Submitted to: American Phytopathological Society
Publication Type: Abstract Only
Publication Acceptance Date: 3/9/2004
Publication Date: 6/1/2004
Citation: Walcott, R.R., Sanders, F.H., Block, C.C. 2004. A lognormal distribution of phytopathogenic bacteria in corn, cowpea, tomato and watermelon seeds. American Phytopathological Society. 94:S34.
Technical Abstract: Numbers of colony-forming units (CFU) of Xanthomonas axonopodis pv. vignicola, Clavibacter michiganensis subsp. michiganensis and Acidovorax avenae subsp. citrulli were counted on MXP, CNS, and WFB 68 semi-selective media, respectively, from single seeds of cowpea (Vigna unguiculata), tomato (Lycopersicon esculentum) and watermelon (Citrullus lanatus) washed in phosphate-buffered saline (1 seed ml-1). Bacterial populations ranged from10 CFU seed-1 to 1.3 x 106 CFU seed-1. Cumulative probability plots of CFU seed-1 produced substantial curves with raw data, but a log-transformation demonstrated a linear relationship. Evidence of bacteria distributed lognormally also was obtained from ELISA assays for Pantoea stewartii subsp. stewartii by comparing absorbance values obtained from individual corn (Zea mays) seed to standard curves created from a P.s. stewartii dilution series. A lognormal distribution of bacteria in infected seeds has implications for determining sample sizes for seed health testing.