Occasionally, tiny black pycnidia of the causal fungus develop in the center of the spot. These pycnidia can be examined with the aid of a hand lens. The pycnidia contain thousands of spores that are the source of continued infections. As leaf spots become more numerous and coalesce, leaves yellow and fall. Black Rot Fruit infection and black rot may follow frogeye leaf spot disease.
Infections usually begin in the blossom end of the developing fruit.
As the fruits enlarge, a brown decayed area appears. The decay is often characterized by a series of concentric rings alternating from black to brown on the fruit surface. Pycnidia are scattered over the surface of the decayed fruit. Eventually, the rotted fruits dry out and mummify, sometimes hanging on the tree until the next season. Thin out branches to promote good air movement.