Abstract

Six blackberry or hybrid berry cultivars and 19 raspberry cultivars were assessed for their infectibility with, and sensitivity to, graft-inoculation with 10 distinct viruses found infecting Rubus in the UK. Cultivars were grafted with each of 2 isolates of the pollen-borne raspberry bushy dwarf idaeovirus (RBDV), 5 aphid-borne viruses: black raspberry necrosis virus, raspberry leaf mottle virus(RLMV), raspberry leaf spot virus(RLSV), rubus yellow net badnavirus and raspberry vein chlorosis nucleorhabdovirus (RVCV); and isolates of the nematode-transmitted nepoviruses, arabis mosaic, raspberry ringspot, strawberry latent ringspot and tomato black ring. All tested cultivars were infectible with a resistance-breaking isolate of RBDV but only about half of that number with the Scottish type isolate of the virus. The raspberry cultivars Autumn Bliss, and occasionally Glen Garry and Glen Prosen, developed leaf yellowing symptoms following infection with RBDV, but none of the other infected cultivars showed obvious leaf symptoms when kept in a heated glasshouse during the growing season. All tested cultivars were infectible with each of the 4 viruses transmitted in nature by the aphid, Amphorophora idaei. Most were infected symptomlessly, but 7 cultivars developed severe leaf spotting symptoms due to infection with RLMV or RLSV. All but 1 of the raspberry cultivars were infectible with RVCV, which is transmitted in nature by the aphid Aphis idaei, and almost all infected plants developed leaf symptoms; only 1 of the hybrid berry or blackberry cultivars tested was infected with RVCV. In tests with the 4 nepoviruses, all tested cultivars, except Tummelberry, were infectible with at least 1 or more of these viruses. However, cultivars responded differently to challenge inoculation with different isolates of individual nepoviruses. Several cultivars developed chlorotic leaf mottling following infection with some nepovirus isolates. The implications of these results for virus control are discussed in the light of the changing pattern of virus and virus-vector incidence in the UK.