Any adjacent stems and leaves will develop Alternaria lesions. C. Conidia that land on stem or leaf tissue germinate and penetrate the plant. On leaves, typical lesions form. The earliest symptom of Alternaria infection is a chlorotic or yellow spot. This develops into a lesion where the oldest infected area begins to dry out, turn tan, and die.
Lesions typically have all stages of infection present.
As lesions continue to develop and spread conidia, surrounding plants become affected. Stem lesions begin to develop just above the straw. The resulting tan lesion is brittle and the stem usually bends at a sharp angle. E. Alternaria can also infect the flower and seed head. Berries that are infected late in their development will not abort but the pulp will be a source of disease.