Just recently, Thousand Cankers Disease has been detected for the first time in Pennsylvania, and a quarantine restricting the movement of wood from Bucks County and other states known to have the disease is effective immediately. The disease was found on a black walnut tree in Plumstead Township, Bucks County.
The State Department of Agriculture has issued an order that indefinitely prohibits the movement of all walnut tree wood from Bucks County. The quarantine includes living trees, dead wood, fallen wood, stumps, branches and mulch made from walnut trees. Because many people can’t tell one type of wood from another, all firewood in Bucks County is considered quarantined. Nuts, processed lumber and finished wood products are exempt from the quarantine. Violation of the quarantine carries penalties of up to 90 days imprisonment and fines of up to $300 per violation.
The disease is caused when Walnut Twig Beetles, which carry spores of the Geosmithia fungus, tunnel beneath the bark of walnut trees, causing small cankers to form. As more beetles attack the tree, the number of cankers increases, slowly starving the tree of nutrients and causing the tree to die within 10 years of initial infestation. There is no known cure.
The Walnut Twig Beetle is minute, only 1.5-1.9 mm. Twig beetle infestations can be diagnosed from the pitch tubes hanging from infested twigs. Early symptoms of the disease are yellowed leaves, thinning foliage in the upper crown of the tree and dead limbs. Young trees and trees that are stressed are vulnerable. Shaded and storm-damaged twigs are especially susceptible.
Since many species of wood-boring insects, including the Walnut Twig Beetle and Emerald Ash Borer, can be spread through transport of infested firewood and logs, campers and homeowners are encouraged to use only locally harvested firewood, burn all of it on-site and not carry it to new locations.
The beetles and their fungi could be “devastating” to Pennsylvania’s $25 billion hardwoods industry and have a similar effect to Pennsylvania’s black walnut trees what insects and fungi did to the American chestnut and American elm trees years ago — kill them. Black walnut trees, which make up less than half of one percent of hardwood trees in Pennsylvania produce high-valued lumber used in woodworking and furniture-making. The nuts of the trees are consumed by humans and wildlife.
Walnut Twig Beetles are native to the Southwestern U.S. and Mexico. The fungus has been found in Arizona, California, Colorado, Idaho, Nevada, New Mexico, Oregon, Tennessee, Utah, Virginia and Washington. The disease was first diagnosed in Colorado in 2003, and has killed the black walnut trees in many Western states. Other species of walnut trees, such as the Arizona Walnut and the English Walnut, are susceptible to the disease.
Any property owner in Bucks County who suspects his tree might be affected by the disease should call the Penn State Cooperative Extension in Bucks County or call the PA Department of Agriculture’s automated toll-free pest hotline at 1-866-253-7189.