Root colonization potential of PGPR also determines its field efficacy in controlling soil-borne
diseases. A candidate biocontrol agent should be a potential root colonizer for successfully eliminating the pathogen in the rhizosphere. The exudates of rice roots have a significant effect on motility of PGPR towards roots (Bacilio-Jiminez, 2003). Further, Bacillus spp. has excellent root colonization potential. Management of rice ShB disease by Integral in the present investigation could be attributed to its application to seeds and roots, thereby facilitating effective root colonization and subsequent suppression of R.solani inoculum in the rhizosphere through competitive saprophytic ability.