Control of Bacterial Spot of Pepper Initiated by Strains of Xanthomonas campestris pv. vesicatoria That Differ in Sensitivity to Copper. G. M. Marco, Graduate Research Assistant, Department of Plant Pathology, University of Florida, Gainesville 32611. R. E. Stall, Professor, Department of Plant Pathology, University of Florida, Gainesville 32611. Plant Dis. 67:779-781. Accepted for publication 13 December 1982. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-779.

Differences in sensitivity to copper were detected among strains of Xanthomonas campestris pv. vesicatoria. Sensitivity was judged on the basis of viability of cells after exposure to copper solutions. The solutions were obtained from suspensions of fixed copper in water of pH 7.0–7.5. The amounts of copper in solution in the suspensions were 1–2 mgL^-1. Adding mancozeb to a suspension of the fixed copper increased soluble copper to about 13 mgL^-1. Strains sensitive to copper were killed by both solutions, but copper-resistant strains were killed only by the higher amount of soluble copper. In the field, sprays of fixed copper controlled sensitive strains only. Sprays of the copper-mancozeb mixture controlled both strains of the bacterium but greater control of the copper-sensitive strains was obtained.