23
The Sunflower Production Guide INSECTS The following sections provide current information on management of insects, diseases, weeds and birds. Below is a growing season calendar that shows the major sunflower pest problems and time of occurrence in the northern Great Plains production area (Figure 3). Figure 3. A growing season calendar indicating time of occurrence of major sunflower pests. (J. Knodel, NDSU). 14 | Integrated Pest Management APRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER Crop Stages Weed Control Insects Diseases Birds Emergence Vegetative Bud Flowering Mature Cutworms Palestriped 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

INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

  • Upload
    others

  • View
    3

  • Download
    0

Embed Size (px)

Citation preview

Page 1: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

The Sunflower Production Guide

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

Page 2: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

CONTROL TIPS Iftheriskofwirewormdamageishigh,seedscanbetreatedwithanapprovedinsecticideforprotectionofgerminatingseedsandseedlings.ConsultthecurrentGuidetoCropProtection.Norescuetreatmentsareavailableforcontrollingwirewormsafterplanting.

Figure 4. Wireworm larvae

4

The Sunflower Production Guide

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

Page 3: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

The Sunflower Production Guide

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.

16|Insects

Page 4: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

Figure 5. Different species of cutworm larvae.

CONTROL TIPS Bestresultsoccurifinsecticideapplicationsaremadeintheevening.Sometimesitismosteconomicaltojusttreatinfestedpatchesandnottheentirefieldastherearedifferencesinsusceptibilitytoinsecticidesbetweenspeciesofcutworms.ConsultthecurrenteditionofGuidetoCropProductionforregisteredinsecticides.

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

The Sunflower Production Guide

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.

5

Insects|17

Page 5: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

Figure 6. Adult – Sunflower beetle

Figure 7. Larva – Sunflower beetle7

6

The Sunflower Production Guide

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.

18|Insects

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

Page 6: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

8

9

CONTROL TIPS Insecticideusehasnotbeenwarantedforcontrolofthistlecaterpillar.

Figure 8. Thistle caterpillar

Figure 9. Painted lady butterfly

The Sunflower Production Guide

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.

Insects|19

Page 7: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

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.

11

The Sunflower Production Guide

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.

20|Insects

10

Page 8: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

13

12

The Sunflower Production Guide

Insects|21

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

Scouting Techniques

Afieldmonitoringschemeforthisinsecthasnotbeenestablishedsinceitisnotofeconomicsignificance.

Economic Threshold – Nonehasbeendetermined.

CONTROL TIPS Insecticideusehasnotbeenwarrantedforcontrolofsunflowerbudmoth.

Page 9: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

The Sunflower Production Guide

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.

22|Insects

Page 10: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

The Sunflower Production Guide

Insects|23

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.

Page 11: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

The Sunflower Production Guide

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.

24|Insects

Page 12: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

17

15

16

The Sunflower Production Guide

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.

Insects|25

CONTROL TIPS Insecticideshavenotbeenwarrantedforcontrolofthispest.

Figure 15. Sunflower maggot larva

Figure 16. Adult sunflower maggot

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

Page 13: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

The Sunflower Production Guide

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.

26|Insects

Page 14: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

19

18

The Sunflower Production Guide

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

Page 15: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

The Sunflower Production Guide

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

28|Insects

Page 16: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

CONTROL TIPS

The Sunflower Production Guide

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.

Insects|29

20

21

Earlyplantinghelpsreduceseeddamage.Whenplantedearly,thesunflowersarecompletedanthesis(flowering)beforepeakweevilpopulationsandarenolongersusceptibletoegglaying.

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

Page 17: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

The Sunflower Production Guide

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.

30|Insects

Page 18: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

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

predatorsinthesunflowerfieldalsoconsumebothlarvaeandeggs.Minutepiratebugsfeedontheeggsandyounglarvae.Groundbeetlescandestroyabout40%ofoverwinteringlarvaeandpupae.Atleast4differentspeciesofparasitesattackthelarvaeofthebandedsunflowermoth.

2422

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.

The Sunflower Production Guide

Samplingstrategiesbasedonscoutingforadultmothsduringdaylighthoursandforeggshavealsobeendeveloped.

Economic Threshold

Ifmonitoringintheearlyeveningorearlymorning,onebandedsunflowermothpertwoplantsisareasonableeconomicthreshold.

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

Insects|31

23

Page 19: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

The Sunflower Production Guide

32|Insects

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.

Page 20: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

25 26

The Sunflower Production Guide

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

Page 21: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

30 31 32

2927 28

The Sunflower Production Guide

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.

Page 22: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

3736

33 3534

The Sunflower Production Guide

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.

Page 23: INSECTS · spotted lady beetle and the convergent lady beetle. Larvae of the common green lacewing consume both eggs and larvae. Damsel bugs and the two spotted stink bug may also

The Sunflower Production Guide

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