IN-VITRO EVALUATION OF BACTERIA FOR THE BIOLOGICAL-CONTROL OF MACROPHOMINA-PHASEOLINA

Sixty-four strains of Rhizobium and seven other rhizosphere bacteria w ere evaluated by streak-plate, double-layer, and spent-culture methods to determine their antibiotic activity against Macrophomina phaseolin a, causative agent of 'ashy stem' blight of beans. Expression of inhib ition varied among strains and depended on growth media and screening method. The streak-plate method with yeast extract/mannitol was the be st bioassay. Results indicate that root-nodule bacteria have weak biof ungicidal potential. A strain of Pseudomonas cepacia (UPR 5C) consiste ntly restricted fungal growth.