Different responses of winter oilseed rape (WOSR) varieties to various growing locality conditions as well as to the intensity of technological inputs are known. Organic grower-need varieties provide sufficient yield even within extensive growing conditions. Ten commonly grown line varieties in the Czech Republic were tested using extensive organic growing technology. These varieties were evaluated for the occurrence of fungal diseases by ripening and seed yield. Some of OSR tested varieties proved to have higher resistance to fungal diseases as well as significantly higher seed yields. Higher resistance against Phoma lingam proved varieties Caracas, Ontario, Liprima, Cando and Manitoba. Higher resistance against Sclerotinia sclerotiorum proved varieties Ontario, Smart and Oponent. The highest yield within a two-year average was produced by the Caracas, Manitoba and Ontario varieties. These varieties are more likely to be recommended for practical organic growing
