Characterisation of the distribution of individual response times in bacterial infection of plants

SUMMARY The distribution of time of visible response to infection was followed after inoculation of Pseudomonas syringae pv. syringae onto the flowers of pear cv. Williams, Pseudomonas syringae pv. phaseolicola into the leaves of bean cvs Borlotto di Vigevano and Saluggia, Corynebacterium michiganense subsp. michiganense into the stem of tomato cvs Fiorentina and C 1402 and Agrobacterium sp. biovar 3 into the stem of sunflower cv. Egnazia at a dosage of either 0.5–32 times the median effective dose (ED50) or 1–64 ED50. The distribution contracted and the median response time decreased as the dose of inoculum was increased for each host-pathogen combination. Modified Weibull regressions with shape parameter 1< c < 2.5 gave a highly significant fit to the observed distributions of individual response times in all dose groups and host-pathogen combinations.