SUPPRESSION OF DAMPING-OFF CAUSED BY RHIZOCTONIA-SOLANI, AND GROWTH PROMOTION, IN BEDDING PLANTS BY BINUCLEATE RHIZOCTONIA SPP

Nine isolates of binucleate Rhizoctonia spp, from potting media and nu rsery plants, were screened for their ability to control damping-off d isease caused by Rhizoctonia solani Kuhn AG 4 and AG 8. Seedlings of C apsicum annuum L. were grown in a pasteurized potting medium in growth chambers. All isolates prevented damping-off caused by R. solani AG 4 , and most isolates increased shoot weights in the presence of either AG 4 or AG 8. Two isolates were tested further on seedlings grown in p asteurized potting medium in a glasshouse. In two experiments, both is olates controlled damping-off in Capsicum caused by AG 4. In another e xperiment, both isolates reduced damping-off caused by AG 4 in Capsicu m, Celosia and Viola seedlings, and increased shoot weights of Capsicu m and Celosia. One isolate also reduced damping-off in Petunia. Each i solate promoted shoot growth of seedlings in two of four experiments w hen no pathogen was added. As these binucleate Rhizoctonia isolates al so control Pythium, they have potential for use as biological control agents in plant nurseries.