Disease could cost black walnut industry millions, forest specialist warns

Thousand cankers disease has been confirmed in Colorado, New Mexico, Arizona, Vermont, Nevada, California, Idaho, Washington, Pennsylvania, Tennessee, North Carolina and Virginia. Several quarantines have been established in an attempt to prevent the disease from spreading. States in quarantine include Kansas, Oklahoma, Nebraska, Missouri, Arkansas, Illinois, Indiana, Ohio, Michigan, Wyoming and Montana.

"It's an interesting disease that requires two parts," said Ryan Armbrust, a forest health specialist with the Kansas Forest Service. "There's a small walnut twig beetle that will feed on the twigs of black walnut trees. In doing this, it will spread a fungus that causes cankers and causes the tree's vascular system to clog up and die."

The beetle is tiny -- about the size of the letter "i" in the word Liberty on a dime. The flight season for the beetle is typically in the warmer months, but it can survive in the tree throughout the year. Since there are currently no viable treatment options, Armbrust says the best defense is to avoid moving black walnut tree firewood or lumber out of an area, especially if it still contains the bark.

"While it may seem safer to move black walnut material in the wintertime, when the beetle isn't flying around, that beetle could still be contained within that bark. When it warms up in the spring, it could come out," Armbrust said. "There really is no safe time of year to move black walnut lumber, especially from an area that has been infested."

Kansas is home to about 25 million black walnut trees, which are an important part of the economy. The Kansas Forest Service estimates the state would lose at least $160 million in revenue from the lumber and nut production if these trees were destroyed by thousand cankers disease.