Tar spot disease in corn, caused byPhyllachora maydis, can reduce grain yield by limiting the total photosynthetic area in leaves. Stromata ofP. maydisare 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-twoAlternariaisolates and threeCladosporiumisolates were collected. Eighteen bacteria, most frequentlyPseudomonasandPantoeaspecies, were also isolated. Spores ofAlternaria,Cladosporium, andGliocladium catenulatum(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.