Epidemiology and Control of Bacterial Blight and Canker of Cowpea. R. D. Gitaitis, Associate Professors, Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton 31793. D. K. Bell, Associate Professors, Department of Plant Pathology, and D. A. Smittle, Professor, Department of Horticulture, University of Georgia, Coastal Plain Experiment Station, Tifton 31793. Plant Dis. 70:187-190. Accepted for publication 9 August 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-187.

Four major cowpea cultivars grown for processing in Georgia were evaluated in field plots for their susceptibility to bacterial blight and canker, caused by Xanthomonas campestris pv. vignicola. Analysis of disease progress curves by transforming disease ratings into gompits showed that the cultivars Pinkeye Purple Hull and White Acre were moderately resistant but Mississippi Silver and Coronet were highly susceptible. Sprays of copper and copper + maneb mixtures controlled leaf spot and stem canker symptoms and significantly increased yields. However, high levels of seedborne bacteria were detected in seed harvested from nontreated check plots. Bacteriophage typing was employed to determine the source of inoculum for seedborne bacteria in the different treatments. On the basis of the original distribution of two lysotypes in the field plots, the infestation of seed from copper + maneb treated plots was attributed mainly to interference from inoculum in check plots.

Keyword(s): Vigna unguiculata.