hree resistant varieties of winter OSR are selected together with a mixture of susceptible varieties in six field experiments in fields of low, moderate, high and very high infection levels. Plot-wise DNA analysis of soil are correlated with disease severity and yield. Bioassays are carried out for optimal infection. The presence of virulent isolates breaking reistance of Mendel are identified and determined by classical methods. The potential risk of oil radish as a catch crop is investigated.The goal is to provide an improved support and guidelines for sustainable winter OSR production.