Quarantine in Bucks aims to halt menace to walnut trees

After finding a tree infected with Thousand Cankers disease in Plumstead Township, officials have quarantined wood from walnut trees in Bucks County.

The nasty-sounding disease occurs when walnut twig beetles tunnel beneath the bark of trees. A fungus they carry produces cankers which can slowly starve a tree to death.

The disease strikes black walnut trees hardest and has been killing them in the West for years, said Bruce Moltzan of the U.S. Forest Service.

“We previously have found this in black walnut plants in the West, in some cities like Boulder and Denver,” Moltzan said.

Last year, it was identified for the first time in the East, the native habitat of black walnut trees. Its appearance in Bucks County a few weeks ago marks the first case in Pennsylvania.

“The concern is that this is the native range of black walnut, and we’re concerned that it may have a larger impact to the resource,” Moltzan said.

Moltzan said he does not know how the disease will impact local forests. State officials are stepping up surveillance for the beetle and disease as part of routine inspections.

Pennsylvania Department of Agriculture entomologist Sven-Erik Spichiger said there is no known cure for the disease and there is no way to prevent a tree from being attacked. He said it takes 10 years for an infected tree to die.

“When the Thousand Cankers disease reaches an area, mortality for black walnut, and some other walnuts as well, is almost certain,” Spichiger said. “It’s like a slow-moving version of Dutch elm disease.”

Anyone carrying walnut firewood or nursery plants out of Bucks County could face a fine of up to $20,000. Due to the difficulty of distinguishing between species of hardwood firewood, a Department of Agriculture statement said all hardwood firewood is considered quarantined.

Black walnut trees make up less than half of 1 percent of hardwood trees in Pennsylvania, but walnut is the most expensive type of lumber and an important part of the $16 billion annual wood industry in Pennsylvania.