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Effects of Bactericide Treatments on Bacterial Spot Severity and Yield of Different Pepper Genotypes and on Populations of Certain Insects. S. M. McCarter, Professor, University of Georgia, Athens 30602. . Plant Dis. 76:1042-1045. Accepted for publication 26 June 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-1042.

In a 3-yr study, bell pepper genotypes with different levels of susceptibility to Xanthomonas campestris pv. vesicatoria were treated with bactericides to study disease and yield responses. At Blairsville, Georgia, under moderate disease pressure, a cupric (Cu) hydroxide + mancozeb combination applied at weekly intervals provided moderate disease control and increased yields 76, 117, and 83% during 1987, 1988, and 1989, respectively, on the highly susceptible cultivar Yolo Wonder B. In 1988, at Athens, Georgia, under low disease pressure, the same treatment resulted in a 15% yield reduction on Yolo Wonder B due to stimulation of insect activity. The Cu hydroxide + mancozeb treatment also reduced disease severity on the moderately susceptible genotype C44-NV22 but significantly increased yield (21%) in only one of three years. The treatment also reduced disease on more resistant genotypes but did not increase yields. Season-long use of copper compounds alone or in combination with fungicides resulted in significant increases in populations of aphids (at Blairsville) or fall armyworms (at Athens).

Keyword(s): chemical control, host resistance, Myzus persicae, Spodotera frugiperda.