HARRISBURG, PA – Thousand Cankers Disease has reared its head in Pennsylvania again, threatening he state’s $19 billion hardwoods industry.

At risk is the state’s population of Black Walnut trees, which make up less than half of one percent of hardwood trees in Pennsylvania, yet produce high-valued lumber used in woodworking and furniture-making.

Earlier this month the Pennsylvania Department of Agriculture announced an infected walnut twig beetle was discovered in Chester County. Traces of the disease were also discovered in surrounding trees. The discovery prompted state officials to enact a wood quarantine ban for part of the state, similar to one enacted when the disease first appeared in Pennsylvania three years ago.

The disease was first detected in Pennsylvania in 2011. The disease was found on a black walnut tree in Plumstead Township, Bucks County, and reported by the property owner to Penn State Cooperative Extension.

Thousand Cankers Disease is caused when Walnut Twig Beetles, which carry a 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 disease was first diagnosed in walnut trees in Colorado in 2003, and has caused widespread death of black walnut trees in many western states. Other species such as Arizona walnut, English walnut and California walnut have shown varying degrees of susceptibility to the fungus.