Arborists in Colorado are rushing to implement a plan to contain thousand canker within the borders of Colorado. The disease is spread by tiny bark beetles called walnut twig beetles.

The thing that you can do is not transport fresh cut black walnut across the state border.  Recently-cut black walnuts can contain tens of thousands of the carrier beetles.

“I think thousand cankers disease has the potential to devastate black walnut just as Dutch elm disease nearly wiped out American elm and chestnut blight eliminated American chestnut,” said Whitney Cranshaw, entomologist at CSU.

“Right now it is contained in the West but all it would take is one careless individual moving a walnut log with the beetles and we could have an outbreak that could quickly spiral out of control.”

If 1,000 canker spreads to the eastern US, it could wipe out swaths of black walnuts causing millions of dollars in damage.

Our arborists have seen walnut kill east of I-25 which is a discouraging sign. In the western US, all black walnut trees descend from human planted growth.

But in the eastern US, black walnut is a native species. If thousand canker infects these forests, erosion can damage water quality and threaten nearby homes.

Colorado State University is sponsoring a survey to identify exactly where infected walnuts are located. Thousand canker is a newly identified disease but there is a consensus that it has been active for the past 15 years on the west slope.