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Calcium Suppression of Electrolyte Loss from Pepper Leaves Inoculated with Xanthomonas vesicatoria. A. A. Cook, Department of Plant Pathology, University of Florida, Gainesville 32601; R. E. Stall, Department of Plant Pathology, University of Florida, Gainesville 32601. Phytopathology 61:484-487. Accepted for publication 16 November 1970. DOI: 10.1094/Phyto-61-484.

Suppression of electrolyte loss from inoculated leaves of Capsicum annuum cultivars hypersensitive and susceptible to race 2 (pepper strain) of Xanthomonas vesicatoria was obtained using inoculum (108 cells/ml) prepared with 0.2 n calcium nitrate. Lower concentrations of calcium nitrate in inocula were progressively less effective. No detrimental influence of any concentration of calcium nitrate used on viability of bacteria in vivo was detected. Comparable results were obtained when calcium nitrate in corresponding concentrations was injected into hypersensitive pepper leaves 16 hr prior to inoculation with bacteria. The chloride forms of calcium and strontium, but not magnesium, were as effective as calcium nitrate. Pretreatment of test leaves with 103 m or lower concentrations of uranyl acetate did not suppress electrolyte loss as effectively as calcium. Calcium was generally ineffective in suppressing electrolyte loss from hypersensitive and susceptible leaf tissue treated with ammonia or volatile substances from bacterial cultures.