FIG. 2.

In infected host tissue, Ralstonia solanacearum populations declined rapidly following fluctuating temperature cycles of 48 h at 5°C and then 48 h at −10°C. Closed triangles represent the mean population sizes of R3bv2 strain UW551, and open squares represent endemic U.S. strain K60. Mean bacterial population sizes were measured by dilution plating: chopped stems of symptomatic R. solanacearum-inoculated geranium plants (A), chopped stems of wilting R. solanacearum-inoculated tomato plants (B), or cores of potato minitubers inoculated with ∼2 × 10⁹ CFU of the relevant R. solanacearum strain (C). Infected plant material was sampled after each 4-day temperature cycle. The experiment was repeated six times, with three technical replicates per biological replicate (A) or three times with three technical replicates per biological replicate (B, C). The dashed line represents the detection limit. Bars represent the standard errors of the means.