Endophytic Bacillus spp. suppress Rhizoctonia solani web blight of bush cowpea

Web blight disease caused by Rhizoctonia solani Kuhn, has become a serious problem in cowpea (Vigna unguiculata (L.) Walp.) leading to drastic yield loss in the tropics. Endophytic bacteria isolated from healthy fodder cowpea and bush cowpea were evaluated for their effects on web blight disease incidence. The isolates were first screened for their in vitro antagonism against R. solani. Out of the 38 isolates screened, three promising isolates were selected and identified as Bacillus subtilis, B. amyloliquefaciens and B. velezensis. Under in vivo conditions, seed biopriming with B. velezensis CBRE5 along with its foliar application twice was found to be the best treatment for the management of web blight of cowpea with the minimum percent disease index of 32%. The present study indicated that endophytic Bacillus spp. isolated from the host plant could be used as potential biocontrol agent against web blight disease of cowpea caused by R. solani. This is the first report on management of any disease of cowpea with endophytic microbes isolated from the host plant.

Automated summary

Web blight disease caused by Rhizoctonia solani is a serious problem in cowpea, leading to yield loss. Endophytic bacteria isolated from healthy fodder cowpea and bush cowpea were evaluated for their effects on web blight disease incidence. Bacillus subtilis, B. amyloliquefaciens and B. velezensis were identified as promising biocontrol agents against web blight disease of cowpea caused by R. solani.