author(s)
Shiva Nagendran, Selvam Kulanthaivelu and Thiruvudainambi Sundararajan

abstract
Among the fungal diseases of rice, sheath blight caused by Rhizoctonia solani Kühn. is a major constraint hampering to rice production during the past two decades causing heavy yield loss in India. Biological control agents have been effective in recent years for numerous pathogen/host systems to enhance the plant growth and controlling the plant diseases. Several studies were experimented to identify antagonistic potential of microbial bio agents against sheath blight of rice incited by R. solani. In our study, the sixty rhizosphere bacterial strains tested against sheath blight (R. solani) pathogen under in vitro conditions, among the bacterial strains, Pseudomonas fluorescens Tu(Pf)19 and Kk(Pf)24 and Bacillus subtilis Tn(Bs)7 and Kk(Bs)19 showed maximum inhibition of the mycelial growth and sclerotial germination of R. solani. Likewise, the volatiles and crude antibiotics from these strains were also effective against the mycelial growth of the pathogen under in vitro. The effective antagonists were tested under pot culture and field experiments using the rice variety TPS5. The treatment (T1) comprising seed treatment + seedling dipping + soil application + foliar spray of bio formulation of Pseudomonas Tu(Pf)19 showed the maximum sheath blight disease reduction (75% and 47.59%) over the control.