Cherry leaf spot, sometimes referred to as "shot-hole", is caused by the fungus Coccomyces hiemalis. The disease first appears on the upper side of the leaf as small, circular, purple spots. Later, the spots turn brown and form a definite boundary. After the cherry leaves become infected, they turn yellow and fall. Only a few lesions per leaf can result in leaf yellowing and defoliation. Although the disease occurs primarily on the leaves, fruit, stems, and leaf petioles may become infected when the disease is severe.
The fungus overwinters in infected leaves. The disease cycle can be broken by completely preventing the fungus from overwintering on fallen leaves. This is not feasible except for small backyard plantings. The primary approach to the control of leaf spot is use of fungicide sprays. Applications are started in the spring at petal fall. Fungicide products for the homeowner can be found at most garden centers. Look for a home orchard spray labeled for cherry. Read and follow the label instructions.
This article originally appeared in the July 19, 1996 issue, p. 123.
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