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MAZINAIGANPAGE6SPRINGSUMMER2013Tree-chompingpeststhreatennativetreesAshmapleandoakinthecrosshairsBySteveGarskeANAForestPestEnv.GrantCoordinatorFORESTPESTSOdanahWis.Theyear1635wasanimportantoneinAmericanhistory.ThatswhenthecodlingmothwasfirstfoundinNorthAmerica.ThisEurasianmothlaysitseggsonapplespearsandcrabapples.Thecaterpillarswhichtunnelthroughthesefruitsareknowntomostpeopleasthewormsinawormyapple.Thecodlingmothmayhavebeenthefirsttree-feedinginsecttoarriveherefromoverseasbutitcertainlywouldntbethelast.By1859another17introducedtree-feedinginsectshadbeenrecordedinthecontinentalUnitedStates.Thenthingsreallytookoff.From1860through2006anaverageof2.4tree-eatinginsectpestsweredetectedeachyear.Overthesametimeperiodthenumberofhigh-impactinsectsfungiandothertreepathogensaveraged0.43peryear.Mostofthesepestsarrivedonnurseryshipmentsandotherlivingplantmaterial.Todaymorethan450tree-feedinginsectsandpathogenshavebecomeestablishedintheUS.Oneofthefirsthigh-impactpeststoarrivewasthefungusthatcauseschest-nutblight.KnownastheredwoodoftheeasttheAmericanchestnutgichi-zhaaweminandominatedforestsfromsouthernMaineandOntariotoIndianaandGeorgia.Thesetreescouldreachatleast15feetindiameterand120feettall.InJulytheywouldburstintobloomturningwholehillsideswhite.Inthefalltheirhugecropsofchestnutsgichi-azhaaweminbagaanagwouldcoverthegroundseveralinchesdeep.Thenutsfedawidearrayofwildlifefromblackbearsmakwagandsquirrelsajidamoogtoturkeysmizhisegandthenow-extinctpassengerpigeon.AbreadmadefromchestnutmealmixedwithcornwasastaplefoodoftheCherokeepeople.AfterEuropeansettlementthechest-nutplayedamajorroleintheAppalachianeconomyaspeoplegatheredthenutsasacashcropandusedthetannicacidfromthebarkintheleatherindustry.Thewoodwasstronglighterthanoakandmorerot-resistantthanredwoodandcabinsmadefromchestnutlumberinthe18thand19thcenturiesarestillstandingtoday.ThearrivaloftheAsianchestnutblightfungusintheearly1900smarkedthebegin-ningoftheendforthismagnificenttree.By1940thediseasehaddecimatedthechestnutacrossitsnativerange.Wildlifepopulationscrashedandatleastsixspeciesofmothsvanishedforever.Todaythewildchestnutpopulationconsistsalmostentirelyoftherootsystemsofsurvivingoldtreesthatshootoutgetreinfectedanddiebacktotheground.Old-growthAmericanchestnuttrees.PhototakenintheGreatSmokyMountainsofNorthCarolinaaround1910.SidneyV.Streatorphotographer.PhotocourtesyoftheForestHistorySocietyDurhamNC.RarebloomingAmericanchestnutinMassachusetts.PhotobyUSDAForestServiceSouthernResearchStationBugwood.orgCurrentfederalemeraldashborerEABquarantineareas.InsetAdultEABonpenny.PhotobyHowardRussellMichiganStateUniversityBugwood.orgWoodpeckersloveEABlarvaandpicktheouterbarkfrominfestedtreestogetthem.PhotobyKennethR.LawUSDAAPHISPPQBugwood.orgAdultEABnexttoD-shapedexithole.PhotobyJaredSpokowskyNewYorkStateDepartmentofAgricultureandMarketsBugwood.orgSeeAsianlonghornedpage7Thenextgreatwaveofdestructioncameinthemid-1900swiththedemiseoftheAmericanelmaniib.AcommonoverstorytreeineasternNorthAmericanforestselmtreesalsolinedthestreetsofmanyUScitiesandtowns.AmericanelmisattackedbyanativebarkbeetlesothearrivalofthesmallercloselyrelatedEuropeanbarkbeetleprobablywasntmuchofaproblemforit.ThenthefungithatcausesDutchelmdiseasearrivedininfestedelmlogsbroughtfromFrancein1931.Bothbeetlescarriedthefungifromonetreetothenextwipingouturbanstreettreesanddecimatingwildpopulations.FortunatelytheAmericanelmhasfaredbetterthanthechestnut.SomeAmeri-canelmtreeshavesignificantresistancetothedisease.Theelmfungusalsodoesnotspreadasefficientlyaschestnutblightwhichblowsonthewind.Thusmanyelmtreesescapethefunguslongenoughtoproduceabundantseedcrops.Throughgeneticrecombinationresistanttreescontinuetoariseandpasstheirgenesontosubsequentgenerations.HistorynowrepeatingitselfThelatestmajorpesttohitourforestsistheemeraldashborerorEAB.ThisgreeninchlongbeetleprobablyarrivedinsolidwoodpackingmaterialfromChinaintheearly1990s.Bythetimeitwasdiscoveredin2002itwaswell-establishedinDetroitandneighboringWindsorOntario.ItisnowfoundfromMassachusettswesttoMinnesotaandsouthtoMissouriVirginiaandTennessee.MostofMinnesotaWisconsinandtheUpperPeninsulaofMichiganarestillfreeoftheEABthough.TheEABattacksandkillsonlytrueashgenusFraxinusspecies.Inthecededterritoriesthisincludesblackashwiisagaakgreenashaagimaakandwhiteashaagimaakorbaapaagimaak.TheOjibweandotherGreatLakestribesvalueblackashforbasketmaking.Thewoodofwhiteashisusedforsnowshoeaagimframesandsledszhooshkodaabaanagandthebarkwanagekofallthreeisusedformedicinalpurposes.Ashisalsovaluedforhandlesfurniturecabinetryandbaseballbats.Thelossofthesetreeswouldbedevastatingtotheenvironmentandtheeconomyaswell.UnfortunatelythescenariocurrentlyfacedbyashismorelikethatofthechestnutthantheAmericanelm.TheEABattacksashsaplingsassmallasoneinchindiameterkillingthembeforetheycanproduceseed.Blackashtreesareusuallykilledwithinthreeyearswhilewhiteashtreesmaypersistforfourtofiveyears.