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Disease Detection and Losses

Distribution and Severity of Peanut Leafspot in Florida. L. F. Jackson, Assistant professor, Department of Plant Pathology, University of Florida, Gainesville 32611; Phytopathology 71:324-328. Accepted for publication 24 July 1980. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-324.

Thirty-five peanut fields in seven Florida counties were sampled in 1979 for early and late leafspots caused by Cercospora arachidicola and Cercosporidium personatum, respectively. Late leafspot predominated in the sample, accounting for 88% of all leafspots counted and 66% of the leafspot area calculated. Some fields, however, had more early than late leafspot. Both high and low leafspot counts were made in fields where recommended control practices (repeated fungicide applications at 10-to 14-day intervals beginning 35–40 days after planting, and crop rotation) had been followed and also where they had not been followed. Analysis of the distribution patterns of leafspots within 12 of the fields revealed four types of distributions for both early and late leafspot. Three types of nonrandom distribution patterns and one completely random distribution pattern were detected. There was no apparent relationship between the leafspot distribution patterns and the average disease severities in the fields.