highlights - Delaware Department of Agriculture


highlights - Delaware Department of Agriculture

West Virginia 7,546 3,517 1,566 862 755Oak Maple Hickory Pine BeechOhio 2,677 2,432 989 495 445Aerial SurveysThe southern portionof Delaware was flownin late June to detectgypsy moth, southernpine beetle, and otherdamaging agents. Whileno gypsy moth defoliationor southern pine beetleoutbreaks were recorded,surveyors made digitalmaps of several dozensites and followed upwith ground inspections.Surveyors discoveredabout 20 acres of springcankerworm defoliationof swamp chestnut oakin southern SussexCounty. They also foundapproximately 300 acreswith scattered mortalityof oak and pine. Armillariaroot rot; Ips, ambrosia,and turpentine beetles;and Hypoxylon cankerwere the most frequentlyobserved causal agents.Most of these agents areconsidered secondary,with drought stress as thelikely primary cause ofthis scattered mortality.Because drought stressis cumulative, and sinceDelaware has experienceddrought frequently inrecent years, we shouldexpect some additionalmortality in the future.Forest Species TypeOakMaplePineBeechHickory0 50 100 150 200 250million cubic feetThis map delineates aerial detection survey (ADS) results for Delaware in 2012 and 2011.2

Late instar gypsy moth larvae at a post oak infestation site of just a fewtrees at a residence in Sussex County.Spring cankerworm damage on swamp chestnut oak in Sussex County.Forest Pest IssuesGypsy MothNo significant defoliation due to gypsy moth(Lymantria dispar L.) was observed in 2012,although service foresters recorded a smallnumber of isolated infestations in SussexCounty. This marks the continuation of adownward trend in gypsy moth activity. Thewet spring may have led to increased larvalmortality caused by the parasitic fungusEntomophaga.Emerald Ash Borer (EAB)Ash represents only about 1 percent ofDelaware’s rural forests but is a significantcomponent of the urban forest in some areas.In 2012, the Delaware Forest Service usedthree survey techniques to look for emeraldash borer (Agrilus planipennis Fairmaire).First, the Buprestid-hunting wasp Cercerisfumipennis was used in a biosurveillanceprogram. Second, staff from the DelawareForest Service helped the Plant IndustriesSection service 125 purple prism trapsthroughout the State. Finally, visual surveyswere carried out at rest areas on Interstate 95and Route 1. EAB was not detected.One of the purple prism traps in Sussex County used in the emerald ashborer survey.3

Sirex WoodwaspSirex woodwasp (Sirex noctilio)presents a threat to loblolly pine,the mainstay of the forest productsindustry in southern Delaware. In2012, 20 Lindgren traps baited witha Sirex blend were hung at sevensites. Sirex has yet to be detectedin Delaware, although native Siricidswere collected.Other InsectsIn 2012, service foresters reportedlight to moderate damage frombagworm moth, eastern tentcaterpillar, borers, ambrosia beetles,Ips beetles, and fall webworm.Heavy infestations of tuliptree scalewere observed on yellow-poplarthroughout the State. The resulting sootymold and yellow jackets led to numerouscalls from frustrated homeowners.# of SPB Collected250200150100500Trap Pond2012 SPB Count by LocationCypressSwampNanticokeReddenCapeHenlopenCount 7 16 3 16 210Figure 1.—2012 southern pine beetle collection data by location.surveyed, it is unclear whether such high SPBpopulations are typical of pitch pine standsin this region, or whether this indicates apotential problem in the near future.Southern Pine Beetle (SPB)Southern pine beetle (Dendroctonus frontalisZimmerman) and loblolly pine (Pinus taeda)are both native to Delaware. Since themid-1990s, Delaware has participated inthe Southwide SPB Pheromone study thatsurveys for SPB at four loblolly pine standsin Sussex County. In light of the 21,000acres of SPB infestation in New Jersey in theprevious 2 years that occurred primarily inpitch pine (Pinus rigida) stands, a fifth sitewas added to Delaware’s SPB survey for2012. This site lies within Cape HenlopenState Park in a pitch pine stand. Somewhatsurprisingly, SPB counts at the new pitchpine survey site were more than 10 timesthe average of the other four loblolly sites(figure 1). While aerial surveys and groundinspections with park managers did notreveal any damage from SPB, the situationwill need to be monitored in coming years.Because this pitch pine stand had never beenDisease ConcernsHypoxylon CankerWidespread mortality due to Hypoxylon canker(Hypoxylon atropunctatum) was again seenthroughout the State in 2012. This pathogencauses disease only in stressed trees. Severalconsecutive hot, dry summers predisposedtrees to disease development. While manyspecies were affected, oaks, especiallysouthern red, white, and black, were mostdamaged. Service foresters again reportedthat this was the single most commondamaging agent of oaks inspected duringcalendar year 2012.Other diseasesSome damage and/or limited mortality werereported in 2012 from rust diseases, fireblight, anthracnose, and canker diseases.Moderate mortality was observed in oak andpine due to Armillaria root rot.4

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