Abstract

Sheath blight of rice, which is caused by Rhizoctonia solani Kühn, is an economically important disease as it causes severe yield losses. Biological control of the disease by the use of fungal and bacterial antagonists is a potential substitute to the commonly followed chemical based control methods. The present investigation, conducted at the biocontrol laboratory of G. B. Pant University of Agriculture & Technology, was aimed at studying the antagonistic activity of some potential biocontrol agents viz., Trichoderma harzianum (isolates TCMS 36, TCMS 43, Th 3, TCMS 9 and Th 14), Pseudomonas fluorescens (isolates Psf 173 and Psf 02) and Bacillus sp. under in vitro conditions by dual culture technique and volatile assay method. The results from dual culture revealed that TCMS 36 showed the maximum radial growth inhibition of 69.44% followed by TCMS 9 (66.68%) and Psf 02 (65.0%). Bacillus sp. showed least per cent growth inhibition of 45.25%. Results of the volatile assay also followed the same trend as dual culture and depicted that the maximum radial growth inhibition was found in TCMS 36 (54.2%), followed by TCMS 9 (49.5%) and Th 14 (43.0%) and other isolates were found moderately effective in inhibiting the radial growth of pathogen, while Bacillus sp. was found least effective. This research concludes that the tested fungal and bacterial isolates can have an inhibitory effect on the radial growth of R. solani and can be further exploited as potential biological control agents to control the sheath blight disease of rice.