Small, black, pepperlike structures, which are spore-producing bodies, develop in the dark brown central area. Leaf blight develops best in warm, wet weather but may become severe at any time of year. Spores are produced under favorable conditions and are blown or splashed to other surrounding leaves or plants where new infections take place. Leaf scorch or red spot, caused by the fungus Diplocarpon earliana , first appears on upper leaves of infected plants. In time, spots merge, giving infected leaves a purplish or reddish cast.
Affected leaves dry up, their margins curl upward, and they assume a burned or scorched appearance.
Scorch lesions may also develop on petioles, fruit peduncles, calyxes, flowers, and fruit. Infected calyxes appear dry, which makes fruit unattractive and lowers market value. Infected petioles may be girdled and result in death of leaves and fruit. The fungus can survive from season to season in dead leaves. Control fungal leaf diseases by planting resistant, disease-free transplants and applying protective fungicides from dormancy through harvest.