Small, brown or purple spots appear around the nodes on the lower portions of the canes. These areas turn brown, causing the leaf and flower buds to shrivel and die. Leaf lesions appear as brown wedge-shaped areas. Both diseases cause considerable damage to Michigan raspberries. The fungus can live for several years in cane debris left in the field.
Conidial infection continues through- out the growing season during rainy weather.
Wounds from pruning, insect feeding or cane rubbing are the initial sites of infection. Fruiting canes infected the previous season have light colored, cracked bark. Lateral shoots on infected canes grow poorly and may wilt and die during hot weather. To prevent infection, canes should remain dry for at least 3 days after pruning so wounds will callus. Prune out and burn infected canes in the spring.