The pollen-borne raspberry bushy dwarf virus (RBDV) is controlled only by planting RBDV-resistant cultivars. A single dominant gene, Bu, confers immunity to common isolates of RBDV but not to a resistance-breaking strain (RBDV-RB). Strong resistance (possibly immunity) to RBDV-RB, was identified in cv. Haida and shown to be heritable but occurred only when gene Bu was present with a second resistance component whose inheritance is probably multigenic.
Growing raspberry cultivars immune from infection with nepoviruses offers a potentially effective and low cost alternative to chemical control of vector nematodes. However, field studies with raspberry cultivars immune from the Scottish type isolates of arabis mosaic and raspberry ringspot nepoviruses have shown the existence of resistance-breaking variants of these two viruses.
Raspberry cultivars containing genes for resistance to the aphid vector Amphorophora idaei are infected much less readily than non-resistant cultivars with A. idaei-transmitted viruses. Several genes for A. idaei resistance that occur in raspberry differ in ability to prevent colonisation by one or more of the four A. idaei biotypes recognized in the UK. Plants with these genes exhibited both antixenosis and antibiosis, and there were differences in the effectiveness of the same gene in different genetic backgrounds.
The feasibility of introducing these different forms of resistance into raspberry is discussed.