Other Insects & Diseases
What's going on with the maple trees?
The spring and early summer of 2011 consisted of cool days and nights combined with excessive amounts of rainfall and not very many sunny days. These conditions were just right for infection by several fungal diseases that we saw on maple trees - primarily on norway maples. Common symptoms included: brown, black, and yellow spots on leaves; wrinkled leaves; and leaves falling prematurely.
The two primary foliar diseases responsible were “Tar Spot” and “Maple Anthracnose.” Detailed information about these foliar diseases from the UW-Extension can be found below. The presense of these foliar diseases has continued for the past several years.
Neither of these diseases is “life-threatening” to the continued health of trees. If an infected tree is in relatively good health, it can withstand these foliar fungal diseases. By the time the symptoms emerged it was late into a tree’s annual growth cycle, buds for the next year had already been produced and carbohydrate reserves were stored in the trunk and root systems of trees providing the necessary energy to start bud break and photosynthesis next year.