CLADORRHINUM FOECUNDISSIMUM - A POTENTIAL BIOLOGICAL-CONTROL AGENT FOR THE REDUCTION OF RHIZOCTONIA-SOLANI

The effect of bran preparations of the potential biocontrol fungus Cla dorrhinum foecundissimum on the survival and saprophytic growth of the soilborne plant pathogen Rhizoctonia solani in soils and soilless pot ting mix and on its ability to reduce incidence of damping-off of suga r beet, eggplant and pepper caused by this pathogen was investigated. Bran inoculum of isolate Cf-1 of C. foecundissimum incubated for as lo ng as 17 days did not reduce survival of the pathogen on R. solani-inf ected sugar beet seed in a loamy sand (LS) or sandy clay loam (SCL), b ut bran inoculum of Cf-1 older than 6 days prevented growth of the pat hogen from the beet seed into soil. The saprophytic growth of R. solan i applied as a soilless mix-cornmeal inoculum was also prevented by is olate 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 sapro phytic growth of R. solani in LS when inoculum of the pathogen consist ed of a soilless mix supplemented with cornmeal. 10-Day-old bran inocu lum of isolates Cf-1 and ATCC 62373 prevented sugar beet damping-off c aused 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 t he contrary, use of isolates CBS 181.66 and CBS 182.66 resulted in sta nds less than those in pathogen-infested soil. Bran preparations of is olates Cf-1 and ATCC 62373 prevented damping-off of eggplant and peppe r in soilless mix and, depending on the rate of inoculum used, resulte d in stands comparable to those in pathogen-free soilless mix.