forexample,somepestsaremoreabundantnearthefieldedgesratherthaninconcentratedareaswithinthefield.Determiningtheextentofapestpopulationonthebasisofwhatisfoundinonlyoneortwosmallareasof afieldisimpossible.Samplingsitesshouldbeatleast75feetinfromthefieldmargin.Todeterminewhetheranentirefield,oraportionofthefield,requirestreatmentatleastfivesitesper40-acresshouldbemonitoredtocollectadequateinformationonthenatureandextentofapestinfestation.ThepaththroughthefieldshouldfollowtheZorXpatternasshowninFigure2.

Figure 2. The X and Z scouting patterns (NDSU)


TILLAGEManytillageregimesarepracticedinCanadaincludingconventional,strip,ridge,minimumandzero-tillage.Manyfactorsaretobeconsideredwhendecidingwhattillageregimetoutilize,includingsoiltype,climate,fertilizerregimeandrotation.Differenttillageregimesareassociatedwithdifferentimpactsoncropproductionandtheenvironment.Forexample,conventionaltillagecanbeutilizedtocontrolspecificcroppests,howeveritisalsoassociatedwitherosion.Minimum-orzero-tillagecanbeimplementedtomanageerosionandpreservethesoilprofile.Anunderstandingofthebenefitsanddrawbacksofeachtillageregimeisimportantwhendecidingwhichtoutilize.

HARVESTINGTiming

Sunflowersareusuallythelastcroptobeharvestedinthefallsincefallfrostshelpindryingdownthecrop.Theperiodbetweenmaturityandharvestshouldbekeptasshortaspossibletominimizelossesfrombirddamageandhead-rotdiseases.

Desiccation

Chemicaldesiccationisusedtoquickendry-downofsunflowerheads.Desiccationiseffectivebeforeakillingfrostinenhancingheaddry-downbutshouldnotbeappliedbeforethebackofthesunflowerheadturnsyellowandthebractsarebrownanddry.Thebracttipsturnbrownat40-50%seedmoisturewhichisstilltoohighfordesiccation.Propertimingiswhenmostofthebractshaveturnedbrown.Atthisstagetheplantisphysiologicallymatureandseedmoisturewillbe20to50percent.RefertothecurrentGuidetoCropProtectionfordetailsondesiccationproducts.

Combining

Sunflowerscanbecombinedwhentheseedmoistureisbelow20percent.Harvestingwhenseedmoistureisgreaterthan20percentcanresultinscuffingduringharvestingandshrinkageduringdrying.Itwouldbepreferabletocombineseedsat10to13percentmoisture.Sunflowerscaneasilyshatterifheadsareverydry,andthereforecombinespeedmustbeslowedaccordingly.Cylinderspeedsrangefrom300-500(rpm),withconcavesettingsquiteopen(oneinchinfrontand¾ inchinrear)tominimizeseedbreakageanddehulling.Usingtheslowestcylinderspeedswiththelargestopeningwillresultintheleastseeddamage.

Harvesting Attachments

Combinesthataresuitableforharvestingsmallgrainswillbeadequatetoharvestsunflowers.Aproperheaderattachmentisnecessarytoreduceshatteringlossesandharvestefficiency.

12|Introduction


Therearetwotypesofattachments:

� Thepanheaderwhichismountedontraditionalstraightcutheadersandissuitableforbothrowcropandsolidseeding.

� Theallcropheader,whichisonlysuitableforrowcropplanting.

Storage

Sunflowerseedissafetostoreatamoisturecontentof9.5percentorless.At10to12percentmoisturecontent,seedcanbestoredinbinswithaeration.Anymoisturecontentover12percentwillrequiredrying.Oil-typesunflowerscanbedriedwithtemperaturesof71-104°C(160-220°F)butconfectiontypesmayscorchorwrinklewiththesetemperatures.Sunflowerseedshouldbecooledbeforestorage,sinceevensunflowersat8.5percentmoisturecanspoilifstoredwhenwarm.

PEST MANAGEMENT INTEGRATED PEST MANAGEMENT IntegratedPestManagement(IPM)isasustainableapproachtomanagingpestsbycombiningbiological,cultural,physicalandchemicaltoolstominimizeeconomic,health,andenvironmentalrisks.Anumberoffactorsinfluencetheabundanceanddiversityofpestsfromyeartoyear.Controlmethodsvaryineffectiveness,butintegrationofdifferentpestmanagementtoolscanminimizepestnumbersandthecostofmanagementwithoutunnecessarycroplosses.IPMmaximizestheeffectivenessofchemicalpesticides,whileminimizingtheimpactonnon-targetorganismsandtheenvironment.

Scoutingforpotentialpests,monitoringfieldsandkeepingnotesofpestincidencesanddensitiesisrequiredtodetermineiflevelsareapproachingtheEconomicInjuryLevel(EIL)ortheEconomicThresholdLevel(ETL).Economiclossesarearesultofpestnumbersincreasingtowheretheycausecroplossesgreaterthanorequaltothecostofcontrollingthepest.TheEIListhenumberofpestsatwhichtacticsmustbeappliedtopreventanincreasingpestpopulationfromcausingeconomiclosses.TheETListhelevelofpeststhatwillcauseeconomicdamageandisoftenlowerthattheEIL.TheETLvarieswithcropprice,yieldpotential,cropdensity,costofcontrolandenvironmentalconditions.Pestsshouldbeidentifiedaccurately;controlmeasuresandeconomicinjurylevelsdifferbetweendifferentorganisms.Recognizingbeneficialorganismsisimportantastheyhelpreducenumbersofdamaginginsects,whichthenmaynotrequireadditionalcontrol.

Significantprogresswithinsunflowerpestmanagementstrategieshavebeenmade,andwillcontinuetobemadeintothefuture.Asnewcropmanagementstrategiesaredeveloped,itisimportanttoweighcropproductionbenefitsversusenvironmentalimpacts.

IntegratedPestManagement|13


INSECTS Thefollowingsectionsprovidecurrentinformationonmanagementofinsects,diseases,weedsandbirds.BelowisagrowingseasoncalendarthatshowsthemajorsunflowerpestproblemsandtimeofoccurrenceinthenorthernGreatPlainsproductionarea(Figure3).

Figure 3. A growing season calendar indicating time of occurrence of major sunflower pests. (J. Knodel, NDSU).

14|IntegratedPestManagement

APRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER

Crop Stages

Weed Control

Insects

Diseases

Birds

Emergence Vegetative Bud Flowering Mature

CutwormsPalestriped Flea Beetle Budworm Moth Budworm – 2nd Generation Longhorned Beetle (Dectes) Stem Weevil Sunflower Beetle Adults Larvae Adults Sunflower Maggot Adults Larvae Sunflower Moth Adults Larvae Banded Sunflower Moth Adults Larvae Seed Weevil Lygus Bug Head Clipping Weevil Sunflower Midge Grasshoppers

Blackbirds

Downy Mildew White Mold, Rust, Verticillum Wilt Apical Chlorosis Phoma Black Stem Head Rot Alternaria Leaf and Stem Spot Premature Ripening

Preplant and Preemergence Post Emergence Final Weed Survey

CONTROL TIPS Iftheriskofwirewormdamageishigh,seedscanbetreatedwithanapprovedinsecticideforprotectionofgerminatingseedsandseedlings.ConsultthecurrentGuidetoCropProtection.Norescuetreatmentsareavailableforcontrollingwirewormsafterplanting.

Figure 4. Wireworm larvae

4


SEEDLING AND ROOT FEEDERSWireworms

Wirewormlarvaefeedongerminatingseedsoryoungseedlings.Infestationsaremorelikelytodevelopwheregrasses,particularlyperennialgrasses,havebeengrowing.Stemsofyoungseedlingsmayemergeshreddedanddamagedplantsmaysoonwiltanddieresultinginthinstands.

Host Crops

Grasses,corn,carrots,potatoes,wheat,barley,pulsecrops,sunflowers,andmanyothercrops.

Biology

Wirewormlarvae(Figure4)areslender,smoothandhard-bodiedwire-likeworms varyingfrom1.5to2inches(38-50mm)inlengthwhenmature.Theyhave3pairsoflegsbehindthehead,areyellowishwhitetoacopperycolorandthelastabdominalsectionisflattenedandnotched.Itusuallytakes3to4yearsforwirewormstodevelopfromaneggtoanadultbeetle.Mostofthistimeisspentasa larva.

Boththewirewormadultsandlarvaoverwinterdeepinthesoil.Larvaemoveupanddowninthesoilprofileinresponsetotemperatureandmoisture.Aftersoiltemperatureswarmto50°F(10°C),larvaefeedwithin6inches(15cm)ofthesoilsurface.FromlateMaythroughJunethefemalebeetleslay200to1400eggsinloosesoilandunderlumpsofsoil.Whensoiltemperaturesbecometoohot(>80°F,27°C)ordry,larvaewillmovedeeperintothesoiltoseekmorefavorableconditions.Duetothis,wirewormsinflictmostoftheirdamageinearlyspringwhentheyarenearthesoilsurface.

Scouting Techniques

Soilsamplescanbecollectedandsievedinthespringtofindwirewormspresentinthefield.Soilshouldbesampledtoadepthof15cm(6inches)andrepeatedindifferentareasofthefieldtodeterminetheaveragenumberoflarvaepersquaremeter.Baitscanalsobeusedtoattractwirewormstoanareaformonitoring.Thepasthistoryofafieldisagoodindicator,especiallyifwirewormshavebeenaprobleminpreviousseasons.Croprotationmayimpactpopulationlevels.

Insects|15


Cutworms

Cutwormscanbeaseriousprobleminmanyfieldcrops.Therearemanydifferentspeciesinvolved,butthemostcommonaretheredbacked,darksidedanddingy cutworms.

Host Crops

Theredbackedcutwormfeedsinmostfieldcrops,vegetablesandhomegardenplants.Itisbestknownforfeedingoncereals,flax,canolaandmustard.

Biology

Cutwormlarvae(Figure5)havefoursetsofabdominalprolegsandcurlupwhendisturbed.Redbackedcutworms(Euxoa ochragaster)havetwobroadredorreddish-brownstripesthatextendstheentirelengthofthebody.Thetop-stripesaredividedbyadarklinewithwhiteinthecentre.Theheadisyellowish-brown.

Darksidedcutworm(Euxoa messoria)larvaearewhiteontheventralsidesandpalebrowndorsally.Theyhavenumerousindistinctstripes.Dingycutworm(Feltia jaculifera)larvaearedullbrown,withamottlecreamcolor.Thedorsalareaispalewithtracesofobliqueshading.

Cutwormmothsmaylayseveralhundredeggsinoronthesoil.Aftertheeggshatch,thelarvaefeedonthehostplants.Larvaenormallyhave6instarstages.Theymoultseveraltimes,eventuallyreachingaboutfivecentimeters(2inches)inlength.Thelarvaetunnelintothesoiltoformearthencellswheretheypupate andnewlyemergedmothsexitusingtheoldlarvaltunnels.Somespeciesoverwinteraseggs(e.g.theredbackedcutworm)oraslarvaeorpupae.StillothersdonotoverwinterinthePrairiesbutratherre-invadeannuallyfromtheU.S.,aidedbysoutherlywinds.Onegenerationofthisspeciesisproduced peryear.

Scouting Techniques

Cutwormsarenocturnal,feedingatnightandhidingduringthedaymakingthemhardtodetect.Oncethecrophasemerged,continuescoutingonaweeklybasisfrommid-Maytomid-June.Feedingbycutwormsresultsinnotched,wilted,deadandcut-offplants(weedsorcropseedlings).Plantsmaybemissingfromrowsandbarepatchesmayappearinfieldsasaresultofcutwormfeeding.Usingasmallgardentrowelandasoilsifter,cutwormscanoftenbefoundinthesoilaroundplantstheyhaverecentlydamaged.Cutwormsmaybe founddowntoabout5cm(2inches)belowthesoilsurface.Thesmall,worm-likelarvaecurluporattempttohideinthedebris.Pupaemayalsobecollectedinthisway.

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Figure 5. Different species of cutworm larvae.

CONTROL TIPS Bestresultsoccurifinsecticideapplicationsaremadeintheevening.Sometimesitismosteconomicaltojusttreatinfestedpatchesandnottheentirefieldastherearedifferencesinsusceptibilitytoinsecticidesbetweenspeciesofcutworms.ConsultthecurrenteditionofGuidetoCropProductionforregisteredinsecticides.

Youngcutwormlarvaemaybestarvedbeforespringseedingbyallowingvolunteergrowthtoreach3to5cm(1.2to2inches),cultivatingandthenseeding10to14dayslater.Manypredaceousinsects,parasitesandbirdspreyuponcutwormsandreducetheirpopulations.


Economic Thresholds

Treatmentiswarrantedwhencutwormdensitiesexceed1cutwormpersquarefoot(30cmx30cm)orifthereisa25to30%standreduction.

Sunflower Beetle

Feedingbyadultbeetlesandlarvamayresultinpoorseedset,seedfilling,reducedyieldsanddelayedmaturity.

Host Crops

Sunflowerbeetlesfeedonnativeandcultivatedsunflowers.

Biology

Adultsunflowerbeetlesthorax(areabehindthehead)isapalecream-coloratthetopwithareddish-brownpatchatthebase.Eachwing-coverhasthreedark-brownstripesthatextendthelengthoftheback.Thefourthstripeendsatthemiddleofthewinginasmalldotthatresemblesanexclamationpoint.Sunflowerbeetlelarvae(Figure7)areyellowishgreenwithabrownheadcapsuleandhumpbackedinappearance.Newlyhatchedlarvaeareabout1.5to1.75mm(1/16inch)longandwillgrowtoabout8to10mm(underhalfaninch)whenfullydeveloped.

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Figure 6. Adult – Sunflower beetle

Figure 7. Larva – Sunflower beetle7

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Biology (Continued)

Sunflowerbeetlesoverwinterasadultsinthesoil.Usually,theiremergencefromthesoilinthespringcoincideswiththetimethatsunflowerseedlingsbegintoappearinlateMay.Thebeetlesfeedthroughoutthedayontheemergingseedlings.Eggshatchaboutaweekaftertheyarelaidandtheyounglarvaefeedontheleavesatnight.Theyhideamongthebractsoftheflowerbudandintheaxilsoftheleavesduringtheday.Thelarvaefeedforabouttwoweeks,butbecauseofthelongegglayingperiod,larvaemaybepresentinthefieldforaboutsixweeks.Thematurelarvaedroptotheground,enterthesoil,andpupateinearthencells.Thepupalstagelastsabouttwoweeks.AdultsofthenewgenerationemergeandfeedforashortperiodinlateAugustandearlySeptember.Theyfeedontheuppermostleavesorbractsoftheplantbeforere-enteringthesoiltooverwinter.

Scouting Techniques

Noticeabledamageisoftenfirstseenonplantsnearthemarginsofsunflowerfields.Whenplantsareseedlings,scouttodeterminetheaveragenumberofadultbeetlesperplant.Forlargerplants,determinetheaveragenumberoflarvaeperplantandpercentdefoliationbysampling20plantsat5sitesalonganXpatternforatotalof100plants.

Economic Thresholds

Thethresholdis1to2adultbeetlesperseedlingatthetwotosixleafstageor10to15larvaeperplantduringthesummer.Severeleafdamagemayoccurtoplantsinthetwotosixleafstageswhenadultbeetlesarenumerous.Controlmaybenecessaryifdefoliationcausedbyeithertheadultsorthelarvaereaches25to30percent,especiallyifmoredefoliationisexpected.Ifthemajorityofthelarvaehavereachedmaturityatabout25percentdefoliation,controlshouldnotbenecessary.

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CONTROL TIPS Naturalcontrolsusuallykeepsunflowerbeetlepopulationsbelowdamaginglevels.Sunflowerbeetleeggsareeatenbythethirteenspottedladybeetleandtheconvergentladybeetle.Larvaeofthecommongreenlacewingconsumebotheggsandlarvae.Damselbugsandthetwospottedstinkbugmayalsopreyonlarvaeofsunflowerbeetles.Parasitoidsattacksunflowerbeetleeggs,larvae andadults.Insecticidesareavailabletocontrolsunflowerbeetle.ConsultthecurrenteditionoftheGuidetoCropProtectionforregisteredinsecticidesthatcontrolsunflowerbeetle.

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CONTROL TIPS Insecticideusehasnotbeenwarantedforcontrolofthistlecaterpillar.

Figure 8. Thistle caterpillar

Figure 9. Painted lady butterfly


Thistle Caterpillar

Thistlecaterpillar(Vanessa cardui)hasbeenanoccasionalpestofsunflowers.Localizeddamageofsunflowercropshasoccurredduringsporadicyearsofhighpopulations.

Host Crops

OnCanadathistle,larvae(Figure8)feedselectivelyonfoliage,leavingonlythestemandmidrib.

Biology

Adults,commonlyknownaspaintedladybutterflies(Figure9),arriveonthePrairiesduringearlyJune,dependingonspeedandpatternofmigration,fromoverwinteringsitesintropicalandsubtropicalareas.Thereisnoevidencethattheycansurviveourcoldwinters.ThisbutterflylayseggsonCanadathistleandabroadrangeofhostplants.Larvaefeedontheleavesproducingloosewebbing.Thelarvaeareupto30mm(1.25inches)longanddarkpurpletoblackincolor.Theyhavelongspinesoneachsegmentoftheabdomen.

Scouting Techniques

Ifpopulationsseemheavywhilescouting,sampleabout100scatteredplants,notingthepercentdefoliationoneach.Dividethetotalpercentdefoliationbythenumberofplantssampledtoobtainanestimateofpercentdefoliationforthe field.

Economic Threshold

Thethresholdis25percentdefoliationprovidedthatmostofthelarvaearestillunder3centimeters(11/4inches)long.Ifthemajorityoflarvaearefullygrown,mostofthefeedingdamagewillhavealreadyoccurred.

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Figure 10. Adult Sunflower bud moth

Figure 11. Sunflower but moth larvae

Figure 12. Entrance hole of larva

Figure 13. Larva feeding results in deformations of the sunflower head, often a hole is formed.

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INSECTS IN THE STEM Sunflower Bud Moth

Highpopulationsofthispesthavebeenreportedinthepast.Despitehighpopulations,thesunflowerbudmothmaynotcausehighlevelsofeconomicloss.

Biology

Sunflowerbudmoths(Suleima helianthana)haveawingspreadofabout16to18millimeters(0.63 inches).Eachgray-brownforewinghastwodarktransversebands(Figure 10).Onebandextendsacrossthemiddleofthewing,andthesecondbandislocatednearthewingtip.Thelarva(Figure11)haveadarkheadcapsulewithasmooth,cream-coloredbody.

InManitoba,twogenerationsofsunflowerbudmothareproducedperyear.AdultsemergefromoverwinteringpupaeduringthelastweekofMaytomid-June.Afewdaysafteradultemergence,eggsaredepositedontheterminalsofimmaturesunflowersoronthereceptacleofmaturesunflowers.Eggsalsoaredepositedinleafaxils.Thehatchedlarvaebegintunnelingintothesunflowerplant.Theinitialinfestationinmid-Juneischaracterizedbyanentranceholesurroundedbyblackfrass(insectexcrement)(Figure12).Maturelarvaepupatewithinthesunflowerplant.Pupaemovetotheopeningoftheentranceholesformedinthestemorheadtissuesothatadultscanemergeeasily.ThesecondgenerationadultsappearinJulyandAugust.Infestationsbythesecondgenerationlarvaearenoteconomicallyimportant.

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Inearlyplantedsunflower,mostoftheinfestationsoccurinthestalks,whereasinlateplantedsunflower,mostinfestationsoccurinthepithareasofthehead.Theonlytimeyieldlossisnoticeableiswhenlarvaeburrowintounopenedbuds,preventingproperheaddevelopment.Thelarvaenormallydonotfeedondevelopingseeds,butconfinefeedingactivitiestothefleshlypartofthehead.Despiteminimaleconomiclosses,thelarvacausemalformationsinboththeheadandstalk(Figure13).

Scouting Techniques

Afieldmonitoringschemeforthisinsecthasnotbeenestablishedsinceitisnotofeconomicsignificance.

Economic Threshold – Nonehasbeendetermined.

CONTROL TIPS Insecticideusehasnotbeenwarrantedforcontrolofsunflowerbudmoth.


Sunflower Stem Weevil

Therearetwomainstemweevilsspecies,theSpottedSunflowerStemWeevilandtheBlackStemWeevil.

Biology

TheSpottedStemWeevil(Cylindrocopturus adspersus)adultsareabout4to5millimeters(3/16inch)longandgrayishbrownwithvaryingshapedwhitespotsonthewingcoversandbetweentheheadandabdomen.Thesnout,eyesandantennaeareblack.Thelarvaeare5to6mm(1/4inch)longatmaturityandcreamywhitewithasmall,brownheadcapsule.ThelarvaewillnormallybeinacurledorC-shapepositionwhenfoundinsunflowerstalktissue.ThespottedstemweeviladultsemergeinmidtolateJuneandfeedontheepidermaltissueofthesunflowerfoliageandstem.Thisfeedingdoesnotaffectplantvigor.Matingoccurssoonafteremergenceofadults.Justpriortoegglaying,femalesdescendtothelowerportionoftheplanttodepositeggsindividuallyintheepidermaltissueofthestem.Eggsareverysmall(0.51mmlongby0.33mmwide).UponhatchinginearlyJuly,thefirstinstar(larvalgrowthstage)larvaefeedonsub-epidermalandvasculartissue.Feedingisconcentratedinthepithtissueasthelarvaedeveloptothirdandforthinstars.

BythelastweekinAugust,thelarvaehavedescendedwhilefeedingtojustabovethesoilsurface.Arudimentarychamberisconstructedinthestem,andtheweevilsoverwinterinthischamberasfifthinstarlarvae.PupationoftheoverwinteringlarvaoccursthefollowingyearinearlyJune.Thereisonegenerationperyear.

TheBlackStemWeevil(Apion occidentale)adults(Figure14)areblackandonly2.5mm(0.1inches)longfromthetipofthesnouttothetipoftheabdomen.Thesnoutisverynarrowandprotrudesforwardfromthehead,whichissmallinrelationtotheratherlargebody.Thelarvaeareverysimilarinappearancetothespottedstemweevilexcepttheyareonly2.5to3mm(0.1to0.12inches)longatmaturityandyellowishincolor.

Theblackstemweeviloverwintersasadultsinsoil,plantresidue,sodandweedclusters.Uponemergence,theadultsfeedonvolunteersunflowersintheearlyseedlingstage.Adultfeedingoncultivatedsunflowerbeginsatthetwo-tofour-leafstage.Femalesdepositeggsundertheepidermisofthestem.Larvaeemergingfromtheseeggstunnelinthepithareaofthestem,pupateandemergeasadultsinearlyAugust.

LittleornoadultactivityisobservedforabouttwoweeksinlateJulyandearlyAugust.ApionadultsemerginginAugustalsofeedontheleavesandstemsoftheplant,butastheplantmaturesandtheleavesbegintodie,theadultsmoveunderthebractsofthesunflowerheadswheretheycanbeobservedfeedinguntiltheplantsareharvested.

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ThesetwospeciesarehighlysuspectedinvectoringPhomablackstem,adiseaseinsunflowerfields.Theonlyspeciesofstemweevillarvathathasbeenfoundtocauseseriousstalkbreakageisthespottedstemweevil.Whenlarvalinfestationsofthisspeciesreach25to30ormoreperstalk,considerableweakeningofstemtissuecanresult,especiallywhentheselarvaebegintocreatetheiroverwinteringcellsinthebaseofthesunflowerstalks.Breakageismostlikelytooccurwhenplantsareunderdroughtstressand/orduringperiodsofhighwind.Thebreakagetypicallyoccursatorslightlyabovethesoilsurfaceincontrasttobreakageattributedtostalkdisease,whichnormallyoccursfartherupthestalks.

Scouting Techniques

LookforstemweevilswhenscoutingsunflowerfieldsinlateJuneandveryearlyJulyusingtheXpatternandexamining5plantsperstopforatotalof25plantsatthe8to14leafstage.Samplingsitesshouldbe75to100feetinfromthefieldmargins.Theaveragenumberofweevilsperplantcanthenbecalculated.

Whensurveyingforstemweevils,moveslowlytoavoidhavingtheadultstemweevilsdroptothesoiland‘playdead’.Adultfeedingbybothstemweevilspeciesisconsideredtocauseinsignificantmechanicalinjury.

Economic Thresholds

Theeconomicthresholdforthespottedsunflowerstemweevilisoneadultperthreeplants.

Figure 14. Adult Apion black sunflower stem weevil (NDSU).

14CONTROL TIPS NoinsecticidesarecurrentlyregisteredforcontrolofsunflowerstemweevilsinManitoba.DelayedplantingofsunfloweruntillateMayorearlyJunehasbeeneffectiveinreducingdensitiesoflarvaeinthestem.Falltillagepracticeswhicheitherburyorbreakupsunflowerstalkswillhelpincreasewintermortalityofstemweevillarvae.Naturalenemiesofthestemweevilincludethreespeciesoflarvalparasitoidsandoneeggparasitoid.Thesewaspshaveaccountedforapproximately30percentmortalityofthestemweevilsinthepast.


Sunflower Maggots

Therearethreemainspeciesthathavelarvalfeedingstagesthatcancauseseedsterilityorstalkbreakageunderhighpopulations.Damageisusuallynegligible.

Biology

Theadultformsofallthreesunflowermaggots(flies)havewingswithadistinctbrownoryellowish-brownpattern.Whileallthreeflyspeciesaresimilarinappearance,theydohavedistinguishingdifferences.

Sunflower receptacle maggot (Gymnocarena diffusa)

Thisspeciesisthelargestofthethreewithabodyabout10mm(0.4inches)longandawingspanofapproximately19mm(0.75inches).Theeyesofthisspeciesarebrightgreenandthewingshaveayellowish-brownandsomewhatmottledappearance.Sunflowerreceptaclemaggotlarvaeattainalengthofnearly8mm(0.31inches)atmaturity.Thelarvae(Figure15)taperfromthefronttotherearandareyellowish-whiteincolor.

AdultsofthesunflowerreceptaclemaggotemergeinlateJunetoearlyJulyaftersunflowerbudsreach5to10cm(2to4inches)indiameter.Eggsarelaidonthebractsofthedevelopingsunflowerheads.Egglayingoccursfrommid-JulythroughAugust.Thehatchedlarvaetunnelintothespongytissueofthereceptacle.Damagetotheheadisnegligible.After30days,thematurelarvaecutasmallemergenceholeontheundersideofthereceptacleanddropintothesoiltopupate.Overwinteringpupaearefoundabout19cm(7.5inches)deepinthesoilbyAugustorearlySeptember.Somelarvaewillpupateinthesunflowerhead.ThereisonlyonegenerationperyearinManitoba.

Sunflower maggot (Strauzia longipennis)

Adults(Figure16)ofthisspecieshaveawingspreadofabout13mm(0.5inches)andabody6mm(0.25inches)long.ThewingsbearbroaddarkbandsthatformafairlydistinctF-shapedmarknearthetips.Thelarvae(Figure15)ofsunflowermaggotarecreamywhite,headlessandlegless,asaretheothertwospecies.Theytaperslightlyatbothendsandattainalengthofabout7mm(0.28inches)atmaturity.

Sunflowermaggotshaveonegenerationperyear.Thisinsectoverwintersaslarvaeinplantdebrisinthesoil.PupationandadultemergencearecompletedinearlyJune.Femaleslayeggsinstemtissueofyoungsunflower,andlarvaefeedinthepithtissueformuchofthegrowingseason.

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Sunflower seed maggot (Neotephritis finalis)

Thissunflowermaggotisthesmallestofthethreespecieswiththeadulthavingabodylengthofabout6mm(0.25inches)andawingspanofapproximately7mm(0.28inches).Thewingshaveabrownlace-likeappearance.N. finalis larvaeattainalengthof4.5mm(0.19inches)atmaturity.

Unliketheothertwospeciesofsunflowermaggots,sunflowerseedmaggotscompletetwogenerationsperyear.Thefirstgenerationpupatesinthehead;thesecondgenerationoverwintersinthesoilaspupae.

Scouting Techniques

Scoutingtechniqueshavenotbeendevelopedforsunflowermaggotsbecausetheycausenegligibledamage.

Economic Threshold – Noneestablished.

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CONTROL TIPS Insecticideshavenotbeenwarrantedforcontrolofthispest.

Figure 15. Sunflower maggot larva

Figure 16. Adult sunflower maggot

Figure 17. Sunflower maggot larval feeding causes deformations of the head.


INSECTS ON THE HEADSSunflower Midge

Midgelarvaecanaffectthegrowthofsunflowerheads.Heavily-damagedheadsbecomegnarledandcuppedinwardly,producingfewseeds.

Host Crops

Sunflowers

Biology

Thetiny,tan-colored,adultsunflowermidge(Contarinia schulzi)areonlyabout2mm(1/8inch)longwithawingspanofabout4mm(0.07inch).Thewingsaretransparentandvoidofmarkingsexceptfortheveins.Thefirstpeakoffirst-generationadultemergenceoccursinearly-tomid-July.Asecondpeakoccursabout7to10dayslater.Theadultsprefertolaytheireggsonsunflowerbudswithadiametergreaterthan1inch.Eggsarelaidindividuallyoringroupsindepressionsbetweenthebractsofthesunflowerbud.Themidgelarvaaretiny,beingonly3 mm(1/8inch)longwhenfull-grownandcreamtoyellowishorange.Thenewlyemergedlarvaemovetothebaseofdevelopingseedsorbracts.Presenceofthelarvaeisfrequentlydeterminedbynecroticareasatthebaseof,orbetween,bracts(Figure18).Theyusetheirraspingmouthpartstofeedontheplanttissuesintheselocations.Maturelarvaedropfromtheheadandburrowintothesoil.Ifconditionsarefavorable,theypupateandemergethesameseason.Otherwise,theyremaininthesoilandoverwinteraslarvaeincocoonsor,insomecases,aspupae.Thesecondgenerationadultslaytheireggsamongtheseeds.Usually,thelarvaepupateinthespring.TheadultsstarttoemergeinlateJune.Theadultmidgeonlylivefortwotothreedaysandaredifficulttofindinthefield.

Scouting Techniques

Althoughdamagemaybesevere,itisusuallysporadicandlocalized.Damagetoheadsisusuallyrestrictedtofieldmarginsbut,insevereinfestations,damageispresentthroughoutthefield.Whenmonitoringsunflowerheads,lookformidgelarvaeintheflowerhead,scarredbracts,andtwistedorgnarledflowers.Thelarvaemaybefoundatthebaseofthebractsorfeedinginthefloweratthebaseoftheflorets.A10xmagnifierhelpsinlocatingthetinylarvae.

Economic Threshold

Nothresholdhasbeenestablishedforthispestineitheroiltypeorconfection sunflowers.

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CONTROL TIPS Delayedplanting(untillateMay)mayavoidthefirstmajoremergenceoftheoverwinteringpopulation.However,laterinfestationscanstillbesevere.

Somecommercialhybridsaretoleranttosunflowermidge.Consultyourlocalseeddealerforinformationonthemostresistantvarieties.

Insecticidesdonotworkwellagainstthispest.Theyprovideinconsistentandinadequatecontroloftheadultsandlarvae.Becausethelarvaecrawlintothebudsoonafterhatching,theyareprotectedfromfoliarapplications.Insecticidescancontrolthesunflowermidgeonlyiftheyareappliedtothefoliagejustbeforetheadultsemerge.However,becausethisemergencecannotbeaccuratelypredicted,insecticideapplicationsareineffective.

Figure 18. Larvae feeding causes brown necrotic spots at the base of the bracts.

Figure 19. Severe midge damage causes over growth of the sunflower head.

Insects|27


Sunflower Seed Weevils

Larvaefeedonkernels,causingreducedseedweightandoilcontent.Oftenthekernelsareonlypartiallyfedupon,makingitdifficulttoseparatehealthyfromweevil-damagedseed.Thiscausesdowngradingofconfectionarysunflowerseed.

Host Crops

Sunflowers

Biology

TherearetwospeciesofSeedWeevilsthatcancausedamageinsunflowersinCanada;theredsunflowerseedweevil(Smicronyx fulvus)andthegraysunflowerseedweevil(Smicronyx sordidus).TheredsunflowerseedweevilisthemostcommonofthetwospeciesonthePrairies.Theadults(Figure20)are2.5to3.06mm(1/10to1/8inch),longandarecoveredwithreddish-orange,ovalscales.TheadultsappearduringlateJuneonvolunteersunflowersandfeedonthebractswheretheyformpinpointholes.Asthebuddevelopsandopens,adultsmovetotheinflorescenceandfeedonpollenproducedbythediskflowers.Femaleslaytheireggsinsidetheseedcoatofdevelopingseeds.Populationsarehighestonplantsat50%flowering.Theegglayingpatternfollowsseedfillingwhichprogressesfromtheoutsidetothecenterofthehead.Usually,aninfestedseedcontainsasinglelarva.Thelarvaearesmall,creamcolored,leglessandC-shaped.InlateAugust,thematurelarvaechewanexitholeintheseed,droptothegrounddirectlybeneaththesunflowerhead,andoverwinterinthesoil.

Thegraysunflowerseedweevilisnotascommonandisslightlylarger(3to3.5 mmor1/8inchlong)thantheredseedweevillarvae.Seedsinfestedbythelarvaeenlarge,protrudingabovethesurroundingseeds,andlackakernel.Thedamagecausedbyasinglelarvaofthisspeciesexceedsthatoftheredseedweevilbecauseofthelossoftheentirekernel.However,itusuallydoesnotcauseeconomicdamagetosunflowersusedforoilbecauseofitslowpopulationlevelandlowreproductiverate.

May June July August September

Larvae overwinter in soil

Larvae pupate, new adults feed on volunteer sunflowers

Females lay eggs in developing seeds, eggs hatch

Larval feeding, larvae move into soil

Larvae overwinter in soil

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CONTROL TIPS


Scouting Techniques

Beginscoutingforseedweevilsassoonastheyellowraypetalsappear.Continuecountsuntiltheeconomicthresholdlevelhasbeenreachedormostplantshavereached70%pollenshedatwhichtimeveryfewseedsaresuitableforegglaying.

Whensampling,followanXorZpatterninthefield.Initiatecountsmorethan100feetintothefieldascountstakenalongthefieldmarginwillleadtoabnormallyhighweevilcountsthatwillnotberepresentativeofthefield.Countthenumberofweevilson5plantsateachsiteforatotalof25plants.BrushthefaceoftheheadsvigorouslytobringtheweevilstothesurfaceorspraymosquitorepellentcontainingDEETonthehead.Thiswillforcetheweevilstomoveoutoftheirhidingspots.Careshouldbetakentonotconfuseotherinsectswhichmaybepresentonsunflowerheads,suchasminutepiratebugs(Figure21)forseedweevils.

Economic Thresholds

Inoilseedsunflowers,thethresholdis10to12weevilsperplant.Inconfectionsunflowersthethresholdis1to2weevilsperplant.

Figure 20. Adult Red Sunflower Seed Weevil

Figure 21. Sunflower seed weevils on top and the much smaller minute pirate bug nymphs below.

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Earlyplantinghelpsreduceseeddamage.Whenplantedearly,thesunflowersarecompletedanthesis(flowering)beforepeakweevilpopulationsandarenolongersusceptibletoegglaying.

Insecticides,sometimesincombinationwithtrapcropping,remainsthemajormanagementtool.Determinetheaveragesunflowerplantgrowthstagebeforeapplyinganinsecticide.TheweevildoesnotbegintolayeggsonsunflowerheadsbeforeR5.4(theouter40%offloretshaveopened).Iftreatmentisnecessary,insecticidesshouldbeappliedbeforethreeoutoftenplantsreach40%bloom.


Banded Sunflower Moth

Larvaefeedonsunflowerfloretsandseeds.

Host Crops

Commercialsunflowers.Severalspeciesofwildsunflowersarealsoknownhostsofbandedsunflowermoth.

Biology

Thebandedsunflowermoth(Cochylis hospes)isasmall,straw-coloredmothabout7mm(0.3inch)long(Figure22)withabrowntriangularareainthemiddleportionofthefrontwings.Newlyhatchedlarvaeareoff-whitewithadark-brownheadcapsuleandabout1.5mm(0.06inch)long.Asthelarvaegrow,thereisagradualcolorchangetolightpinkoryellow,thentoreddishorpurplishandfinallytogreenatmaturity(Figure23).Full-grownlarvaeareabout10mm(0.4inch)long.

Theadultmothsstartemergingfromthesoilinmid-Julyandarepresentthroughtomid-August.Mothsflyfromlastyear’ssunflowerfieldstothecurrentyear’ssunflowerfields.Adultmothsrestinvegetationalongfieldmarginsduringthedayandmoveintothefieldtolayeggsattwilight.Theylayeggsonthebractsofsunflowerheads.Eggshatchin5to8days.Larvaecanbepresentinsunflowerheadsfromaboutmid-Julytomid-September.Maturelarvaedroptothegroundandspincocoonsinthesoilwherewinterispassed.PupationtakesplaceinlateJuneorearlyJulythefollowingyear.

Newlyhatchedlarvaemovefromthebractstothefloretsofthesunflowerhead,wheretheyenteropenfloretstofeed.Ifeggshatchpriortotheopeningoftheflorets,larvaewillfeedonbracttissuebeforemovingtotheflorets.Larvaecontinuetofeedinthefloretsuntilthethirdinstar,reducingthetotalnumberofmatureseedsproduced.Duringlaterstagesofdevelopment,thelarvaetunnelthroughdevelopingseeds,usuallyenteringatthetopandleavingafterthecontentsareeaten.Eachlarvamaydestroy6to7matureseedsinadditiontothefloretseatenbytheearlierinstarlarvae.Sincetheseedkernelisentirelyconsumedbythelarva,theseedwillnormallypassthroughthecombine.

Thegreatestdamagebybandedsunflowermothlarvaehasbeenshowntooccurattheedgeofthefield.

Scouting Techniques

Fieldsshouldbemonitoredwhenplantsareinthelatebud(R-4)toearlybloomstage(R-5.1)ofdevelopment.

Monitorforadultmothsinearlyeveningorearlymorningwhenthemothsaremostactive.Samplingsitesshouldbeatleast75to100feet(23to30m)fromthefieldmargin.Countmothson20plantsfrom5differentsitesforatotalof100plants.

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CONTROL TIPS Iftreatmentiswarranted,itshouldbeappliedattheR5.1sunflowerplantgrowthstage.Insecticidesshouldbeappliedearlyinthemorningorlateinthedaytominimizetheadverseeffectonbeesandotherpollinators.Parasiticwaspsattackboththeeggsandlarvaeandgeneral

predatorsinthesunflowerfieldalsoconsumebothlarvaeandeggs.Minutepiratebugsfeedontheeggsandyounglarvae.Groundbeetlescandestroyabout40%ofoverwinteringlarvaeandpupae.Atleast4differentspeciesofparasitesattackthelarvaeofthebandedsunflowermoth.

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Figure 22. Banded sunflower moth adults are characterized by the dark band along the middle of the back.

Figure 23. Larva go through 5 instars and feed on the developing kernel within the seed.

Figure 24. Banded sunflower moth larva create a webbing on the face of sunflower heads.


Samplingstrategiesbasedonscoutingforadultmothsduringdaylighthoursandforeggshavealsobeendeveloped.

Economic Threshold

Ifmonitoringintheearlyeveningorearlymorning,onebandedsunflowermothpertwoplantsisareasonableeconomicthreshold.

NOTE:TheArthur’ssunflowermoth(Cochylis arthuri)isverysimilartothebandedsunflowermoth.TheArthur’ssunflowermothlarvaealsofedondevelopingseedsinthesunflowerheadcausingsimilardamagetothatofthebandedsunflowermoth.Theadultsalsohavedarkbandingacrossthewings,althoughtheycanbedistinguishedfrombandedsunflowermoth.Younglarvaearecreamcolored,mid-instarlarvaearelighttodarkpink,andlast-(fifth-)instarlarvaearelighttodarkgreen.

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Lygus Bug

Feedingbylygusbugsondevelopingseedscancausekernelbrownspot,smallbrowntoblackspotsonthebluntordistalendofsunflowerseeds.

Host Crops

Lygusbugshavebeenrecordedonover385cropandweedspecies.

Biology

Adultlygusbugs(Figure25)areabout5mm(0.2inch)longand2.5mm(0.1 inch)wide.Theyvaryincolorfrompalegreentoreddish-brownandhaveadistincttriangleor“V”markonthewings.Firststagenymphsareverysmall,winglessandbrightgreen.Nymphs(Figure26)maylooksimilartoaphidsbutaremuchmoremobile.

Lygusbugsfeedonplantsbyinjectingplanttissuewithdigestiveenzymes,andthenextractingnutrientswiththeirneedle-likemouthparts.Lygusbugfeedingondevelopingsunflowerseedscancausescarringontheseeds,knownaskernelbrownspot.Whilebrownspotisnotknowntoaffectyield,thisqualityissuecanbesignificantinconfectionsunflowersbecauseprocessorsareonlyallowed0.5%damageinthefinishedproduct.Lygusbugfeedingcanalsoresultinabittertastetotheseeds.Whilebrownspotisvisibleondehulledkernels,thereisusuallynosignontheexteriorofthehullthatthekernelhasbrownspot.

Lygusbugsaremobileandcanbefoundonmanycrops.Lygusbugsprobablymovetosunflowersfromalfalfa,canolaorotherhostcropswhenthosecropshaveeitherbeenharvestedorsenesced.

Scouting Techniques

Scoutforadultsornymphsonthesunflowerheadsorfoliage.

Economic Thresholds

Lygusbugsarecapableofdamaging30to35seedsperheadperadult.Withtheindustrystandardallowingforamaximumof0.5%kernelbrownspot,theeconomicthresholdforlygusbugsonsunflowersislikelyabout1lygusbugper9heads.

Inresearchtrials,damagetosunflowerheadswasapproximatelytwiceasseverewheninfestationsoccurredatlatebudandearlybloomcomparedtostageswhenheadshadcompletedflowering.Thus,lygusbugmanagementshouldbeinitiatedpriortooratthebeginningoffloweringifadultdensitiesapproachtheeconomicthreshold.Fieldsshouldbemonitoredforlygusbugsuntilfloweringiscompletedtoreduceincidenceofkernelbrownspotdamageto confectionsunflowers.

25 26


CONTROL TIPS

InsecticideapplicationismostbeneficialwhenappliedduringearlyfloweringattheR5.1stage.AsecondapplicationmaybewarrantedifLygusbugpopulationsarehighinneighboringfields,andpopulationsareexpectedtomigratetothesunflowerfield.ConsultthecurrentGuidetoCropProtectionforregisteredinsecticides.

Figure 25. Adult lygus bugs are characterized by a triangle across the wings.

Figure 26. Lygus bug nymphs resemble the adults but lack wings.

Insects|33

30 31 32

2927 28


BENEFICIAL INSECTS

34|Insects

Minute Pirate Bug

Bothnymphsandadultsfeedonavarietyofsunflowerpestsincludingaphidsandtheeggsandlarvaeofbandedsunflowermoth.

Green Lacewing

Adultsfeedonaphidhoneydew,plantpollenandplantnectar.

Green Lacewing Larvae

Predatortoavarietyofsunflowerpestsincludingaphids,sunflowerbeetleeggsandlarvae,andbandedsunflowermotheggsandlarvae.

Lady Beetles

Consumesunflowerbeetleeggs,aphids,andbandedsunflowermotheggsandlarvae.

Lady Beetles Larvae Damsel Bugs

Preyonsunflowerbeetlelarvae,andbandedsunflowermotheggsandlarvae.

3736

33 3534


Insects|35

Two-Spotted Stink Bug

Preyonsunflowerbeetlelarvae.

Parasitic Wasps

Attackboththeeggsandyounglarvae ofbandedsunflowermoth,sunflowerseedweevilsandsunflowerstemweevils.

Ground Beetles (Carabid Beetles)

Candestroy40percentofoverwinteringlarvaeandpupaeofsunflowerbeetles.

Hover Fly

Increasescropyieldbyenhancingpollination.Feedson aphids.

Honey Bee

Increaseyieldinsunflowerbyenhancingpollination.


Pollination

Unlikenativesunflowers,currenthybridshavebeenselectedforandpossesshighlevelsofself-compatibility.Althoughself-compatiblesunflowerhybridsusuallyout-produceself-incompatiblecultivars,modernhybridscontinuetobenefitfrominsectpollination.Studieshaveshownthatinmostsunflowerhybridsseedset,yieldandoilquantityisincreasedwhenpollinators(suchasbees)arepresent.

Toachievemaximumyieldsandquality,oftentheuseofinsecticideisrequiredtoprotectthecropfrominsectcompetitors.Unfortunately,manyofthemajorinsectpestsofsunflowerattackthecropduringfloweringandinsecticideapplicationsharmthepollinatingbees.Belowaresomekeystrategiesthatcanhelpprotectthepollinators.

Key strategies:

� Scoutfieldsandapplyinsecticideonlywhenneeded.� ApplyInsecticideintheevening-Honeybeesareforagingwhenthesunis

upandduringthewarmerpartsofthedayandreturntothehiveatnight.Whenthebeesreturntothefieldthenextday,theeffectonthebeeswillbesignificantlyreduced.

� Lessharmfultobeesdoesnotnecessarilymeanlessharmfultopests–Thisisduetotherepellenteffectonbeesfromtheresidueofsomeinsecticides.Selectinsecticidesthatprovideeffectivecontrolofthetargetedpestswhileminimizingimpactonbees.

� Communicatewithbeekeepers–Contactingthebeekeeperaboutaninsecticideapplication,theinsecticidechosen,andthestepstakentoreduceharmtopollinators,helpsthebeekeepertodecideifadditionalmeasuresshouldbetakentominimizebeedamage.

36|Insects

38

39


DISEASESEARLY SEASON DISEASESDowny Mildew

Downymildewiscapableofkillingorstuntingplants,reducingstandsandcausingsevereyieldlossesduringwetyears.

Host Crops

Sunflower

Biology

Downymildewiscausedbyasoil-borne,wind-borneandseed-bornefungiPlasmopara halstedii,whichcansurviveforupto10yearsinsoil.Undercool,water-saturatedsoilconditions,thesporesgerminateuponcontactwithsunflowerroots,enter,andspreadthroughouttheentireplant.Thisissystemicinfection.Systemicinfectionoccursonlywhentherootsarelessthan2incheslongwhentheycontactthefungi.Sunflowerplantssurvivingtheinitialinfectionwillproducewhitesporesontheundersideofcholoroticareasonleaves.Thewhitesporesareair-borne,anduponlandingonsunflowerleavesmaycausesecondaryinfections.Secondaryinfectionsaremostcommonwhensunflowerleavesremainwetforprolongedperiodsoftime.Plantsaresusceptibletosecondaryinfectionsforamuchlongerperiodoftimeversussystemicinfectionsviarootinfection.Asinfectedplantsrotandaretilledintothesoil,thefungusformstherestingstagewhichwillgerminateduringfavorableconditionsinsubsequentyears.

Figure 38. Seedling Sunflower with downy mildew.

Figure 39. Downy Mildew causes stunting and heads to face straight upwards.

Diseases|37


Symptoms

Symptomscanvaryconsiderablydependingonamountofinoculum,theageandhostorganattackedandenvironmentalfactors.Symptomscanbebroadlyclassifiedasthosecausedbysystemicorlocalizedinfections.Rootinfectionofseedlingsoryoungplantsresultsinsystemicinfection.Severelyinfectedplantsmaydiebeforeorshortlyafteremergenceorintheseedlingstage.Typicalsystemicsymptoms(Figure38)inseedlingsincludedwarfing,yellowingoftheleavesandtheappearanceofwhite,cottonymassesonthelowerandsometimesupperleafsurfaceduringperiodsofhighhumidity.Whenseedlingsareinfectedseveralweeksafteremergence,orafungicideseedtreatmentinhibitsratherthanpreventsinfection,theplantsstartshowingsymptomsatthefour-,six-,oreight-leafstage;thisistermed‘delayedsystemicinfection’.Theseplantsmayormaynotdeveloptypicaldownymildewleafsymptoms,butaretypicallystuntedwiththickened,clublikeroots.Theheadsofthefewplantsreachingmaturityfacestraightupwardsandseldomproduceviableseed(Figure39).Airbornedownymildewsporescancauselocalizedsmall,angularfoliarlesionswiththewhitefungalgrowthontheundersideoftheleaf.Theseinfectionsgenerallyhaveminimalimpactonyield.

Yieldlossesmaybesubstantial.Ifinfectedplantsaredispersedrandomlythroughoutthefield,yieldlossesprobablywillnotbeobservedunlessinfectionexceeds15percent.Neighboringplantscancompensateforseverelyinfectedplantsbygrowinglargerheads.Whenthediseaseisinalocalizedarea,suchasalowspotinafieldandallplantsareinfected,yieldlosscanbesubstantial.

Scouting Techniques

Infectedplantscanmostoftenbefoundaloneorinstandingwater.

38|Diseases

CONTROL TIPS

Resistantvarietiesareavailable;however,duetothedevelopmentofnewraces,resistancemaynotbeasufficientmanagementtoolinallfields.Fungicideseedtreatmentscanbeaneffectivemanagementtoolfordownymildew,butaswithgeneticresistance,thepathogenhasdevelopedresistancetometalaxylandmefanoxam,twoofthemostcommonlyusedfungicides.Otherseedtreatmentoptionsareavailableandmorewillbelabeledinthefuture.RefertothecurrentissueoftheGuidetoCropProtectionforupdatedinformationonproductsandratesforapplication.Othermanagementproceduresaretocontrolweedhostswhichincludewildandvolunteersunflowerstohelpreduceinoculum.


FOLIAR DISEASESRust

Earlyinfectionofsusceptiblevarietiescandecreaseheadsize,seedsize,oilcontentandyield.Confectionhybridsaremoresusceptiblethanoil-seedtypes.

Hosts

Wildsunflowerandcultivatedsunflower

Biology

SunflowerrustiscausedbyPuccinia helianthi.Infectioncanoccuratanytimeduringthegrowingseason,dependingontheinoculumsourceandenvironmentalconditions.Conditionsfavorableforinfectionarefreewaterontheleaves,eitherfromrainfallordew,andwarmtemperatures.Aminimumoftwohoursofwetleavesissufficientforrustinfection;sixtoeighthoursofleafwetnessresultsinthemaximumamountofinfection.Sunflowerrustsporesoverwinteronthedebrisfrominfectedsunflowerleavesandstemsofpreviouscrops.Inthespringsporesgerminatetoinfectvolunteerseedlings,wildsunflowerornewyoungplantsinnearbyfields.Underfavorableconditions,sporeproductionandinfectioncanoccurcontinuouslywithinayear.The‘repeatingstage’isthemostdamaging,asmultiplewavesofsporesarespreadbywindtootherfieldsasconditionsallow.Asthecropripens,thesporesformtheoverwinteringstagewhichcanthenre-infectfollowingsunflowercrops.

Symptoms

Thefirstsignsofrustusuallyappearwhensunflowersareatorpastbloomasenvironmentalconditionswithinthecropcanopyaremorefavorableforinfection.Theaecialstage(Figure41)ofrustappearslatespringtosummerasclustersoforangecups.Themostcommonstageofrust(uredinia)(Figure 42)isoftenobservedwithintwoweeksoftheaecia.Thesepustulesaresmall(0.1to1mm),cinnamon-brown,canberubbedofeasilyandoccuronboththeupperandundersidesofleaves.Asthediseaseprogresses,urediniamaybefoundontheupperleaves,stemandbractsofthesunflowerplant.Inresponsetotemperature,theurediniaconverttotelia(blackspotsontheuppersurfaceofleaves)attheendoftheseasonwhichdonotruboffandaretheoverwinteringstructures.

Economic Threshold

Rustseverityontheupperfourleavesis3percentorgreater.

Diseases|39

0.5% Leaf Area Infected 1% Leaf Area Infected 2% Leaf Area Infected 5% Leaf Area Infected

Figure 40. Leaf area infected by rust.

42

CONTROL TIPS

Themosteffectivewaytoavoidlossfromrustisbyplantingrust-resistanthybrids.Mostoilseedandconfectionaryhybridshavegoodtoexcellentresistancetomostracesofrust.Rotationtoothercropsisalsoausefultooltominimizeinfections,assunflowerrustonlyinfectssunflowers.Ifpossible,avoidplantingnexttoafieldthathadsunflowerslastyear;managewildsunflowersorvolunteersunflowersastheyarehostsforthedisease.Earlyseedingandshortseasonhybridscanalsohelpminimizediseaseseverity.Anyculturalpracticewhichfostersadensecanopy,suchashighplantstandsandhighnitrogenfertilization,whichtrapsdew,increaseschancesofasevererustinfectionandshouldbeavoidedifrisksarehigh.Foliarfungicidesareregisteredforrust.ConsultthecurrenteditionofGuidetoCropProtectionfor products.

Figure 41. Aecia cups on the underside of sunflower leaf.

Figure 42. Rust uredinia develop on the under-and upper-leaf surfaces.

41


40|Diseases


Alternaria Leaf and Stem Spot

Alternarialeafspotisaubiquitousdiseaseonsenescingleavesandgenerallyoflittleconcern.Underwarmandhumidconditions,itcanhoweverbecomeaseriousdefoliatingandyieldreducingdisease.

Host Crops

Sunflower,safflowerandcocklebur

Biology

Alternariafungioverwinterondiseasedstalksandmaybeseed-borneatlowlevels.SeedlingblightscausedbyAlternariamaydevelopwhensunflowerplantsemergeinrainyweatherinAlternaria-infestedsoil.Alternariasporesarespreadbywindandsplashingwater.Thefungirequirefreewaterfor4hoursforinfectiontooccur.Leafsymptomsaremostfrequentlyobservedafterfloweringasthedensecanopyisconducivetoinfection.Onceestablished,thediseasecandevelopquicklyunderfavorableconditions.InwesternCanada,climateisnottypicallyconduciveforAlternariaepidemicsandgenerallyonlythelowersenescingleavesareaffected.

Symptoms

Darkbrownirregularspotswithdarkbrowntopurplebordersandagraycenterdeveloponleaves(Figure43).Thespotsonyoungplantsmayhaveayellowhalo.Leaflesionsmaycoalesce,causingleavestowither.Stemlesionsbeginasdarkflecksthenenlargetoformlong,narrowlesions.Thestemlesionsoftenjointoformlargeblackenedareaswhichmayresultinstembreakage.Thelesionsarelocatedrandomlyalongthestemandnotassociatedwithapetiole.

43

CONTROL TIPS

Croprotationandburyinginfestedcropresidueto hastendecompositionhelpsminimizeAlternaria infection.

Figure 43. Alternaria leaf lesions close up.

Diseases|41


Septoria Leaf Spot

Septoriaiswidelydistributedonsunflowersbutusuallycauseslittledamage.Insevereinstancesitcancausedefoliationofthelowerleaves.

Host Crops

CultivatedandWildSunflower

Biology

SeptoriaiscausedbythefungiSeptoria helianthi.Thefungisurviveoninfectedcropresidueandcanalsobeseed-borne.Thediseasecanappearanytimeduringthegrowingseasonwithinitiationfavoredbymoderatelyhightemperaturesandabundantrainfall.

Symptoms

Septoriadevelopsfirstonthelowerleavesandspreadsupwardsthroughthecanopy.Thelesions(upto15mmindiameter)beginaswater-soakedareaswhicharegreasygreeninappearance.Thespotsbecomeangulartodiamondshaped,withtancentersandbrownmargins.Youngspotsareoftensurroundedbyanarrowhalothatgraduallymergeswiththesurroundinggreentissue(Figure44).Maturespotscontainsmallblackspecksorfruitingbodies.ThisisthebestwaytodistinguishAlternariafromSeptoria.Thelesionsmaycoalesceinlaterstagesandtheleafmaywitheranddie.

42|Diseases

44 CONTROL TIPS

Croprotation,incorporationofsunflowerresidueanduseofcleanseedarethebestmanagementpracticestomanageSeptoria.

Figure 44. Septoria lesions contain small black fruit bodies.

STALK AND ROOT-INFECTING DISEASESSclerotinia Wilt and Basal Rot

Infectedplantsdierapidly,andiftheplantdiespriortoseedmaturityitresultsinyieldloss,lowertestweight,andloweroilcontent.

Host Crops

Sclerotiniahasaverywidehostrangeofover360species,whichincludessunflowers,canola,mustard,drybeans,fieldpeas,lentilsandpotatoes.

45 46


CONTROL TIPS

Managementofsclerotiniaisdifficultbecauseofthewidehostrange,butrotationtocerealsandcornisthemosteffectivetominimizesclerotiniainthesoil.Sunflowerhybridswithsomelevelsofresistanceareavailable.TheuseofamycoparasiteswhichfeeduponotherfungihasshowntoattackSclerotinia.OnecommerciallyavailableisConiothryium minitans(Contans).Thismycoparasitecankillsclerotiainseveralmonthsratherthanyears.

Figure 45. Sclerotinia wilt.

Figure 46. Sclerotinia Basal rot lesion.

Biology

SclerotiniaoverwintersasSclerotinia sclerotioruminthesoiloronplantdebris.Sclerotiaareirregularlyshapedstructureswhichrangeinsizeandshapefromsphericaland1/8inchindiametertoY-shapedandupto1inchinlength.Thesclerotiabodiescansurviveinthesoilfor5ormoreyears.Assunflowerrootsgrownearsclerotiniainthesoil,thesclerotiaarestimulatedtogerminateproducingmyceliumwhichinfectsthelateralroots.Sclerotiaforminthedecayedstempithandontherootsastheplantdies.Thesclerotiaarereturnedtothesoilduringtillageoperationsandserveassourcesofinoculumforthenextsusceptiblecrop.

Soilmoistureandtemperatureduringthegrowingseasonarenotcriticalfactorsaffectingtherateofincidenceofsclerotiniawilt.

Symptoms

Wilt(Figure45)canappearatanytimebetweenemergenceandmaturity,butismoreprevalentaroundflowering.Suddenwiltoftheplantoccurswheninfectedrootscannotuptakeadequatewatertomeetthedemandsoftheplant.Examinationofthestem-rootareawillrevealatan-brown,watersoakedlesionatthesoilsurface(Figure46).Thestalksandrootsmaybecomecoveredwithwhitemyceliaandhardsclerotiabodiesdevelopunderverywetsoilconditions.

Diseases|43

47


Sclerotinia Mid-Stalk Rot

Mid-stalkrotisthediseaseleastoftencausedbySclerotinia.Lodgingcancausecompleteyieldlossonaperplantbasis.

Biology

Underwetsoilconditions,thesclerotiainthesoilcangerminatetoformsmallmushroomscalledapotheciathatproduceair-bornespores.Thesporescanoriginateinthesunflowerfieldorcanbeblowninfromadjacentfields.Sporescanmovebyrainsplash,variousinsectcarriersandupto1kmbyair.Thesporesrequirefreewaterandsenescingplanttissuetogerminateandinfectplants.Mid-stalkinfectionmayresultfromleafinfectionorinfectionattheleafaxil.

Symptoms

Infectioncanoccuranytimefromseedlingtomaturitydependingonthepresenceofinfectingsporesandfavorableenvironmentalconditions.Mid-stalkrotbeginswithinfectionoftheleaf,andthefungusprogressesinternallythroughthepetioleuntilitreachesthestem.Theleaflesionsarenotuniqueenoughtoidentifythefungus,butthestemlesionsareidenticaltothatformedbyrootinfection;tancoloredandwater-soaked(Figure47).Thesclerotiacandevelopwithinthestemorontheexteriorofthestem.Leavesabovethelesionwilt,andthestalkeventuallydisintegratesbecomingshreddedasonlyvascularcomponentsofthestemremain(Figure48).

CONTROL TIPS

ThecommentsmadeaboutSclerotiniawiltalsoapplytomid-stalkrotmanagement.Culturalpracticestoavoidhighplantdensitiesbyreducingpopulationsandhighnitrogenfertilizationhelplowertheincidenceofinfection.Shalloworzero-tillagepracticesmayaidinfasterdeteriorationassclerotiaareleftonthegroundsurfaceandsubjecttoincreasedenvironmentaldeterioration.Resistancegeneshavebeenthemosteffectiveapproach,andbreedingforhighertolerancecontinues.

Figure 47. Sclerotinia mid-stalk rot lesion

Figure 48. Sclerotia bodies develop within the stem tissue or on the surface of the stem.

48

44|Diseases

49


Phoma Black Stem

PhomaisthemostwidespreadstalkdiseaseinthenorthernGreatPlains,but yieldlossesareconsideredminimal.

Host Crops

Cultivatedsunflower

Biology

Thefungus(Phoma macdonaldii )overwintersininfecteddebris.Phomainfectionoccursthroughoutthegrowingseason;however,itisnotusuallynoticeduntilthestemlesionsbecomeobviouslaterinthesummer.Leavescanbeinfectedbywindcarriedspores,rainsplashedsporesorsporestransmittedbyinsects.Stemweevilsaresuspectedintransmittingthefungiinternallyandexternally.Adultweevilsfeedingontheleavescauseleaflesionswhereascontaminatedlarvaespreadthefungusastheytunnelthroughoutthestem.LeaflesionsarenotdistinctiveandcanbeconfusedforAlternaria.Theleafinfectionsprogressdownthepetioletothestalk.Underfavorableconditions,theleafwilts,thepetioleturnsuniformlyblack,andthestemlesionsexpand.

Symptoms

Large,jetblacklesionsdeveloponthestem(Figure49),sometimesreachingabout4to5cminlength.Thelesionsareuniformlyblackandshinywithdefiniteborders.Smallcircularfruitingbodiesofthefungusareproducedonthesurfaceofthestembuttheserequireahandlenstosee.Thefungusmayalsoproducelesionsonthebackofthehead,ontheleaves,andatthebaseofthestalk.Stemlesionsdonotresultinpithdamageorlodgingandaregenerallyregardedassuperficiallesions.IfstemweevillarvatunnelingspreadsPhomasporeswithinthepith,extensivepithdegenerationcanoccur.

CONTROL TIPS

CulturalpracticestominimizePhomaincludesafouryearrotationtominimizetheinoculumloadinthesoil,delayedplantingandavoidinghighplantpopulationsandhighnitrogenfertilization.Controlofstemweevilscanhelpreducetransmissionofthefungusbutinsecticideapplicationisrarelyeconomicallyjustified.Somehybridsaremoretolerantthanothers,butnoneareimmunetothe disease.

Figure 49. Phoma black stem lesion

Diseases|45


Phomopsis Stem Canker

InrecentyearsPhomopsishasbecomeaveryprevalentdisease.Yieldlossesresultfromsmallerheads,lighterseedandlodgingduetoweakenedstems.

Hosts

Sunflower

Biology

Thefungi(Phomopsis helianthii)overwinteroninfectedplantdebrisandsporesarerainsplashedorwindblownontoleaves.Theinfectioninitiatesatleafmarginsoflowerleaves,developingintoabrownnecroticareaborderedbyachloroticmargin.Theinfectionspreadsdownthroughtheveinstothepetioleandfinallytothestem.ThesymptomsaresimilartothoseofVerticilliumleafmottle;however,withVerticilliumveinsremaingreen.Stemlesionsusuallydonotappearuntilflowering.Thediseaseismostsevereunderconditionsofprolongedhightemperaturesandhighrainfall.

Symptoms

Firstsymptomsinitiateonlowertomiddleleavesafterfloweringasnecroticspotswithachloroticborderonleafmargins.Thestemlesionsbeginasasmallbrownsunkenspotbutenlargesrapidlybecomingalargetantolightbrownlesionorcankercenteredonaleafpetiole.LesionsaremuchlargerthanPhomablackstem,sometimesreaching6inchesandbrownratherthanblack.Blackfruitingbodies(pycnia)formoninfectedtissue.Phomopsiscausesextensivepithdegradationandthestalkcanusuallybecrushedundermoderatethumbpressure.PhomopsisinfectedplantsaremorepronetolodgingthanPhomainfectedplants.

50CONTROL TIPS

Thoroughincorporationofthesunflowerstalksintothesoiltoburyresidueandcroprotationcanreducediseaseincidenceandseverity.CropresidueleftonthesoilsurfacefostersdevelopmentofPhomopsis.HybridsresistanttoPhomopsis,developedusingparentallinesfromEuropewherethediseaseisparticularlysevere,arecommerciallyavailable.

Figure 50. Phomopsis Stem Canker

46|Diseases

51


Verticillium Leaf Mottle

Verticilliumcansignificantlyreducesunfloweryieldespeciallyonlightersoils.Qualitymayalsobeaffectedthroughdecreasedoilcontentandseedsize.

Host Crops

Variousplantspeciescanbeinfectedincludingsunflowers,potatoes,alfalfaandsweetclover

Biology

Thefungus(Verticillium dahliae)isseed-andsoil-borne.Itsurvivesasverysmall,black,restingbodies(microsclerotia)indiseasedsunflowerdebrisandbroadleavedweeds,persistingfor5to10years.Themicrosclerotiagerminateinresponsetorootexudates.Theroottipsofsunflowerplantsareinvadedand,eventually,allpartsoftheplantbecomeinfected.Thefungusproducestoxinswhicharetranslocatedthroughouttheplantcausingthechloroticandnecroticareasbetweentheveins.Whentheplantdies,thefungusproducesblackfungalbodiesthatreturntothesoilwiththeplantdebris.

Symptoms

Symptomsusuallyarenotobserveduntilflowering,butmayappearatthesix-leafstageundersevereconditions.Initialsymptomsbeginastinychloroticflecksthatincreaseinsizewithtimedevelopingintoextensiveinter-veinalyellowing(Figure51).Symptomsbeginonthelowerleavesandprogressslowlyuptheplantandmayeventuallyinfectallleaves.Affectedleavesquicklybecomedry.Thevascularsystemmaybediscoloredbrown,apparentasaringaroundthepithincrosssection.Inseverelyinfectedplants,thepithisblackenedwithalayeroftinyblackfruitingbodies.

CONTROL TIPS

Mostoil-seedhybridscontainresistancetoVerticilliumwhereasconfectionhybridsaregenerallymoresusceptible.However,anewstrainhasrecentlybeenidentifiedinCanadaandtheU.S.whichisabletoovercomethesourceofresistanceinthesevarieties.Thediseaseismoresevereonlighterlandwithahistoryofsunflowercroppingthanonheavy,claysoil.Rotationisimportantonlightersoilwithahistoryofsunflowercroppingtoreduceinoculumloadinthe soil.

Figure 51. Verticillium Leaf Mottle

Diseases|47


HEAD ROT AND DISEASES OF MATURE PLANTSSclerotinia Head Rot

Head-rotisconsideredthemostimportantdiseaseaffectingsunflowerproduction,causingyieldandqualityloss.

Hosts

Sunflower,canola,mustard,drybeans,fieldpeas,lentils,potatoes

Biology

Sclerotiniahead-rot(Figure52)isquitevariable,usuallyoccurringlateintheseasonandinfluencedprimarilybytheamountofrainfallfromfloweringthroughtoharvesting.Aswithsclerotiniamidstalkrot,head-rotiscausedbyair-bornesporesproducedbyapothecia(smallmushrooms)eitherwithinthefieldorblownfromaneighboringfield.Thesporesrequirefreewaterandafoodbasesuchasdeadorsenescingplanttissuetogerminateandinfect.Ascosporescolonizethedeadfloretsandpollenonthefaceofthehead.Afterinfectionittakesseveralweeksuntiltheappearanceofbrownlesionsonthebackofthehead.

Symptoms

Thefirstsymptomsofheadrotusuallyaretheappearanceofwater-soakedspotsorbleachedareasonthefleshybackofthehead.Thefunguscandecaytheentirehead,withtheseedlayerfallingawaycompletely,leavingonlyableached,shreddedvascularsysteminterspersedwithlargesclerotia.Thebleached,skeletonizedheadsresemblestrawbroomsandareveryobviousinthefieldevenfromadistance.

Yieldlossfromheadrotonanindividualplantcanrangefromminimaltototallossiftheheaddisintegratesanddropsalltheseedtothegroundpriortoharvest.Intactbutdiseasedheadswillhavelightandfewerseeds,withloweroilcontentandwillshatterduringharvest.

52

48|Diseases

CONTROL TIPS

Sunflowerhybridsexhibitvariablerangeofsusceptibilitytoheadrot,butnohybridsarecommerciallyavailablewithadequateresistance.Fungicidesmayhelpreducetheincidenceofheadrot,withapplicationsmadepreventivelysinceseveralweekslapsefrominfectiontosymptomdevelopment.ConsultthecurrenteditionoftheGuidetoCropProtectionforproductinformation.

Figure 52. Sclerotinia Head Rot


Rhizopus Head Rot

RhizopusisaverywidespreaddiseaseinthecentralGreatPlains.Affectedheadswillhavealightertestweight,loweroilcontentandreducedseedyields.

Host Crops

ManyhostsforRhizopusincludingsunflower,beetsandtobacco

Biology

Susceptibilityoftheheadincreasesfromthebudstageuptothefullbloomandripeningstages.Sporesaredisseminatedbywind,rainandinsects.Rhizopusenterstheheadthroughwoundscausedbyhail,birds,insectsandhasbeenassociatedwithsunflowermidgedamage.Rapiddiseasedevelopmentoccursinwarm,humidweather.Oncetheheadisfullycolonizedandalltissuekilled,theheaddriesupandbecomes‘mummified’.

Symptoms

Initialsymptomsaresimilartootherheadrotdiseases;brown,sunken,watersoakedlesionsonthebackofthehead.Asthelesionsenlarge,theinterioroftheheadbecomesmushy(Figure53).Theinterioroftheheadbecomesfilledbymyceliuminterspersedwithblackfruitingbodiesresemblingpeppergrains.Oncetheheaddriesupitischaracterizedbyadarkbrown,pepperyappearanceoftissuesinthereceptacleandbecomesveryhard.

53

CONTROL TIPS

ControllingheadinsectsisthemostefficientmethodtominimizeincidencesofRhizopusheadrot.Geneticresistancehasbeenidentified,butseverityofthediseasehasnotwarrantedintensiveresearch.RotationdoesnothelpreducetheincidenceofRhizopusduetothenumberofRhizopusspecies.NofungicidesareregisteredforcontrolofRhizopusheadrot.

Figure 53. Rhizopus Head Rot

Diseases|49


54

BLACKBIRDSSunflowerseedsareparticularlyvulnerabletopredationbyblackbirdsduetothehighnutritionalvalue,easyaccessibility,andheadsservingasaperchduringfeeding.Blackbirdnestsarebuiltindensevegetation,mostoftencattails.Afternesting,blackbirdsformlargeflocksandbeginfeedingingrainfieldsandforthisreason,extensivefeedingdamageoftenoccursnearcattailmarches.Feedingbeginssoonafterpetaldropandmostofthedamageoccursduringthefollowingthreeweeks.Peakconcentrationsofblackbirdsoccurinmid-September,coincidingwiththecropreachingphysiologicalmaturity.

Control

Acombinationofculturalpracticesmaybeusefultoreducetheriskofblackbirdpredationonsunflowers.Suchpracticesinclude:

• Plantatthesametimeasneighbors–blackbirdsareattractedtoearly maturingsunflowers.

• Donotplantsunflowersnearcattailmarshesorwoodlots-cattailchoked sloughsserveastheroostingsitesforblackbirds.

• Delayedcultivationofcropstubbleincreasesalternatefeedingareasto preventpredationonneighboringsunflowerfields.

• Desiccatetoadvanceharvestandreducetheexposuretimetoblackbirds.

• Decoycroppingtoattractblackbirdsawayfromhighvalueconfectionaryand oilseedvarieties.

• Employscaremethodstofrightenblackbirdsaway.Cannonsareavailable fromyourlocalConservationoffice.

• Cutcattailswhereviableusingamoweroracattailharvester.

Figure 54. Cattails serve as the roosting sites for blackbirds.

50|Blackbirds

55CONTROL TIPS

Noin-cropherbicidesareavailableforcontrolofcockleburinsunflower.Cockleburplantsareshorterandaretypicallynotharvestedwiththesunflowerseed.Useofanall-cropheaderincreasesthepotentialforcockleburseedstobecollectedasitcutsclosertotheground.Croprotationswithsmallgrainsandcultivationhelpmanagecockleburproblems.

Figure 55. Mature cocklebur plant


WEEDSWeedscompetewithsunflowersforresources,limitingcropgrowthandreducingyield.Yieldlossescausedbyweedcompetitionisafactorofweedspecies,density,relativetimeofemergencetothecropandenvironmentalconditions.Weedspeciesdifferincompetitiveability;somecausinghigheryieldlossesonaperplantbasis.

Sunflowersareagoodcompetitoroncethecropisestablished.Weedcompetitionduringtheearlystagesofgrowthhasthelargestimpactonyield,thustheCriticalPeriodofWeedControlinsunflowersisV-EtoV-4.

Thefollowingweedsectionscontainsinformationonspecificweedspeciesthataredifficulttocontrolinsunflower.

Cocklebur

Cockleburhastheabilitytoreducecropyieldsandqualityconsiderably.Itisanannualplantthatusuallygrowsinrangelands,alongroadsides,andinwasteareas.Cockleburissaidtobeoneofthebiggestforeignmaterialproblemsforconfectionarysunflowerprocessors.

Quick ID

Seedling –Longandnarrowcotyledons.Thestembelowthecotyledonsispurplishgreen.Firsttrueleavesaretriangularwithtoothedmargins.Iftheplantispulledup,theremainsoftheburcanbeusedtoconfirmseedlingidentification.

Juvenile–Cockleburhasanerect,ridged,rough-hairystemwithpurplishspots.Leaveshavethreemainveinsandareheart-shapedortriangular.Leavesandstemsareroughtothetouch.

Mature–Femaleandmaleflowersareonthesameplant,butareseparate.Themaleflowersaresphericalandnon-spiny.Thefemaleflowerisgreenandspiny.Ifcrushedtheplantgivesoffadistinctiveodor.

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52|Weeds

CONTROL TIPS

Biennialwormwoodhasnaturaltolerancetomanysoil-appliedandpost-emergencebroadleafherbicides.Wherepossible,pre-emergentfollowedbypost-emergentherbicideapplicationsarethemosteffectivestrategytocontrolbiennialwormwood.Sinceitcangerminateseasonlong,asoilappliedherbicidewithprolongedresidualactivityisneededtoprovideoptimalmanagement.

Sulfentrazonehasshowntohaveupto80%controlofbiennialwormwoodinNDSUtrials,butnodatatosupportthathasyetbeenestablishedinCanada.

Post-emergentherbicidesmustbeappliedtoseedlingslessthan8cmtall.Noin-cropherbicidesareregisteredforcontrolofbiennialwormwoodinsunflower.Forthisreason,croprotationandplanninginpreviouscropsisimportanttomanagetheweed.RefertotheGuidetoCropProtectionforproductsthatcancontrolbiennialwormwood.

Biennial Wormwood

Anative,prolific,small-seededweedforwhichbothannualandbiennialtypescoexist.Traditionally,biennialwormwoodhasbeenclassifiedasanon-croplandweed,andthereforereceivedlittleattentionasamajorarable-landweed.Plantstypicallygrow3to7feettallwithawoodystemaveraging1to2inches(3to 5 cm)indiameter.

Seedlingemergencecanoccurduringtheentiregrowingseasonunderfavorableconditions.Theplantgrowsslowlyafteremergence,remainingasarosetteuntilmidsummer,afterwhichgrowthbecomesrapid.Biennialwormwoodisoftenconfusedforcommonragweed.

Quick ID

Seedling–Cotyledonsareovaloroblongandverysmall(2to3mm).Firsttwoleavesareopposite,ovaltoelongatedhaving2smallteethontheleafmargin.

Juvenile –Formsabasalrosette,short-stalked,pinnatelydividedandre-dividedleavesthatarecoarselytoothed.

Mature –Erect,hairlessplant,withaslenderstemandlittletonobranchinggrowing10to175cmtall.Leavesappeartoformawhorlaroundthestem.Green,inconspicuousclustersofflowersdeveloponshortbranchesintheaxilsofsmallleavestowardsthetopofthestem.Whentheupperleaves,stemandflowerheadsarecrushed,theygiveoffanodorresemblingacombinationofsageandcarrot.

Biennial Wormwood VS. Common Ragweed

Biennialwormwoodhavehairlessleaveswithsharpedges,whereascommonragweedleavesaresmooth,hairyandhaveroundedges.

Figure 56. Biennial wormwood seedling

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Canada Thistle

Isaveryaggressivecreepingperennialthathasthepotentialtocausesignificantyieldloss.Canadathistlespreadsprimarilybyadeep,horizontal,creepingrootsystemformingdensepatches.Itthrivesinawiderangeofsoiltypes,growingbestindisturbedareasandovergrazedpasture.Asingleplantcanproduceover6mofrhizomeperyear.ItistheseundergroundrootsthatmakecontrolofCanadathistledifficult.Canadathistlehasseparatemaleandfemaleplants,whereonlythefemaleplantsproduceseed.Eachplantmayproduceover40,000seeds,whichcanremainviableinthesoilfor21years.

Quick ID

Seedling-Oblongtobroadlyovalcotyledons.Shootsthatemergefromundergroundrootbudslackcotyledons.Firsttrueleavesareovatewithsharpspinesalongmargins(Figure57).

Juvenile-Irregularlylobedleaveswithspinesonlyonthemargins.Plantsvaryintheextentoflobing,lengthofspinesonmarginsandthepresenceorabsenceofhairontheundersidesoftheleaves.Uppersurfaceisshiny.

Mature –Headsformattheendofstemsinclustersmadeofnumerouspinkishpurplediscflowers.Bractsareflattenedandendinshort,weakprickles.

Stemsarehollow,erectandsmooth;spinesmaybepresentnearthebaseoftheplant.


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CONTROL TIPS

MostofthebiomassofCanadathistleplantsisbelowground;thereforekillingtherootsistheonlyeffectivecontrolmethod.Anintegratedmanagementplanisrequiredtoreduceinfestations.Rhizomesareunaffectedbycultivationastheygrowbelowthenormaltillagedepths.Rhizomeshigherinthesoilprofilethatarebrokenbytillagewillproducesmallrootpiecesthatrapidlydevelopintonewplants.Repeatedmowingoftheinfestationthroughoutthegrowingseasonoverseveralyearswilldepletethefoodenergystoredintherootsystem.AvarietyofherbicidesareavailableforcontrollingCanadathistle,butresidualherbicidesaremoreeffective.Fallapplicationsmaximizetranslocationofthechemicalintotherootssincetheplantisputtingreservesintotherootsystemtosurvivethewinter.Springapplicationsjustcausere-sproutingoftheplants.Mosteffectivecontrolisthroughacombinationofspring-summermowing,followedbyafallherbicideapplication.

Figure 57. Canada thistle seedling

Figure 58. Juvenile Canada thistle

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54|Weeds

Kochia

Kochiaisanannualplant,originallyintroducedasanornamentalgardenplant.Sincethen,kochiahasbecomeamajorweedprobleminmanyareasofCanadacausingseverereductionsinyield.

Quick ID

Seedling–Cotyledonsareshortandnarrow,dull-greenontheuppersurfaceandbrightpinkontheunderside.Thefirstleaveshavemanysofthairs.Plantsformabasalrosettewhennotincompetitionwithothervegetation.

Juvenile–Hasanerect,purple-stripedstemthatisheavilybranched.Leavesretainthegreyish-greenappearanceandarehairy.

Mature–Leavesbecomemuchsmallertowardsthebranchtipsresultinginapyramid-shapedplant.Flowersaregreen,lackpetals,andareinconspicuousinleafaxils.Thewholeplantturnsbrightredinthefall.Whentheplantdries,thestembreaksoffatgroundlevelandactsasatumbleweed,scatteringseedsalongitspath.

CONTROL TIPS

Kochiaseedsremainviableinthesoilforapproximatelytwoyears.Forthisreason,preventingseedproductionforafewyearswillnearlyeradicatepopulations.Toadequatelycontrolkochia,anintegratedapproachisrequired.Falloworshorttermperennialforageproductionpreventsseedproduction.Seedlingsarecontrolledbylate-springcultivation.Sulfentrazone(Authority),apre-seedherbicide,isregisteredtocontrolkochia.Mowheavypatchesofkochiainsalineareastopreventseedproduction.Whensprayingseedlings,itisimportanttomaintainwatervolumesintheupperrecommendedrangestoachievesufficientcoverageandpenetratehairsontheleafsurface.Itisimprotanttorotateherbicidegroupsaskochiacanquicklydevelopherbicidetolerance.

Figure 60. Kochia seedlings

Figure 61. Kochia seedlings have densely haired leaves.

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Prairie Sunflower

Wildsunflowergrowstoaboutthesameheightascultivatedsunflower,competingforsunlight,spaceandmoisture.Itisahosttopestsofcultivatedsunflower,reducingyieldandquality.

Quick ID

Seedlings –Oblongcotyledonsandoppositelyarrangedfirstleaves.Oftenfoundonsandiersoils.

Juvenile–Leavesarelanceolatetoovateinshapewithawavymargin,whereasannualsunflowershavedistinctlytoothedmargins.Prairiesunflowerstemsarecoveredwithshorthairs,flattenedtothesurface.Thisiscontrastingtoannualsunflowerswhicharebristlytothetouch.

Mature–Theheadsofprairiesunfloweraresmallerthanannualsunflower.Thecentraldiskflowersarepurplishbrownandflattened.

62CONTROL TIPS

Pre-plantburndownisnecessaryusinganyofthelabeledproducts.SoloorOdysseysprayedinCLEARFIELDhybridsonlyandExpressinExpressSunhybridsonly,hasshowntoprovidecontrolofPrairieSunflower.Applicationoftheseherbicidesinnon-toleranthybridswillcauseextensivedamage.IftherearemanywildsunflowersgrowinginCLEARFIELDorExpressSunsunflowercrops,controlofthewildspeciesisessentialtopreventcross-pollinationwhichcouldcausethewildsunflowertodeveloptolerancetotheseherbicides,diminishingtheeffectivenessofthesetechnologies.ContactyourlocalseeddealertofindoutmoreabouttheCropStewardshipProgram.

Figure 62. Wild sunflower

Figure 63. Wild sunflower leaves have a wavy margin.

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63

CONTROL TIPS

Betweenrowcultivationorhoodedsprayerherbicideapplicationcanbeusedforcontrolin-crop.Pre-emergentherbicideapplicationsincludingGlyphosateadditionsoffergoodcontrol.Severalpre-seedherbicidesareregisteredandachievefairtogoodcontrolofwildbuckwheat.In-cropherbicidessuchasAssertareratedfairtogood.Bestcontrolisachievedwhenplantsare3inchesorsmaller.ConsultthecurrentGuidetoCropProtectionforupdatedinformationonregisteredherbicidesandapplicationinformation.

Figure 64. Wild buckwheat has arrow shaped leaves.

Figure 65. The cotyledons of wild buckwheat are angled at 120 degrees.

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56|Weeds

Wild-Buckwheat

AnannualintroducedfromEuropeincontaminatedseed,thistwiningnaturedplantmakesfieldworkdifficult.Althoughnotascompetitiveinsunflowercomparedtoothercropslikewheat,asignificantseedbankcanbeproducedinsunflowercreatingproblemsinfutureyears.

Quick ID

Seedlings–Linearcotyledonsattachedat120degreestooneanother.Thestembelowthecotyledonsisoftenreddishpurple.Thetrueleavesarearrowshapedwithpointytipsandpointedbasallobes.Apaperysheathisfoundatthebaseofthefirstleaves.

Juvenile–Twininggrowthhabit,slenderstembranchesnearthestem.Tanglingwithcropscancauselodgingandmakeharvestdifficult.

Mature–Greenishpinkflowersareproducedinaxillaryandterminalclusters.

Fieldbindweedandwildbuckwheatareoftenconfused.Thecotyledonsoffieldbindweedareround,leaveshavearoundedtip,lackssheathatthestemnodes,andhasatrumpet–shapedflower.


Redroot Pigweed

Redrootpigweedisacommonweedofcultivatedfields,gardens,andwasteareas.Thisweedhasanextendedgerminationperiod,growsrapidly,andhasahighrateofseedproduction.Redrootpigweedthrivesandcanquicklyout-competesufferingcrops.

Quick ID

Seedlings–Longnarrowcotyledons.Firsttrueleaveshaveanotchedtip,intowhichthemidribextendsasasmallbristle.Thecotyledonsandfirsttrueleavesareredontheunderside.Thetaprootandstemsarealsored.

Juvenile–Erectstems,usuallyhairyandgreennearthetopoftheplantwhilegreenandsmoothnearthebase.Theleavesarediamondshaped,withentiretoslightlywavymargins.Prominentwhiteveinsontheundersideoftheleaf.

Mature–Tinygreenflowersdevelopinbristlyspikesatthetopoftheplant.Theylookandfeelbristly.

CONTROL TIPS

Controlofredrootpigweedisrequiredcontinuallythroughoutthecroprotation.Authorityhasexcellentcontrolandcanbeusedinreducedandnotillagesystems.TheCLEARFIELDandExpressSunsystemsalsoachieveexcellentcontrol.ConsultthecurrenteditionoftheGuidetoCropProtectionforproductinformationandapplicationtips.Inter-rowcultivationorinter-rowhoodedsprayerapplicationscanalsobeemployedforcontrol;chemicalcontrolismostefficaciouswhenmadepriortothe4-leafstage.

Figure 66. Mature redroot pigweed plant

Figure 67. The underside of Redroot pigweed seedling leaves are red.

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66

CONTROL TIPS

Manyofthepre-seedherbicidesregisteredforsunflowersachievegoodcontroloffalseragweed.Glyphosateburndownatplantingandcultivationarethemostcommoncontrolmethods.Althoughitusuallygerminatesbeforethecrop,acoolspringcandelaygermination.Fewpost-emergentcontroloptionsareavailable.CLEARFIELDsunflowersutilizingOdysseyachievesgoodcontrolandhasresidualactivityforprolongedcontrol,butnotaslongassomeother“imi”herbicides.Cautionisneededwithuseofresidualherbicidesanditisimportanttomanageacroprotationtoavoidplantinganimi-sensitivecropwithintherecommendedtimeperiod.SeetheGuidetoCropProtectionformoredetails.

Figure 68. Mature false ragweed plant.

Figure 69. False ragweed seedling leaves are hairy.


False Ragweed

Alsoknownasmarshelder,falseragweedisarobust,competitiveannualweedofroadsidesandwasteareasthatcangrowupto2mtall.Itproduceslargeamountsofpollencausinghayfever.Whennotinflower,falseragweedresemblessunflowers.

Quick ID

Seedling –Cotyledonsareovalandstalked.Thefirsttrueleavesareopposite,variablylobedwithasoft,hairytexture.

Juvenile–Stemsaresmooth,muchbranchedanderect.Lowerleavesareoftenthree-lobedwhereastheupperleavesarebroad,almostheart-shaped,withcoarseirregular-toothedmargins.Leavesarecoveredwithhairsonbothsurfaces.

Mature–Small,greenishwhiteflowersinbranchingclustersatthetopoftheplant.

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69


Green and Yellow Foxtail

AnnualsintroducedfromEurope,greenandyellowfoxtailareseriousweedsofcultivatedcrops,gardensandroadsides.Seedsgerminatethroughoutthegrowingseasonwheneverconditionsarefavorable,makingcontroldifficult.

Quick ID

Green Foxtail

Seedling–Thefirstleavesarearchedandhairless.Baseoftheseedlingisoften reddish.

Juvenile-Leafbladesareflatandlightgreen.Themarginsanduppersurfaceofleafbladesmayfeelslightlyroughtothetouch.Theligule(membraneattheinnerbaseoftheleafwheretheleafattachestothemainstem)hasanunevenfringeofhairs.Auriclesareabsent.

Mature–Soft,greenorpurple-tingedbristlyspike-likepanicleresemblesabottlebrush.

Yellow Foxtail

Seedling –Arched,hairlessearlyleaves.Baseoftheseedlingisoftenreddish.

Juvenile –LeafbladesareflatorV-shapedandlooselytwisted.Bladesarehairlessexceptforlong,kinkyhairsontheuppersurfaceoftheleavesnearthebaseoftheblade(completelylackinginGreenfoxtail).Auriclesareabsent.Liguleisafringeofhairsabout3mmlong.

Mature–Spikeletsarelargerthanthoseofgreenfoxtail

CONTROL TIPS

Pre-plantherbicideoptionsareavailablethatcanprovidegoodtoexcellentcontrolofboththeseweedspecies.Post–emergentherbicidesareavailablethatprovideexcellentcontrol.ConsultthecurrentissueoftheGuidetoCropProtectionforcontroloptions.Maintainingwatervolumeisimportanttoachieveadequatecoveragesincetheleavesarenarrow.

Figure 70. Green foxtail seedling have light green leaves and are completely hairless.

Figure 71. Collar region of Yellow foxtail has long hairs on the upper leaf surface.

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60|Appendix

REFERENCESArthur,A.P.,andY.M.Powell.1990.Descriptionofthelast-instarofCochylis arthuriDang(Lepidoptera:cocylidae)andcharactersforseparatingiffromlast-instarlarvaofCochylis hospesWalsingham.Can.Ent.122:627-631.

Berglund,D.R.2007.SunflowerProduction.NDSU.Fargo,N.D.

Bubar,C.J.,S.J.McCollandL.M.Hall.2000.WeedsofthePrairies.AAFRD.

Friskop,A.S.MarkellandT.Gulya.2009.DownyMildewofSunflower.NDSU.http://www.ag.ndsu.edu/pubs/plantsci/rowcrops/pp1402.htm

Royer,F.R.andR.Dickinson.1999.WeedsofCanadaandthenorthernUnitedStates.UOA.


NOTES

Documents

Read the Sunflower Production Guide