Venturia Leaf and Shoot Blight of Aspen and Poplars Plant Pathology Venturia Leaf and Shoot Blight of Aspen and Poplars Leaves and shoots of aspen and poplars may be infected by species of the fungus Venturia. Disease development is favored by wet spring conditions. Leaf symptoms are evident in May. Irregular brown or black spots form, causing leaves to appear deformed.
Infected shoots turn black, brittle, and bend over to resemble a shepherd's crook.
Only young shoots and leaves are susceptible. As the season progresses and tissues mature, they become resistant. Death of shoots reduces height growth and can deform small trees by causing bends in the stems. Repeated attacks by the fungus can weaken trees and allow attack by other organisms. The fungus overwinters in infected shoots.