pps-200211-0119 ArticleInAPeriodical 2002 Plant Protection Science 38 11 648-651 DědičP. PtáčekJ. HoráčkováV. MatoušekV. ČeřovskáN. FiligarováM. Potato virus S (PVS): puzzling virus for potato breeders and seed producers In the framework of PVS eradication from breeding materials of Czech potato cultivars, the systematic research was devoted to: susceptibility of cultivars, occurrence of PVS in imported and domestic materials, and to maintenance of virus-free basic grades potatoes on breeding stations. In the field-exposure trials was proved high level of susceptibility of most cultivars to PVS and by contraries, gradualy increased proportion of maintained virus-free cultivars of foreign, as well as domestic origin. Nevertheless severe infestation still persist in some of them. The contemporary situation with maintenance of virus-free basic material in CR was demonstrated.