Characterization of Bacillus subtilis and management of wilt of pigeonpea caused by Fusarium udum

Five isolates of Bacillus subtilis from rhizospheric soil of wilt infected pigeonpea plants, viz. Bs1, Bs2, Bs3, Bs4 and Bs5 showed +ve reaction towards all the biochemical tests except HCN, IAA and siderophore production. These isolates were evaluated for their antagonistic ability to reduce incidence of pigeonpea wilt. Isolate, Bs5 was found most effective against Fusarium udum which recorded 48.12% mycelial growth inhibition in dual culture method. Under green house studies, the isolate Bs5 recorded minimum wilt incidence (24.05%) with maximum wilt reduction (75.95%) whereas the other isolates recorded 46.16 to 71.80% wilt reduction. Thus, Bs5 was found most effective isolate for controlling wilt of pigeonpea. Minimum number of colonies (9.75 x 104/g of soil) of Fusarium udum was observed in the soil inoculated with efficient isolate of Bacillus subtilis, Bs5.