Cherry leaf spot is caused by the fungus Coccomyces hiemalis. The disease first appears on the upper side of leaves as small, circular, purplish spots. Later, these spots turn brown and the tissue falls, leaving a circular hole in the leaf. Because of this symptom, the disease is sometimes referred to as "shot-hole" disease.
Infected leaves eventually turn yellow and fall from the tree. Only a few lesions per leaf can cause yellowing and leaf drop. When the disease is severe, fruit, stems, and leaf petioles may also be infected by the fungus.
To control the disease, rake and remove fallen infected leaves. This will help prevent the fungus from overwintering in infected leaves. Fungicides (such as Daconil 2787 or a "Home Orchard Spray" labeled for cherry) can be used to protect trees from infection. Products are typically applied 4 times at 2 week intervals starting as buds open in the spring. An additional spray is applied 14 to 21 days after harvest. Be sure to read and follow the label directions for the product used.
This article originally appeared in the July 21, 1995 issue, p. 109.