Survey of winter wheat for soil-borne wheat mosaic virus (SBWMV), wheat spindle streak mosaic virus (WSSMV), their fungal vector Polymyxa graminis and other viruses in this disease complex. Analysis of the impact of the soil-borne virus complex on selected wheat cultivars. Characterization of any previously unrecorded viruses, with particular emphasis on specific responses of selected wheat cultivars and breeding stocks for disease resistance. Analysis of the host plant-virus-fungus interactions.