InsectsSP290-C

Dogwood BorerInfestation, Damage and Control

Frank A. Hale, Professor originally developed by Harry E. Williams, Professor Emeritus

Entomology and Plant Pathology

Thefloweringdogwood(Cornus florida)isoneofthemostpopularornamentalplantsinTennesseelandscapes.Nativetreesalsoflourishintheforestunderstory. Thedogwoodtreeisdamagedbythefeedingactivityofthedogwoodborerlarvaunderthebarkofthetrunkandlimbs.Inasingleyear,oneborercancompletelygirdleandkillatree4inchesindiameter,butdeathismoreoftenbroughtaboutbythecombinedactivityofseverallarvaeorbysuccessiveinfestationswithconcurrentmechanicalinjuryorpathologicalproblems.Cultivatedtreesgrowinginfullsunareusuallymoreheavilyinfestedthanthosegrowinginshadedorforestedareas. Thedogwoodborer,Synanthedon scitula (Harris),isfoundthroughouttheareawherefloweringdogwoodsaregrown.Inadditiontodogwoods,theboreralsoinfestsoak,chestnut,elm,hickory,willow,pecanandapple.Theborerinfestsawiderangeofhostplants,anddogwoodtreesmaybeinfestedfrom

avarietyofnearbyhostplants.Anativepest,theborerisknownbyseveralothercommonnames:pecansesia,nine-barkborer,woodygallborer,oakgallborerandothers. AdultmothsemergefromlateApriltomid-October,withthefirstpeakofadultactivityoccurringinmid-MayandthesecondpeakinearlyAugust.Eggsarelaidsinglyonthebark.Whenfirstlaid,theeggispaleyellowandturnsonlyslightlydarkerbeforethelarvahatches.Thefemalemaylaymorethan100eggsthatusuallyrequireeighttoninedaystohatch. Newlyhatchedlarvaeenterthrough

wounds,callousedareas,cankersorsomebrokenbarksite.Larvalfeedingisconfinedtotheinnercambiumandbark.Thedogwoodborerhibernatesinthelarvalstagewithinitstunnel.Pupationtakesplacethefollowingseason.Althoughthereisonlyonegenerationperyear,borersmaybefoundinvariousstagesofdevelopmentthroughoutmostoftheyearbecauseeggsarelaidoveraperiodofseveralmonths.

Extension

Dogwood borer damageJohn A. Weidhass, Virginia

Polytechnic Institute and State University, www.forestryimages.org

Precautionary Statement Toprotectpeopleandtheenvironment,pesticidesshouldbeusedsafely.Thisiseveryone’sresponsibility,especiallytheuser.Readandfollowlabeldirectionscarefullybeforeyoubuy,mix,apply,storeordisposeofapesticide.Accordingtolawsregulatingpesticides,theymustbeusedonlyasdirectedbythelabel.Personswhodonotobeythelawwillbesubjecttopenalties.

Disclaimer Statement Thispublicationcontainspesticiderecommendationsthataresubjecttochangeatanytime.Therecommendationsinthispublicationareprovidedonlyasaguide.Itisalwaysthepesticideapplicator’sresponsibility,bylaw,toreadandfollowallcurrentlabeldirectionsforthespecificpesticidebeingused.Thelabelalwaystakesprecedenceovertherecommendationsfoundinthispublication. Useoftradeorbrandnamesinthispublicationisforclarityandinformation;itdoesnotimplyapprovaloftheproducttotheexclusionofothersthatmaybeofsimilar,suitablecomposition,nordoesitguaranteeorwarrantthestandardoftheproduct.Theauthor(s),theUniversityofTennesseeInstituteofAgricultureandUniversityofTennesseeExtensionassumenoliabilityresultingfromtheuseoftheserecommendations.

SP290C 06-0248Programs in agriculture and natural resources, 4-H youth development, family and consumer sciences, and resource development.

University of Tennessee Institute of Agriculture, U.S. Department of Agriculture and county governments cooperating.UT Extension provides equal opportunities in programs and employment.

Themothpassesthroughfourseparatestagesinitslifecycle(egg,larva,pupaandadult).Thebasiccoloroftheadultmothisdarkblue,appearingalmostblack,withoccasionalyellowmarkingsonthebody.Thedarkthoraxismarkedwithyellowlinesandayellowpatchbelow.Theabdomenisdarkwithyellowonthesecondandfourthsegments.Thewingsaremostlyclearwithdarkscalesalongtheveinsandmarginsandaspanofaboutthree-fifthsofaninch.Dogwoodborermothsareinthesamefamilyofclearwingmoths(sesiidae)asthepeachtreeborer,rhododendronborerandthelilacborer. Thelarvaeareoff-whitetocream-coloredwithareddish-brownhead.Thefrontthoracicsegmenthastworeddish-brownspotsontheuppersurface.Thenewlyhatchedlarvaeare1/16ofaninch,andthematurelarvaeare3/5ofaninchlong.Thepupaearelightbrownand2/5ofaninchlong.

Control Measures Dogwoodtreesmaybeinfestedinanurseryas1-,2-or3-year-oldseedlingsorasoldertreesgrowinginthelandscape.Treesshouldbeinspectedfordepressed,wetorlooseareasofbarkindicatingpossibleborerinfestationpriortopurchase. Physicaldamagetothebarkofthetrunkorlimbsfromlawnmowers,stringtrimmers,dogwoodcanker,pruningcutsorfreezingthebarkaidborerentry.Trees

thathavebeenpreviouslyinfestedhavewoundsthatprovideeasyentryforborers.Avoidphysicaldamagetothetrees. SpraythetrunkandlowerlimbscaffoldwiththerecommendedinsecticideinlateAprilandmid-Julyforfull-seasoncontrol.Applytheinsecticidefromthelowerlimbscaffold,downthetrunktothesoilline.Landscapetreescanbetreatedwithbifenthrin(Onyx)orpermethrin(Astro,PermethrinPro).Usepermethrin(Perm-Up3.2EC)orchlorpyrifos(Dursban)fordogwoodborercontrolincommercialnurseries. Ifaprotectiveinsecticidesprayisnotused,aparasiticnematode,Steinernema carpocapsae(Guardian),canbeappliedto

theinfestedtreetruckasacoarse,low-pressurespraytothepointofrunoff.MakeapplicationsduringMaythroughSeptemberwhensignsoflarvaeareapparent.

ReferencesPless,C.DandW.W.Stanley.1967.Lifehistoryandhabitsofthedogwoodborer,Thamnosphecia scitula (Lepidoptera:Aegeriidae)inTennessee.JournaloftheTennesseeAcademyofScience.42(4):117-123.

Rogers,L.E.andJ.F.Grant.1990.OccurrenceofdogwoodborerandotherselectedspeciesofclearwingborerinEasternandMiddleTennessee.TennesseeFarmandHomeScience.Issue154.TheUniversityofTennesseeAgriculturalExperimentStation,Knoxville.

Adult male

Adult female

James Solomon, USDA Forest Service, www.forestryimages.org