Response of UK winter wheat cultivars to <Emphasis Type="Italic">Soil-borne cereal mosaic</Emphasis> and <Emphasis Type="Italic">Wheat spindle streak mosaic viruses</Emphasis> across Europe.

Twenty-one UK winter wheat cultivars were grown over three seasons at sites with natural inoculum sources of Soil-borne cereal mosaic virus (SBCMV) and Wheat spindle streak mosaic virus (WSSMV) located in France, Italy and the UK. Plants were assessed visually for virus symptoms and leaf extracts were tested for the presence of each virus using enzyme-linked immunosorbent assays (ELISA). Cultivars showing little or no foliar symptoms and low levels of virus in leaf tissue were classified as resistant to each virus. All the trials were taken to harvest and agronomic data collected. At the most heavily infected sites, severe symptoms of SBCMV were observed in all UK cultivars except Aardvark, Charger, Claire, Cockpit, Hereward and Xi 19. The latter cultivars exhibited either light or no symptoms and little or no SBCMV infection in leaves. In fields with WSSMV, the virus failed to develop in Italy, but was detected in the leaves of all the susceptible control cultivars at a site in France. However, no UK cultivar tested positive for WSSMV. Multi-site analysis indicated that the presence of WSSMV did not increase the impact of SBCMV on the height, thousand-grain weight or yield of UK cultivars. The wheat cultivars on test gave a similar response to SBCMV across three European countries. Possible sources of SBCMV resistance are discussed.