Abstract
The plasmodiophorid Polymyxa graminis transmits plant viruses to cereal crops such as wheat, rye, barley and triticale. Soil samples from different locations and cereal host plants were analyzed for the presence of P. graminis ribotypes I and II, and tested for the occurrence of soil-borne viruses. P. graminis sequences mainly from fields in Germany used for virus resistance trials, but also from a site each in Poland and Denmark were obtained and deposited in the European Nucleotide Archive. The interactions between the components of the pathogen complex - vector ribotype and virus - and the host are discussed.