Abstract :
Changes in prevalence, aggressiveness and sensitivity to copper and zinc bactericides of Xanthomonas campestris pv. vesicatoria races from bell pepper and tomato in Barbados since 1989-90 were determined. A total of 16 races were identified and 11 of them, including races P0, P0T1, P0T2, P1T1, P1T2, P2T2, P3T2, P4T1, P4T2, P5T2 and P6T2, were previously unreported on bell pepper and tomato in Barbados. Of the 11 races, P2T2, P4T1, P5T2 and P6T2 were detected on pepper only and T2 only was confined to tomato. Races P1T1 and P6T2, each amounting to 16% of strains from pepper, replaced race P1, which contributed 4%, as the most prevalent strains on this plant genotype. On tomato, races P1T1 and P1T2, in amounts of 36.1 and 21.0%, respectively, of the pathogen collection, replaced race T1, which represented 15.8%, as the predominant strains. Shifts from frequent association of race P1 to races P1T2 and P6T2 and from race T1 to races P1T1 and P1T2 with the greatest amounts of pepper and tomato crop damage, respectively, also occurred. The previously zinc-sensitive and copper-resistant pathogen population became resistant to zinc and reverted by 40% to copper sensitivity.
