Efficacy of Enterobacter cloacae KtB3 to Control Damping-Off Disease on Soybean Caused by Sclerotium rolfsii

Abstract Damping-off caused by Sclerotium rolfsii is one of important disease on soybean in Indonesia; may cause the yield loose up to 59% when no control measure is applied. An isolate of rhizobacterium (KtB3) was tested for its potential to suppress the growth of S. rolfsii and to control damping-off disease on soybean. This isolate significantly (P<0.05) suppressed the growth of S. rolfsii on PDA medium with inhibitory activity by 96.97%. The cell-free cultural filtrate of isolate KtB3 showed obvious antifungal activity against S. rolfsii indicated by the formation of inhibition zone around diffusion wells. This result indicated that there is an antifungal substance produced and released by KtB3 into the cultural medium. The isolate KtB3 was identified as Enterobacter cloacae based on 16S rRNA gene analysis. Application of compost formula of E. cloacae KtB3 on soybean seed prior to planting significantly (P<0.05) suppressed damping off disease. Percentage of disease incidence of post emergence damping-off on soybean without formula treatment (control) was 100%, while on soybean treated with compost formula of E. cloacae KtB3 was only 12.59%. The results of this study suggested that E. cloacae KtB3 is a potential bio-agent to control damping-off disease on soybean. © 2018 Friends Science Publishers