Panhandle Pest Update
Dr.EdBynum,ExtensionEntomologist
TexasA&MAgriLifeExtensionService,
6500AmarilloBlvd.,West,Amarillo,TX79106
[email protected],
806.677.5600ext.612
March10,2017
VolumeIX,issue1
Wheat Pests
Withthewarmweatherwheatpestsarestar-ngtobecomeac-ve.So,nowisthe-metobescou-ngfieldsfor
thosedevelopingordamagingpestinfesta-ons.Sincewehavehadarela-velymilddrywinterwheatpest
suchasgreenbugs,birdcherry-oataphids,Russianwheataphids,brownwheatmites,andwheatcurlmites
couldbepestsofconcern.
Greenbug and Bird cherry-oat aphid
Thegreenbugandbirdcherry-oataphidaremostlikelytobefoundtogether,butoneoftheaphidsmaybe
moreabundantthantheotheraphid.Thegreenbugislightgreenandhasacharacteris-cdarkergreenstripe
downitsback.Greenbugsinjectatoxinwhenfeedingcausinglocalizedreddishspotsonleaves,butunder
heavyinfesta-onsyellowandirregularshapedpatchescanspreadacrossthefield.
Thebirdcherry-oataphidcanbeyellowish-greentoadarkgreenoralmostblackincolor.Withtheuseofa
handlenstherecanbeseenareddish-orangeareaatthebaseoftheabdomenaroundthecornicles.Feeding
fromthebirdcherry-oataphiddoesnotcauseanyvisibledamage.
Greenbug
Photo:FrankPeairs,ColoradoStateUniv.
!
Birdcherry-oataphid
Photo:ErinHodgson,IowaStateUniv.
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hNp://txppipm.blogspot.com
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Panhandle Pest Update
2
SamplingFields.Sinceladybeetlesandparasi-cwasps(shownbelow)arealsoac-venowandcouldhelp
controlaphidsnaturally,fieldsshouldbeinspectedanddecisionstotreatshouldbebasedonthreshold
levels.The“Glance’nGo”samplingsystem(hKp://entoweb.okstate.edu/gbweb/index3.htm),asdevelopedby
OklahomaStateUniversityandUSDA-ARS,isagoodtoolfordeterminingifgreenbugorRussianwheataphid
infesta-onsareattreatablelevels.Thissamplingmethodtakesintoaccountthepresenceofparasi-cwasp
mummieswhenrecommendingtreatmentdecisions.Ourstandardac-onthresholdtableforgreenbugscan
s-llbeusedfordeterminingtheneedforatreatment,butitdoesnotaccountfortreatmentcostsandvalueof
thecrop.Whenusingthisac-onthresholdtakeintoaccountthatwhenthereareonetotwoladybeetles
(adultsandlarvae)perfootofrow,or15to20percentofthegreenbugshavebeenparasi-zed,control
measuresshouldbedelayedun-lyoucandeterminewhetherthegreenbugpopula-oniscon-nuingto
increaseordeclining.
Action Threshold Table for Greenbugs
Plant Height (inches)
Number of greenbugs per linear foot
3-6
100 - 300
4-8
200 - 400
6 - 16
300 - 800
OklahomaStateUniversityalongwithSouthDakota,Minnesota,andNorthDakotahaveconductedstudies
thatindicatebirdcherry-oataphidscancausefrom5-9%yieldlossfrom20-40aphidsper-llerbeforewheat
reachesthebootstage.ThefollowingprocedureandtablefromDr.TomRoyer,OklahomaStateUniversity,can
beusedtocalculatewhenbirdcherry-oataphidinfesta-onsshouldbetreated:
Panhandle Pest Update
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Brown Wheat Mite
Ourabovenormaltemperaturesanddrycondi-onsareidealfortheheavybuildupofbrownwheatmite.They
ac-velyfeedonthewheatfoliageonclearwarmdays,par-cularlyduringthemid-a\ernoon,andlooklike
blackspecksmovingontheleaves.Atnighttheymovedowntothesoil.Adis-nguishingtraitforiden-fying
thesemitesisthefrontlegswhichareabouttwiceaslongastheirbody.Thelifecyclefromeggtoadultis
completedinjust10to14days.AllBrownwheatmitelifestagesarefemales(nomales).Theyfeedbypiercing
plantcellsintheleafthatcauses“s-ppling”leafdiscolora-on.Underheavyinfesta-onsplantsbecomeyellow,
thendryoutanddie.Whentotreatforinfesta-onsisdifficultbecausedroughtstresscanseverelyreducecrop
yields,makingtreatsuneconomical.Formostsitua-onsdrylandwheatfieldshavemoreproblemsbutwithour
Brownwheatmite,
PhotoC.Patrick
Brownwheatmitedamagetounderirrigatedfield
Panhandle Pest Update
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drycondi-onslimitedirrigatedfieldscouldbeinfested.Inthissitua-onanirriga-onshouldreducethemite
popula-onwithoutaneedforami-cideapplica-on.Whenthefieldbecomesmoisturestressedagainmites
mayre-infestthefield.Unfortunatelyagoodeconomicthresholdisnotcurrentlyavailablefordetermining
whentotreat.Aruleofthumbfortrea-nginearlyspringiswhenthereareseveralhundredmitesperfootof
row,or25-50mitesperleaf.Ifwewereabletogetaharddrivingrainthiswouldcontrolthemiteinfesta-ons.
Pest Control
Insec-cideproductscommonlyusedontheTexasHighPlainsforcontrolofbrownwheatmitesisprimarily
dimethoateand,generally,chlorpyrifosforgreenbug,Russianwheataphid,andotheraphids.Eachwillprovide
effec-vecontrolbutthepre-harvestintervalmaybeimportantdependingonharves-ngforgrain,grazing,and
cudngforforage.
Product
Rate
PHI
Chlorpyrifos4E(manydifferent
products)
1/2to1pt/AAphids(including
greenbugs,birdcherry-oataphid,
Russianwheataphids)andBrown
wheatmites
Donotapplywithin14daysofharvestforforageand
hayandwithin28daysofharvestforgrainandstraw.
Donotallowlivestocktograzeorfeedontreated
foragewithin14daysofapplica-on.
CobaltandCobaltAdvanced
(chlorpyrifosplusgammacyhalothrin)
7-13fl.oz./A(includinggreenbugs,bird
cherry-oataphid,Russianwheataphids)
andBrownwheatmites
Donotapplywithin14daysbeforeharvestforforage
andhayandwithin30daysbeforeharvestforgrain
andstraw.Donotallowmeatordairyanimalsto
grazeorotherwisefeedontreatedforagewithin7
daysa\erlasttreatment.
Dimethoate2.67
0.75to1.13pts/A(Aphids-greenbugs)
Harvestforgrain-35days
0.75to1.5pts/A(Brownwheatmites)
Donotapplywithin14daysofgrazing
1/2to3/4pt/A(Aphids-greenbugs)
Harvestforgrain-35days
1/3to1/2pt/A(Brownwheatmites)
Donotapplywithin14daysofgrazing(somelabels
donothavethisstatement)
Dimethoate4EandDimethoate400
Proaxis(gamma-cyhalothrin)
3.84fl.oz./A(greenbugandmitespp.)
2.56-3.84fl.oz./A(birdcherry-oataphid,
Russianwheataphid)
Declare(gamma-cyhalothrin)
1.54fl.oz./A(greenbugandmitespp.)
1.02-1.54fl.oz./Abirdcherry-oataphid,
Russianwheataphid)
KaratewithZeontechnology(lambdacyhalothrin)
1.92fl.oz./A(greenbugandmiteapp.)
1.28-1.92fl.oz./A(birdcherry-oataphid,
Russianwheataphid)
WarriorwithZeontechnology
(lambda-cyhalothrin)
3.84fl.oz./A(greenbugandmiteapp.)
2.56-3.84fl.oz/A(birdcherry-oataphid,
Russianwheataphid)
Donotapplywithin30daysofharvest.Donotallow
livestocktograzeintreatedareasorharvesttreated
wheatforageasfeedformeatordairyanimalswithin
7daysa\erlasttreatment.Donotfeedtreatedstraw
tomeatordairyanimalswithin30daysa\erthelast
treatment.Greenbugisknowntohavemany
biotypes.DECLAREandPROAXISmayprovide
suppressiononly.
Donotapplywithin30daysofharvest.Donotallow
livestocktograzeintreatedareasorharvesttreated
wheatforageasfeedformeatordairyanimalswithin
7daysa\erlasttreatment.Donotfeedtreatedstraw
tomeatordairyanimalswithin30daysa\erthelast
treatment.Greenbugisknowntohavemany
biotypes.KARATEwithZeontechnologyand
WARRIORwithZeontechnologymayprovide
suppressiononly.