In vitro antibacterial Activity of Plant Extracts against xanthomonas Oryzae Pv. oryzae Causing Bacterial Leaf Blight in Rice

In the present study, an attempt has been made to use plant extracts in place of synthetic chemicals to reduce Xanthomonas oryzae pv. oryzae incidence. Accordingly, the antibacterial activity of 40 plant extracts was assessed and out of which ten plant extracts were found to have appreciable antibacterial activity against Xanthomonas oryzae. Among the plant extracts, Rhizophora apiculata at 20 per cent showed a large inhibition zone with high activity index and recorded maximum plant vigor index. This was followed by Aadathoda vesica and Punica granatum at 20 per cent concentration. The efficacy of these ten plant extracts was also tested through detached leaf assay on rice variety ADT 43. The protective treatment (before inoculation) was found to be significantly more effective than the curative treatment (after inoculation) and the most effective plant extract was found to be R. apiculata. Rice plants treated with R. apiculata developed the smallest lesion which was followed byAadathoda vesica, Punica granatum, Tamarinda indicus and Datura stramonium in the decreasing order of merit. Under pot culture conditions also, the extract of R. apiculata showed maximum efficacy against bacterial leaf blight incidence recording minimal lesion size when compared to other treatments.