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Ecology and Epidemiology

Spatial and Temporal Aspects of Epidemics of Cylindrocladium Black Rot in Resistant and Susceptible Peanut Genotypes. A. K. Culbreath, Former graduate research assistant, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616, Current address: Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, P.O. Box 748, Tifton 31793-0748; M. K. Beute(2), and C. L. Campbell(3). (2)(3)Professor, associate professor, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. Phytopathology 81:144-150. Accepted for publication 10 August 1990. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/Phyto-81-144.

Epidemics of Cylindrocladium black rot were monitored in Martin County, NC, in 1986 and 1987. Seven peanut genotypes were used: susceptible cultivar, Florigiant; moderately resistant cultivar, NC 8C; three new genotypes selected for CBR resistance, NC Ac 18414, NC Ac 18416, and NC Ac 18417; and highly resistant breeding lines NC Ac 18016 and NC 3033. Each genotype was planted in 36 plots representing a range of inoculum densities of the pathogen, Cylindrocladium crotalariae. Disease progress was better described by the logistic model than by the mono-molecular or Gompertz models for most genotypes. Rates of disease progress, determined by regression of the logit transformation of disease incidence on time, were similar in the moderately resistant genotypes NC8C, NC Ac 18414, and NC Ac 18417 and susceptible cultivar Florigiant but were slower in NC Ac 18416, NC Ac 18016, and Nc 3033 than in Florigiant. Epidemics began 1.5–2 wk later in NC 8C, NC Ac 18416, and NC Ac 18417 than in Florigiant and were delayed further in NC Ac 18016 and NC 3033. Delay of onset of epidemics was more important than rate of disease progress in comparing effects of moderately resistant and susceptible genotypes on disease progress.