Feibert, E.

McKamey, S.

Royce, L.

Shock, C.

Simko, B.

Undetermined

ScholarsArchive@OSU

Section VmMites and Sap Sucking InsectsTHEWILLOWSHARPSHOOTERGRAPHOCEPHALA CONFLUENS (UHLER)NEW PEST IN POPLAR TREE PLANTATIONSB. Simko1, EFeiberr2, C. Shock2, L.Royce3, and S. McKamey4(1)OSUMalheurCountyExtension Office, Ontario, OR 97914,541.881.1417 (2)OSUMalheurExperiment Station, Ontario, OR97914,541.889.2174, (3)OSU, Department ofEntomology,Corvallis OR97331 (4)USDAARSSystematic Entomology Laboratory, Washington DC20560Ben.simko@orst.edu erik.feibert@orst.eduIntroductionPoplar treeplantings arebeing explored asanalternative forest products commodity in theTreasureValley of eastern Oregon andSWIdaho. Damaging infestations ofa species of leafhopper,Homoptera: Cicadellidae, were observed ina poplar treeplantation (hybrid ofPopulus deltoides xPopulus nigra) located attheO.S.U. Malheur Experiment Station (MES) during the1999-2001growingseasons. 1999 was thethird growing season ofthetrees andfirst yearoftheobserved infestation bythisnew pest. The damaging impacts ofthe insect were under estimated and the infestationwas not treateduntil September4.Thehigh population densities andfeeding bytheinsects injured leafbuds andcaused noticeable stunting oftreebranch terminals andwhole trees during 1999-growth cycle. In2000theleafhoppers were detected andtreated much earlier in theseason. Residual stunting oftrees wasobserved even through the2001 season from theprevious year's insect activity. During allthree yearsleafhopper outbreaks were treated at least onceper seasonwith aerial applied insecticides. Commercialpoplar growers inthe western Treasure Valley also reported observing andtreating for leafhopperinfestations over thelast three years. The purpose ofthis studywas toidentify thespecies ofcicadellidsandconduct preliminary observations onsamplingmethods andpopulation dynamics oftheinsectduring the2001 season. The outbreak ofthis insect and itspotential pest status incommercial poplartreeplantations havenotbeenpreviously reported in thePacific Northwest.MethodsInMay2000 insects were collected andsent first totheO.S.U. Department ofEntomology andthenforwarded tothe USDA, ARS Systematic EntomologyLaboratory inWashington D.C. S. McKameyofthe ARS SELmade the speciesdetermination.During the2001 season, sampling methods were tested at theO.S.U. MES, nearOntario, ORina 5-acre poplar tree plantation. Sampling methods included 1)aerial sweeps ofthe tree canopyusing alarge net with 15-foot extension handle. 2)visual inspections offoliage onthe epicormic branches(trunk sprouts) from the lower trunk and 3) use ofyellow sticky Apple Maggot (AM) traps suspendedfrom the lower branches ofthe tree canopy. All samplingmethods were replicated and conducted onaweekly basis from April 1toJuly 31 during the 2001-growing season. The sticky traps were used tomonitor adult population levels. Aerial net and leafobservations recorded both adult and nymphalpopulations levels ofthe leafhopper. Sampling and observed population trends assisted intiming ofinsecticide treatments to theplantation.IllResultsSpecies Identification: ARS SELidentified theleafhopper as Graphocephala confluens (Uhler). Theunofficial commonnamedesignation istheWillow Sharpshooter (WS). A literature search resulted inadearth of papers which mention this species and virtual noinformation about thespecies' pest statusinpoplar trees. Hardy (1942) observed this insect, using thesynonym Cicadella hierogtyphicavar.confluens (UhlerJ, "as anuisance due toabundance" totheresidence ofWhite Swan, WA. He goesontodescribe theprobable host for theinsect aswillow trees inanearby riparian habitat. More recentlyG. confluens (synNeokolla confluens) has been implicated as avector of plant pathogens includingPierce's disease (Frazier and Freitag, 1946) (Wolfe, 1955) (Purcell, 1980). The possible existence of aleafhopper vectored plant pathogen infecting thepoplar trees and contributing to theobservedsymptoms in the plantation is currently understudy.Sampling Methods: Of thethree sampling methods theyellow AM sticky traps appeared mostuseful indetecting adult population trends ofWS intheplantation. Thenumbers peaked onMay 29and June 6withaverage adults perweeklytrap collection at 16 and 17 WS respectively (Figure 1). Theaerial netsweepsamples onlyrecovered trace levelsthrough outthe sample period. Observations ofthe leaves onepicormic branches (trunk sprouts) detected ahatch of small nymphs, which coincided, with the trapcatch peakofJune 6. Aerialtreatment ofthe plantation withWarrior insecticide at3.8-oz formulationperacre was applied on June 11. Control wasexcellentandonly trace levelsofWS were observedduring theremaining sampling period through July 31. Noadditional infestations occurred during the2001 season. Although theaerial netcounts were lowduring the2001 season, theauthors speculatethat because ofthetimelyand effective insecticide treatment, populations ofleafhoppers didnotbuildupto levels observed inthe'99and '00 seasons. Aerial samplingwould most likely have caught adultinsects as theyspread tothe upper tree canopy during those seasons. Under theconditions of this studyit appears that yellowsticky AM traps maybeauseful sampling tool to predict population trends ofadultWillow Sharpshooter, forecast early detection of the first nymphal hatch and help effectively timeinsecticide applications.Figure 1. Willow Sharpshooter (WS) Weekly Trap Catches. (Yellow AM Trap) in PoplarPlantation. OSU Malheur Experiment Station. Ontario. OR 200120^18| 16"3.2 1412S 10£ 8"2 6< 2Firstbig hatchofnymphs observedon lower epicormic branches June 6Warrior insecticide applied 3.8 oz/ac June 11Vv >* J* J* j# >* J>% >* J .#% >* & J? J> J? Vvij> ij> J? if 4? if it r r jr p jf <$? & & *<*%* %* # # & V w %• «• »• %• «r v tf «f v112•Literature CitedHardy, D.E. 1942.ANoteonLeafhopperAbundance, p.34Journal oftheKansasEntomologicalSociety, vol.15, No. 1.Frazier,N.W. andJ.H. Freitag. 1946. Ten AdditionalLeafhopper Vectors ofthe Virus CausingPierce'sDiseaseofGrapes. Phytopathology, vol.36pp. 634-637.Wolfe H. R. 1955. Relationship ofLeafhopperNymphs to theWestern X-Disease Virus. Journal ofEconomicEntomology, vol.48,No.5, pp. 588-590.Purcell, A.H. 1980. AlmondLeafScorch: Leafhopper andSpittlebug Vectors. Journal ofEconomicEntomology, vol. 73, No. 6, pp. 834-838.113

The willow sharpshooter Graphocephala confluens (Uhler) new pest in poplar tree plantations

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The willow sharpshooter Graphocephala confluens (Uhler) new pest in poplar tree plantations

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