Past efforts and future perspectives of managing major diseases of red raspberries in British Columbia

British Columbia produces approximately 80% of Canada’s red raspberries. Several fungal and viral diseases are concerns for red raspberry production in the region. Among them, a root rot and wilting complex (attributed primarily to Phytophthora rubi) and pre- and post-harvest fruit rots (primarily caused by Botrytis cinerea) are the fungal diseases of greatest concern, while root lesion nematode (Partylenchus penetrans) is also associated with poor field performance and replant diseases. Raspberry mosaic disease (RMD), a complex of viruses vectored by the aphid Amphorophora agathonica, and Raspberry bushy dwarf virus (RBDV) are also of significant concern in the region. Over the years, the raspberry breeding program in BC has worked to identify and incorporate sources of host resistance for several major diseases into its germplasm, but has not consistently screened selections or seedling populations for disease reaction, instead relying on observation of unsprayed field plots to evaluate seedlings and selections. Aphid resistance has been the only consistent primary screen utilized through the breeding program’s history and, as a result, the program’s biggest success has been in breeding for aphid resistance to slow the spread of RMD, but this has been compromised in recent years by new resistance-breaking aphid biotypes. Progress has also been made with resistance to Phytophthora root rot, but has been slow for a variety of reasons. Future research is required to understand pathogen population dynamics (such as changes in pathogen strains) and infection periods targeting fungicide application timings and cultural controls for better disease management, as well as development of molecular tools to enable more efficient screening for host resistance in breeding populations