In late 2012, a tree-killing disease called thousand cankers disease was found for the first time in North Carolina in Haywood County. The county was quarantined for the pest by early January 2013, restricting the movement of walnut wood and hardwood firewood. Now, nearly three years later, not much has changed. Despite annual surveys and trapping statewide, the disease has not been found in any additional counties in the state.
Walnut twig beetle; Image: Steven Valley, Oregon Department of Agriculture, Bugwood.org
Thousand cankers disease has already caused the mortality of countless black walnut in its invaded range. The disease is capable of spreading from tree to tree with the help of the tiny 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, leading to a mass-attack. When multitudes of beetles attack, the cankers merge together, effectively cutting off the transportation tissues of the tree. Given the countless cankers that lead to death, the name thousand cankers disease is quite fitting!
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 Virginia, Pennsylvania, Indiana, Ohio and Maryland.
Walnut twig beetle traps were set statewide in 2015. The invasive beetle was not found in any new areas. Photo: K. Oten, N.C. Forest Service.
In order to detect thousand cankers disease in new areas, traps are set statewide. Traps are meant to lure the walnut twig beetle in with a bait that mimics the scent of a declining walnut tree. Between efforts of the N.C. Forest Service and the Plant Industry Division, 184 traps were set statewide this year. No new detections of the walnut twig beetle were made.
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, untreated 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.