AbstractIsolates ofErwinia carotovorasub sp.atroseptica, E. carotovorasub sp.carotovoraandE. chrysanthemiwere compared for their ability to rot potato tubers and to elicit the accumulation of phytoalexins. With three incubation temperatures (15, 22 and 30°C) tubers were more susceptible at higher temperatures and mean rot weights were inversely correlated with mean rishitin concentrations. However, within treatment variation between tubers in the extent of rotting was not correlated with rishitin concentration suggesting that other factor(s) also affect resistance. Phytoalexins, including 15‐dihydrolubimin, 3‐hydroxylubimin, phytuberin and solavetivone, were measured by high pressure liquid chromatography using a silica co