A molecular probe, p3POT, was constructed of PSTVd, PVY, PLRV cDNA fragments introduced into pUCl8 vector. Sequencing of the inserts revealed that cloned fragments covered conservative parts of pathogenic genomes. Dot-blot hybridization of digoxigenin-labelled construct to crude extracts from plants infected with different potato viruses proved high sensitivity and specificity of the p3POT probe. This makes p3POT probe an useful tool for the routine testing, and selection of virus-free potatoes