Characteristic zones are v-shaped and include a leaf edge. The fungus overwinters in old leaves, and the disease is spread by splashing rain. Little is known about this disease, and losses caused by Phomopsis leaf blight have not been measured. Leaves less than10 days old are most susceptible. Spores are produced on living and dead leaves, and are spread by splashing rain.
Spores germinate and enter the leaf through stomata on the lower leaf surface.
Young leaves are particularly susceptible. Recommendations to control leaf scorch and leaf spot are very similar. Use resistant cultivars where practical. Sprays should be applied to protect plants during periods of rapid leaf growth. Good spray coverage of both upper and lower leaf surfaces is required.