ABSTRACT

A total of 30 samples were collected Kancheepuram district, Tamilnadu that includes citrus fruit, leaves and stem for screening the plant pathogenic bacteria with reference to X.campestris. The bacterial isolates from the samples for the present study were confirmed as X.campestris. Among the 30 plant samples 20 isolates showed Positive for X.campestris. The bacterial isolates from the citrus plant samples for the present study were confirmed by using conventional tests. The leaves of four plant species, Aegles maromoles, Aristolochia indica, Ocimum canum, Plumbago zeylanica were collected and subjected to different solvent extractions that include ethanol, acetone, benzene, petroleum ether and alochol extraction at different concentrations of 1000 ppm, 2000 ppm, 3000 ppm, 4000 ppm and 5000 ppm. Five plant pathogenic bacteria of X. campestris pv. citri (Xcc 539, 540, 541, 542 and 543) and one X. campestris bacterial isolate from citrus plants by the agar disc diffusion method. Aegles maromoles, Aristolochia indica, Ocimum canum, Plumbago zeylanica at concentrations of 1000 ppm, 2000 ppm, 3000 ppm, 4000 ppm, and 5000 ppm showed significant activity against five plant pathogenic bacteria and one bacterial isolate. Bacteriomycin has been used as standard antibiotic reference. Zone of inhibition for all the solvent extracts in different concentrations for each of the test bacteria were recorded. The efficacy of growth inhibition of the plant extracts at each concentration showed that at 5000 ppm, the extract of Aegles maromoles and Ocimum canum showed largest inhibition zone in the acetone and alcoholic plant extracts. There is a scope to use plant extracts of the leaves of Aegles maromoles, Aristolochia indica, Ocimum canum, Plumbago zeylanica plant extracts against plant pathogenic bacteria.

Keywords : Xanthomonas campestris; Antimicrobial activity; Medicinal plants; Citrus canker.