Useful resistance was found in cv. Latham but its effectiveness was affected by the growth stage reached at inoculation and by kind of inoculum used. It was effective when field-grown canes were inoculated in mid-Aug. but less so when inoculated in early July, and more effective against a spore inoculum than a mycelial one. Resistance was inherited as a dominant multigenic character, but there were interactions between parents and 2 very favourable combinations were found. Rubus pileatus, R. mesogaeus, R. coreanus and R. lasiocarpus showed resistance when inoculated in pot tests; F1 hybrids obtained by crossing them with raspberry were largely susceptible. The problems of using these resistance sources in breeding are discussed.