Elsinoe panici Tiffany and Mathre is widespread on native Panicum virgatum L. in Iowa. In June Sphaceloma (imperfect stage) conidia develop from acervuli on overwintered stromata of wind-dispersed leaf litter and culms. Germ cubes penetrate between epidermal cells of young leaves, and 2 wk later tiny yellowish, subepidermal stromata are visible. Secondary conidia develop from acervuli on these stromata within 2 wk and are spread to adjacent leaves. Stromata become black, raised, shiny, ovoid-elongate patches, composed of thick-walled pseudoparenchymatous cells. Chlorosis or necrosis does not develop around the stromata. Stromata are visible on all leaves throughout the season. Acervuli, appearing as white spots in black stromata, open by irregular tears in the epidermis. Ascostromata develop on lower leaves infrequently from late July into September. They are tan-bronze, raised, ovoid-elongate, softer, and more loosely structured than stromata. Asci mature at different times. Ascospores are discharged from the bitunicate asci and germinate directly by budding or by germ tubes
