Potential of Bacillus amyloliquefaciens for biocontrol of bacterial canker of tomato incited by Clavibacter michiganensis ssp. michiganensis.

A total of 150 rhizobacteria and endorhizobacteria previously isolated from three different horticultural crops; strawberry, apple and apricot were screened for antagonistic activitiy against Clavibacter michiganensis ssp. michiganensis. Among them strain S1, exhibiting significantly higher antagonistic and plant growth promoting ability was characterized as Bacillus amyloliquefaciens based on morphological, biochemical and partial gene sequence analysis of 16S rRNA. B. amyloliquefaciens strain S1 showed maximum growth inhibition of C. michiganensis (12 mm). Moreover, B. amyloliquefaciens strain S1 exhibit significant phosphorus solubilization (94.16 %SEl) and indole acetic acid (27 μg ml) production under in vitro conditions. Antagonistic activity of Bacillus amyloliquefaciens strain S1 was compared with other four strains KUS1, RS, RG and AG against bacterial canker of tomato under net house conditions. Minimum bacterial canker disease incidence (30.0%) was recorded in B. amyloliquefaciens S1 followed by RG after 30 days of inoculation. The bio-control efficacy was higher in B. amyloliquefaciens S1 treated plants, followed by RG.