SummaryThe majority of isolates of Fusarium avenaceum caused dry rot on potato tubers: many were as pathogenic as F. coeruleum. Pathogenicity of F. avenaceum was not related to the plant species from which the isolates originated. Tubers of potato cv. Cara were more susceptible than those ofcvs Romano or Maris Piper. Temperature (5-15 'C) had no effect on lesion depth but lesions tended to be slightly wider at the lowest temperature. Two isolates (of 61) from wheat and white lupin had a moderate level of resistance to thiabendazole. The results are discussed in relation to the control of dry rot in stored potato tubers.