The bark covering swollen cankers is usually loose at the ends of the canker. Trees die back above the canker and may sprout below it. Frass and webs from secondary insects are common under loose bark. Cracking and fruiting bodies on chestnut. Basal cracking caused by chestnut blight fungus.
Cankers kill the cambium and girdle the stem.
Multiple cankers on infected trees are common. Current research is targeted toward finding a blightresistant species and the further development of the hypovirulent strains of the fungus. These strains tend to inactivate the pathogen and promote healing, but only when applied directly to developing cankers.