Seasonal phenology of Amphorophora agathonica and impact of aphid transmitted viruses in ‘Meeker’ raspberries

Crumbly fruit disease symptoms are a serious problem for raspberry producers in northern Washington and British Columbia. These symptoms result from a complex of plant viruses, including  Raspberry bush dwarf virus (RBDV), Raspberry leaf mottle virus (RLMV), and Raspberry latent virus (RpLV). RBDV is a pollen-borne virus, while RLMV and RpLV are transmitted by the large raspberry aphid, Amphorophora agathonica. Effective management of aphid transmitted viruses requires thorough knowledge of aphid biology, as well as how each virus impacts fruit quality and plant vigor. Aphid population dynamics were monitored through leaf samples collected from commercial raspberry fields throughout the growing season. Aphid populations peaked at the end of June, with a second peak occuring near the end of August. To determine how plant virus combinations affected cane vigor and fruit quality, 'Meeker’ raspberry plants were graft-inoculated singly with RBDV, RLMV, RpLV, and all combinations of the viruses (RBDV+RLMV, RBDV+RpLV, RLMV+RpLV, & RBDV+RLMV+RpLV). The greatest reduction in fruit quality was seen in treatments with mixed infections (RBDV + RpLV + RLMV, RBDV + RpLV, & RLMV + RpLV). All viruses caused a decline in vigor, especially in the first growing season, highlighting the importance of planting healthy raspberry root stock.