Anthracnose
A fungus that causes brown blotches on leaves of dogwoods, sycamores, maples and others, especially in wet springs. Usually cosmetic on large trees, serious on dogwoods.
Leaf spot and powdery mildew
Cosmetic problems on many trees and shrubs in humid weather. Good air movement, clean-up and sometimes fungicide help.
Oak wilt
A serious vascular disease of oaks that spreads through root grafts and insects. Avoid pruning oaks in warm months and call an arborist if leaves turn and drop early.
Cankers
Sunken, discolored areas on bark that can girdle limbs. Prune out affected wood and reduce stress.
Root and trunk rot
Fungi that rot wood, often at the base. Mushrooms and a hollow sound are warning signs. They affect safety.
Prevention
Plant right, mulch, water in drought, avoid wounds and keep trees diverse. A healthy tree is the best defense.
Learn which problems are cosmetic and which are serious, and ask an arborist when unsure.
