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Thousand Cankers Disease

Narrow tunnels and small holes in a cross section of wood.

Other names: Thousand Cankers Disease (Walnut twig beetle, Pityophthorus juglandis + Geosmithia morbida)

Plants susceptible: Walnut, Butternut

What is it?

Thousand cankers disease is caused by an interaction between a beetle and a fungus. The disease occurs when walnut twig beetles attack a tree and carry a fungus, Geosmithia morbida, with them. If either the beetle or the fungus is not present, the tree will not develop thousand cankers disease.

Why is it invasive?

Forms cankers under outer bark on branches and stems. These cankers cut the tree off from important nutrients and can eventually kill the tree.

How do you prevent its spread?

Check your walnut trees regularly for symptoms and report them if you see them. Don’t more firewood outside of a twenty mile radius of where it was collected.


♦ Thousand Cankers Disease: Indiana Walnut Trees Threatened

Seen it? Report it! Through the app, online, by email, or by phone (1-866-663-9684).

Image credit: Steven Valley, Oregon Department of Agriculture, Bugwood.org