A walnut tree with thousand cankers disease; Image: Karen Snover-Clift, Cornell University, Bugwood.org
On January 3, the department announced a quarantine that limits the movement of walnut trees and wood products in Haywood County due to the the presence of thousand cankers disease within the Great Smoky Mountains National Park.
Thousand cankers disease is a fungal disease spread by the walnut twig beetle, which bores into the tree, causing a canker to form at the point of entry. An already infested tree is very attractive to incoming beetles. When multitudes of beetles attack a single tree , cankers merge together, effectively cutting off the transportation tissues of the tree.
Symptoms, seen in the summer months, may look like individual branches dying, overall crown thinning or the tree may look like it has stunted leaves. Tree death typically occurs two to three years after symptoms develop. In North Carolina, black walnut and butternut are susceptible.
Native to the Southwestern U.S. and Mexico, thousand cankers disease was first detected in the Eastern U.S. near Knoxville, Tenn. It has since been found in areas of Tennessee, Virginia and Pennsylvania.
If you suspect a tree on your property is infected with thousand cankers disease, contact the N.C. Forest Service. Do not take samples! Long-distance dispersal of pests like these is greatly facilitated by human movement, whether intentional or not. Therefore, it is recommended that walnut trees, walnut wood products and potential samples of the disease not be transported.
More information, including ways to report the disease, can be found on our FAQ page.
Walnut twig beetle; Image: Steven Valley, Oregon Department of Agriculture, Bugwood.org