Photo and text used courtesy Clemson University
Cooperative Extension Service.

A characteristic symptom is the presence of many circular, brown to black spots on the leaf sheath and basal portion of the leaf blade. The spots may become so close together as to cause large black areas. Damage to the stalk may cause some lodging, especially after wind storms. Resistance in vartieties has regulated brown spot to a position of lesser importance.

The fungus survives in the soil and in old leaves and stalks. It is not seed-borne.