SUMMARYThe effects of cultivar, virulence of isolates ofLeptosphaeria coniothyrium, cane maturation and wound healing were examined in a series of inoculation experiments carried out over a 3–yr period in three countries in an attempt to explain why cane blight has caused serious yield losses in machine‐harvested red raspberries in Europe, but not in the Pacific Northwest of America. Three isolates ofL. coniothyriumfrom Puyallup (USA), Dundee (UK) and Dossenheim (FRG) were pathogenic on the three test cultivars Willamette, Malling Jewel and Glen Isla in all the experiments. Isolates and cultivars differed for aggressiveness and susceptibility respectively but their ranking was dependent on the test conditions and the differences were small and unlikely to explain the differences in incidence and severity of cane blight in raspberry fields in Scotland and the Pacific Northwest. Conditions at Dossenheim were most favorable for lesion development. At all sites, canes inoculated in late summer produced shorter lesions than those inoculated earlier. A delay between wounding and inoculation produced shorter lesions than simultaneous wounding and inoculat