Abstract
Four tomato cultivars with varying degrees of resistance to Pseudomonas solanacearum were inoculated with a culture of this organism containing 106 colony-forming units (CFU) mL-1 at different growth stages of the host plants. Bacterial colonization and multiplication in susceptible and resistant genotypes were studied. In the susceptible variety the incubation period for the development of wilt symptoms did not vary with the growth stage of the host plant, and the bacterial population grew with the increase in the duration of the post-inoculation period. However, in the tolerant cultivars, although colonization occurred, the bacterial population did not reach the critical level, i.e., 9 × 106 CFU mL-1, for wilting, and it remained constant or decreased.
