Cladorrhinum foecundissimum: A potential biological control agent for the reduction of Rhizoctonia solani

The effect of bran preparations of the potential biocontrol fungus Cladorrhinum foecundissimum on the survival and saprophytic growth of the soilborne plant pathogen Rhizoctonia solani in soils and soilless potting mix and on its ability to reduce incidence of damping-off of sugar beet, eggplant and pepper caused by this pathogen was investigated. Bran inoculum of isolate Cf-1 of C. foecundissimum incubated for as long as 17 days did not reduce survival of the pathogen on R. solani-infested sugar beet seed in a loamy sand (LS) or sandy clay loam (SCL), but bran inoculum of Cf-1 older than 6 days prevented growth of the pathogen from the beet seed into soil. The saprophytic growth of R. solani applied as a soilless mix-cornmeal inoculum was also prevented by isolate Cf-1 in 4 different soil types. All 4 isolates (Cf-1, ATCC 62373, CBS 181.66 and CBS 182.66) of C. foecundissimum also prevented saprophytic growth of R. solani in LS when inoculum of the pathogen consisted of a soilless mix supplemented with cornmeal. 10-Day-old bran inoculum of isolates Cf-1 and ATCC 62373 prevented sugar beet damping-off caused by R. solani in LS after 4 wk of growth. Use of Cf-1 resulted in stands (>90%) greater than those in non-infested control soils. On the contrary, use of isolates CBS 181.66 and CBS 182.66 resulted in stands less than those in pathogen-infested soil. Bran preparations of isolates Cf-1 and ATCC 62373 prevented damping-off of eggplant and pepper in soilless mix and, depending on the rate of inoculum used, resulted in stands comparable to those in pathogen-free soilless mix.