BIOLOGICAL CONTROL OF WILT CAUSING PSEUDOMONAS SPP. BY THE USE OF LEAF EXTRACTS OF SCHIMA WALLICHII (DC.) KORTH. AND MELASTOMA MALABATHRICUM L.
Sunrit Basu Sarbadhikary and Narayan C. Mandal*
Vascular wilt is a common disease of solanaceous crops caused by many fungal and bacterial species. Two wilt symptoms producing bacterial strains VBLE3 and VBST13 were isolated from infected tomato plants. Both the strains were identified as Pseudomonas spp. by 16s rRNA gene sequence homology. The pathogenecity of the bacterial strains were also proved by reproduction of disease in pot experiments. Leaf extracts of two indigenous angiosperm species of Tripura, viz., Schima wallichii and Melastoma malabathricum showed very good antagonistic effects against both of the wilt pathogens. Prominent zones of inhibition against the pathogens were produced by both leaf extracts when tested by disc diffusion method in the range of 15 to 20 mm. Massive reduction in the numbers of colony forming units (CFU) of VBLE3 and VBST13 were also noticed when treated with these plant extracts. The Minimum Inhibitory Concentration (MIC) value of the crude extracts of Schima wallichii and Melastoma malabathricum was found to be 100 Î¼g/mL and 150 Î¼g/mL respectively for both the strains. Schima wallichii showed bactericidal and Melastoma malabathricum showed bacteriostatic mode of action against both the bacterial strains.
Keywords: Vascular wilt, pot experiment, leaf extracts, MIC, bactericidal, bacteriostatic.
[Full Text Article]