Thousand Cankers Disease has been found in Bucks County, Pennsylvania and Chesterfield and Henrico Counties of Virginia and the city of Richmond, Virginia. Six Counties are now part of the infested areas of Eastern Tennessee. Thousand Cankers Disease (TCD) threatens black walnut (Juglans nigra) and other members of the walnut family with decline and death caused by the walnut twig beetle (Pityophthorus juglandis) boring and subsequent infection by a Geosmithia fungus carried by the beetles. The twig beetles bore into the branches of black walnut, often by the tens of thousands, and create egg galleries within the bark. The Geosmithia fungus is carried into the bark of the tree by the beetle and forms small cankers. As the number of beetles and cankers infesting a tree increases, they may ultimately girdle branches resulting in the collapse of the foliage in the crown and finally tree death. The build-up of beetles and cankers may take several years, but once wilting of foliage or branch mortality is noted, the tree is usually dead within two or three years. (More...)
Walnut Twig Beetle and twig beetle holes on walnut branch: Kathy Kealtey Garvey, UC Davis
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