Twig dieback may also occur, and buds may die early in the season, exhibiting symptoms that resemble frost damage. Symptoms of infection include dry, brown, irregular spots on leaves, curling foliage, and defoliation. Trees with significant dieback will be difficult to save.įor more information on two-lined chestnut borer: See UW-Extension bulletin A2902 or contact your county Extension agent.How to Identify and Manage 5 Common Chestnut Tree DiseasesĪ common disease in oak trees and other varieties of deciduous hardwoods, chestnuts may be affected by anthracnose as well. These products are best applied by a professional arborist. Systemic insecticides that are applied to trees by drenching or injection (e.g., those containing imidacloprid) can also be used for control. Cover all oak woodpiles with plastic tarps from mid-May through mid-July to limit borer movement. Remove and dispose of any two-lined chestnut borer-infested wood before beetles emerge in mid-May. ![]() Also avoid damaging the bark or allowing significant defoliation by insects such as gypsy moth, canker worm, or forest tent caterpillar. Avoid compacting soil, or changing the soil grade or water drainage pattern during construction. Water oaks (approximately one inch of water per week) during dry periods to minimize drought stress. Healthy, non-stressed trees will not attract two-lined chestnut borer adults, and vigorous trees are able to fight off invading borers. There is one generation of two-lined chestnut borer per year.Ĭontrol: The best defense against two-lined chestnut borer is prevention. Larvae feed in cambial tissue and cut off the vessels that transport food and water in the tree. Eggs are inserted into bark crevices and hatch in one to two weeks. Adult beetles emerge from trees through D-shaped holes in late May and are active until early July. Life Cycle: Two-lined chestnut borers overwinter as larvae and pupae in infested trees. Look for slender, whitish larvae and thin, random, feeding galleries (trails) under the bark. To confirm chestnut borer activity, peel away the bark on dead or dying branches or trunks. Death of a tree due to a two-lined chestnut borer infestation may take from one to five years. This girdles and kills the branches above the point of feeding. Leaf browning, and twig and branch death occur when two-lined chestnut border larvae feed under the bark and destroy the nutrient and water conducting tissues (i.e., the phloem and xylem). Symptoms include dieback at the end of branches, sparse, small or discolored foliage, or leaves that wilt suddenly, turn uniformly brown and typically remain attached to the branches. ![]() Symptoms and Effects: Two-lined chestnut borers attack many types of oaks, including red, black, white and bur oaks. Larvae are slender, legless and white, and have a small, flattened area behind their heads. They have two yellow stripes along their backs. ![]() Environmental extremes (e.g., drought), construction injury to roots, soil compaction, road salt injury, defoliation by leaf-feeding insects, storm damage and weakening from disease are all stresses that predispose trees to two-lined chestnut borer attack.Īppearance: Adult two-lined chestnut borers are elongated, greenish-black metallic wood boring beetles that are about 1/5 to 1/2 inch in length. This insect is attracted to stressed and weakened oaks. The most important insect cause of oak mortality is the two-lined chestnut borer ( Agrilus bilineatus). Phil Pellitteri, UW Insect Diagnostic Lab
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