A New Species of Coniothyrium Parasitic on Sclerotia

SUMMARY

Coniothyrium minitans was isolated from parasitized sclerotia of Sclerotinia sclerotiorum obtained from Sclerotinia-diseased guayule from near Salinas, California, and from Brussels sprouts from near Carmel. Laboratory inoculation experiments demonstrated that sclerotia of both S. sclerotiorum and S. minor were readily parasitized by the fungus and furnished suitable substrata for the development of pycnidia. In an inoculation experiment the formation of apothecia from sclerotia of S. sclerotiorum in sterile sand was suppressed when pycnidiospores of C. minitans were brought in direct contact with sclerotia and when they were poured on the surface of the sand. The results of these experiments suggest the possibility of biological control of Sclerotinia spp. by C. minitans.