Journal of Agricultural Technology 317 Anti-bacterial activity of Caesalpinia coriaria (Jacq.) Willd. against plant pathogenic Xanthomonas pathovars: an eco- friendly approach D.C. Mohana and K.A. Raveesha * . Agricultural Microbiology Laboratory, Department of Studies in Botany, University of Mysore, Manasagangotri, Mysore. India. Mohana, D.C. and Raveesha, K.A. (2006). Anti-bacterial activity of Caesalpinia coriaria (Jacq.) Willd. against plant pathogenic Xanthomonas pathovars: an eco-friendly approach. Journal of Agricultural Technology 2(2): 317-327. Powdered leaf and pod material of Caesalpinia coriaria (Jacq.) Willd. was extracted with water and successively with different solvents viz., petroleum ether, benzene, chloroform, methanol and ethanol. Anti-bacterial activity assays of all the extracts against the important phytopathogenic Xanthomonas pathovars, known to cause diseases in tomato, french bean and cotton, were carried out by cup diffusion method. Aqueous pod extract showed significant activity. Among the five solvents extracts tested, methanol extract of both leaf and pod was most active against all the test bacteria, followed by ethanol extract. Comparison of the inhibitory activity of the extracts with the antibiotics bacterimycin 2000 and streptocycline revealed that methanol and ethanol extract of both leaf and pod and aqueous extract of pod were significantly higher than that of the antibiotics tested. Phytochemical analysis of leaf and pod materials revealed that antibacterial activity is due to the presence of phenolic and acidic fraction. Further separation of active fraction resulted in the loss of anti-bacterial activity, indicating a synergistic effect of the isolated active fraction. The results suggest that C. coriaria is a potential candidate plant for the management of phytopathogenic Xanthomonas which are known to cause diseases on cotton, french beans and tomato. Keywords: anti-bacterial activity, Caesalpinia coriaria, Xanthomonas pathovars Introduction Pesticides are an essential input for preventing pre and post harvest crop losses (Mathur and Tannan, 1998; Saksena, 2001; Wheeler, 2002). Synthetic pesticides are commonly used to control phytopathogenic microorganisms (Agrios, 1997). Incessant and extensive use of these synthetic pesticides are posing serious problem to the life supporting systems due to their residual toxicity (Ferrer and Cabral, 1991; Gassner et al., 1997; Andrea et al., 2000; * Corresponding author: Raveesha, K.A.; e-mail: raveesha@sancharnet.in