CHERRY LEAF SPOT
Cherry leaf spot
Photo: U of MN Department of Plant Pathology
Cherry leaf spot, often called shot hole disease, occurs on cherry, chokecherry, and plum. This disease is caused by the fungus Blumeriella jaapii, previously known as Coccomyces hiemalis.
In the spring, spores are produced on fallen leaves that were infected the previous year. These spores are rain- splashed to susceptible leaves, causing new infections. Initial symptoms appear as reddish to purple spots on the leaves. After several days, the spots turn brown and may coalesce. Infected leaves may form an abscission layer around the fungal leaf spots. This layer causes the leaf spot to separate and drop out of the leaf, forming a "shot hole". Heavily infected leaves may eventually turn yellow and fall from the tree.
Control measures for cherry leaf spot should include sanitation. Raking leaves in the fall and pruning dead or dying branches helps to reduce the number of new infections the following year. On ornamentals, the disease seldom causes serious damage and no chemical control is necessary. However, severe defoliation can cause reductions in fruit quality, yield, and plant vigor. Therefore fungicides may be necessary on edible fruit trees. Captan and chlorothalonil are registered for use on cherry trees. Read and follow all label directions.
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Chad Behrendt, Crystal Floyd