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PEST MANAGEMENT 5 Five Notorious Tree Pests W By Don Grosman, Ph.D. ith the ever-increasing trade around the world, more and more insects, diseases and weeds are finding ways to come to America. Most travelers do not survive the trip, let alone become established in this new land. Unfortunately, several have found the right conditions (temperatures, moisture, hosts, etc.) to become established, and a few have been able thrive, multiply and have a significant impact on tree health.This article will present some information about five of the more notorious insect pests currently attacking and killing trees in the United States. Hemlock Woolly Adelgid The Hemlock Woolly Adelgid (HWA, Adelges tsugae) is a true bug native to East Asia that feeds by sucking sap from hemlock and spruce trees (Tsuga spp.; Picea spp.). In eastern North America, it is a destructive pest that poses a major threat to the Eastern Hemlock (Tsuga canadensis) and the Carolina Hemlock (Tsuga caroliniana).It was accidentally introduced into western North America from Asia in 1924. HWA was later found in the eastern United States, near Richmond,Va., in 1951.The pest has now been established in 11 eastern states from Georgia to Massachusetts, causing widespread mortality of hemlock trees. The earliest visible sign of HWA is the presence of white, cottony masses, usually located on the twigs and at the bases of the needles. Populations tend to be denser in the lower limbs,but can be anywhere on Hemlock Woolly Adelgid Photo courtesy of USDA Forest Service - Region 8 - Southern Archive, USDA Forest Service, Bugwood.org 6 Arbor Age / May/June 2013 the tree. Feeding damage results in a gradual fading and browning of limbs, often starting at the tips and progressing down the limb, until the limb eventually dies. Symptoms will progress to increased fading, thinning and dying limbs, with die-off beginning at the base of the tree and moving upward. Left untreated, the death of the tree normally occurs within three to four years. Asian Longhorned Beetle The Asian Longhorned Beetle (ALB, Anoplophora glabripennis) is a destructive wood-boring pest of maple and other hardwoods.ALB was first discovered in the United States on several hardwood trees in Brooklyn, N.Y., in 1996.ALB is believed to have been introduced into the United States from wood pallets and other wood packing material accompanying cargo shipments from Asia.ALB was later detected in Chicago (1998), northern New Jersey (2002 and 2004),Worcester, Mass. (2008), Suffolk Co., Mass. (2010), and, most recently, Clermont Co., Ohio (2011). Symptoms of ALB infestation are similar to symptoms of many pest infestations, including yellowing leaves, and dieback of branches. Specific signs include bleeding wounds in the trunk or large limb bark, indicating oviposition of eggs.There may also be large (3/8-inch), perfectly circular holes in the trunk or large limbs and frass (sawdust) on the ground near the holes.The beetles themselves may also be visible during mid to late summer months, feeding in the canopy. Asian Longhorned Beetle Photo by Dean Morewood, Health Canada, Bugwood.org www.arborage.com