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Spatial Distribution of Cabbage Black Rot and the Estimation of Diseased Plant Populations. James Strandberg, Assistant Plant Pathologist, University of Florida, Agricultural Research and Education Center, Sanford 32771; Phytopathology 63:998-1003. Accepted for publication 15 February 1973. DOI: 10.1094/Phyto-63-998.

Spatial and temporal distributions of cabbage plants infected by the bacterium Xanthomonas campestris, and the distribution of lesions among cabbage plants were examined. The patterns of distribution of lesions per plant and of infected cabbage plants per unit area were highly aggregated. Patterns of distributions for both lesions and infected plants were best described by the negative binomial distribution and common k values of 0.15 and 0.50 were obtained for lesions per plant and infected plants per unit area, respectively. A modified sequential sampling method, based on the spatial distribution of lesions and infected plants, was used to obtain average infection rates for the black rot disease with a large reduction in time and effort. An average infection rate of 0.57 was observed. Evidence to verify the spread of black rot by farm machinery, was also obtained.

Additional keywords: epidemiology, sequential sampling, Xanthomonas campestris.