Spores are produced under favorable conditions and are blown or splashed to other surrounding leaves or plants where new infections take place. Leaf Scorch Symptoms. Leaf scorch or red spot, caused by the fungus Diplocarpon earliana, first appears on the upper leaves of infected plants. In time, the spots merge, giving infected leaves a purplish or reddish cast. Scorch lesions may also develop on petioles, fruit peduncles, calyxes, flowers, and fruit.
Infected calyxes appear dry and make fruit unattractive, lowering the fruit's market value.
Infected petioles may be girdled and result in death of leaves and fruit. Persistence And Transmission. The fungus can survive from season to season in dead leaves. Apply protective fungicides from dormancy through harvest. Avoid overhead irrigation if possible.