OBSERVATIONS ON THE ASCOGENOUS STAGE OF SEPTORIA-TRITICI IN TEXAS

Ascospores of Mycosphaerella graminicola, the sexual stage of Septoria tritici, were observed in a wheat field in Northcentral Texas during the fall of 1989 and winter of 1990. This was the first time the ascogenous stage was found in the State. Ascospores germinated on agar by hyphae that subsequently produced conidia similar to the conidia derived from pycnidiospores. Wheat seedling inoculations with ascospores, and conidia derived from ascospores, resulted in the development of typical symptoms and signs of septoria tritici blotch. Disease development on detached leaves initiated by ascospores required a longer incubation period and produced fewer pycnidia than disease initiated by conidia. We discuss some of the implications of these findings on epidemiological studies of septoria tritici blotch in Texas.