Populations of Xanthomonas campestris pv. vesicatoria in Lesions of Susceptible and Resistant Tomato Genotypes. G. Cameron Somodi, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Gulf Coast Research and Education Center, 5007 60th Street East, Bradenton 34203. J. B. Jones, and J. W. Scott. Institute of Food and Agricultural Sciences (IFAS), University of Florida, Gulf Coast Research and Education Center, 5007 60th Street East, Bradenton 34203. Plant Dis. 75:357-360. Accepted for publication 19 September 1990. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0357.

Tomato genotypes resistant (R), susceptible (S), partially resistant (PR), and F₁ progeny of R × S and R × PR crosses developed bacterial spot lesions when inoculated with Xanthomonas campestris pv. vesicatoria. Bacterial populations in foliar lesions determined by direct plating (DP) and indirect immunofluorescence (IIF) from Hawaii 7998 (R) lesions were significantly less than populations in Walter (S). Lesion development in Hawaii 7998 appears to be a manifestation of the hypersensitive response, as exemplified by significantly lower populations in lesions of Hawaii 7998. Bacterial lesion populations of F₁ plants were intermediate between the two parents but not always significantly different from one or both parents. Partially resistant Campbell 28 had population levels similar to the susceptible cultivars, indicating these methods were not useful in identifying resistance from Campbell 28. A significant correlation existed between IIF and DP, and both methods were highly correlated to field infection. Thus, both procedures could be useful as corroborative tests for characterizing resistance levels of breeding lines derived from Hawaii 7998.