[3] It was first discovered in Wisconsin, but has since spread to other states and into Canada,[4] making the butternut an endangered species in Ontario.

Broad dead areas known as cankers form on the main stem, branches, young twigs, and exposed roots.

When the spores make contact with wounds or broken branches, they germinate and penetrate deep into the tree to produce cankers.

Many species of tree show varying degrees of resistance, such as the heartnut, butternut, and the Japanese, black, and Persian walnuts.

While standard practice has been that infected trees should be removed to prevent further spread, there is a growing opinion that the time for this is past.

Recent reports have shown that the fungus can be internally seed-borne, so seeds should be subjected to intense quarantine protocols; most especially if destined for plantings where the disease is not already established.