Cryptostroma corticale

About

Cryptostroma corticale is a species of fungus that causes sooty bark disease of maples, particularly sycamore. The spores grow profusely under the bark of affected trees or stacked logs. The fungus causes disease and death in trees, and the spores are allergenic and cause a debilitating pneumonitis in humans. It is the only species in the genus Cryptostroma.

Summary from Wikipedia