Potential Biocontrol Agents of Corn Tar Spot Disease Isolated from Overwintered Stromata.

Tar spot disease in corn, caused by , can reduce grain yield by limiting the total photosynthetic area in leaves. Stromata of are long-term survival structures that can germinate and release spores in a gelatinous matrix in the spring, which are thought to serve as inoculum in newly planted fields. In this study, overwintered stromata in corn leaves were collected in Central Illinois, surface sterilized, and caged on water agar medium. Fungi and bacteria were collected from the surface of stromata that did not germinate and showed microbial growth. Twenty-two isolates and three isolates were collected. Eighteen bacteria, most frequently and species, were also isolated. Spores of , , and (formulated as a commercial biofungicide) reduced the number of stromata that germinated compared to control untreated stromata. These data suggest that fungi collected from overwintered tar spot stromata can serve as biological control organisms against tar spot disease.