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Coryneum Blight (Shot-hole Blight)
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Hosts:
- peach
- nectarine
- apricot
- tart and sweet cherry (rare)
Description:
This is a common fungal disease in Utah. It attacks dormant leaf buds, blossom buds, leaves, fruit, and twigs. The first visible lesions occur on young leaves as small, round, purplish-black spots. Eventually these infections fall out, leaving round holes, and giving this disease its name. Circular lesions later develop on fruit that first appear as reddish spots, and later as rough, corky bumps. Sometimes they are sunken. On peaches, affected buds may die and appear to be “varnished” due to gummosis. Infections may girdle twigs.
Management: Prune and destroy all infected plant tissue. Prevent irrigation water from wetting leaves. For severe infections, apply copper spray in fall starting at 50% leaf drop to protect newly forming buds, and use chlorothalonil 1 to 2 times before shuck split stage.
Precautionary Statement: Utah State University Extension and its employees are not responsible for the use, misuse, or damage caused by application or misapplication of products or information mentioned in this document. All pesticides are labeled with ingredients, instructions, and risks, and not all are registered for edible crops. “Registered use” pesticides may only be applied by a licensed applicator. The pesticide applicator is legally responsible for proper use. USU makes no endorsement of the products listed herein.