Experiments on direct isolation of Pythium spp. from Finnish sugar beet soils

Pythium spp. were successfully isolated directly from sugar beet soils by the method of Ricci et al. (1976). The isolates obtained were divided in to four groups on the basis of morphological and growth habit characters. The groups showed large differences in in vitro pathogenicity. The importance of some factors affecting the estimation of Pythium propagule density is studied and discussed