Abstract

Raspberry bushy dwarf idaeovirus (RBDV) is common in Rubus crops worldwide and is the cause of yellows disease, crumbly fruit and degeneration in vigour in some cultivars. Because it is pollen-borne, growing cultivars resistant to the virus is the only means of control. Whilst resistance to 'common' isolates of the virus is present in many red raspberry (Rubus idaeus) cultivars, virtually all cultivars are infectible with resistance-breaking isolates that are present and spreading in crops in Europe. More recent analysis of RBDV isolates worldwide, indicates that there are several variants of RBDV in nature which poses further problems for control. Transgenic resistance using RBDV genes or gene sequences may offer the only effective means of controlling this virus and its variants. Progress in the development of such resistance in model Nicotiana species is reported. Reversion disease (blackcurrant reversion associated virus) is the most important disease of commercial blackcurrant crops worldwide. Its causal agent, is transmitted by the eriophyid gall mite, Cecidophyopsis ribis, and is itself a serious pest of blackcurrant. Due to the withdrawal of currently used acaricides to control mites and hence reversion disease, producing blackcurrant germplasm containing resistance to the gall mite vector and/or the reversion agent offers the only long-term means of effective control of this pest and disease in crops. Results of field experiments conducted in Scotland and Finland to assess the usefulness of such resistance are reported.