The effects of cultivar, virulence of isolates, cane maturation and wound healing were examined in inoculation tests over 3 yr in 3 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 Americas. Isolates from Puyallup (USA), Dundee (UK) and Dossenheim (FRG) were pathogenic on the 3 test cultivars Willamette, Malling Jewel and Glen Isla. Isolates and cultivars differed in aggressiveness and susceptibility respectively but their ranking was dependent on the test conditions and the differences were small. Conditions at Dossenheim were most favourable 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 inoculation.