C. minitans was found parasitizing sclerotia of Sclerotinia sclerotiorum on guayule from near Salinas, Calif., and on Brussels sprouts from near Carmel. In laboratory inoculation expts. the fungus was also found to be parasitic on sclerotia of S. minor, C. minitans reduced apothecia formation of 5. sclerotiorum when a spore suspension was applied to sclerotia before they were buried in sterile sand and when a spore suspension was poured on the surface of the sand after the sclerotia were buried.