Autumn leaf discoloration – MSU Extension
As the summer gradually moves into the fall season, the leaves of many tree species will prematurely turn brown. A variety of leaf fungi are especially common when associated with cooler and moister conditions. Different fungi are associated with different tree species. Few of these leaf fungi present a health threat to individual trees or forests.
Trees began physiologically preparing for the winter season in early August. They’ve been vigorously photosynthesizing for months. Leaf and flower buds are set for 2018. Flowers and fruits are mostly done for the year. Carbohydrate reserves have been translocated to root systems and other storage areas. The shorter daylight hours will drive the color change. The early leaf-changers have already begun their color season.
It’s common to see browning leaves that present little or no health threat to trees. A number of Anthracnose species will cause the leaves of oaks, maples and other tree species to turn brown. Areas of leaves will turn brown, usually in the lower part of the crown where the air is more humid. This can be particularly common with golf courses and manicured landscapes that utilize watering systems.
