The influence of severity of seed tubers infestation with black scurf was studied as related to potato plant growth, stem canker, yielding and incidence of black scurf on progeny tubers. Increasing levels of sclerotia on seed tubers caused worse plant emergence, increasing stem canker incidence and disease symptoms on stems, but their severity was dependent on weather conditions. Increasing of black scurf on mother tubers affected relatively the yield and tuber quality. The development of black scurf on progeny tubers was less dependend on seed tuber infestation with black scurf.