Synchytrium endobioticum is a severe pathogen of potato causing wart disease. For this obligate fungus many pathotypes (races) exist, which are pathogenic or nonpathogenic to different cultivars of potato. To determine to which race an isolate belongs, two biological assays are used on a set of different potato cultivars: the Spieckermann and the Glynne-Lemmerzahl test. A differential set of cultivars has been recommended by EPPO (European Plant Protection Organization) for these tests. Drawbacks of these tests are that it can take up to several weeks to score the interaction and results are difficult to score and also often not conclusive. Therefore possibilities were investigated to look for molecular markers for race specificity. The project aimed to develop an appropriate Taqman PCR protocol to reliably distinguish pathotype 1 from other pathotypes of Synchytrium endobioticum. The objectives were: to develop a Taqman PCR technique with acceptable specificity and reproducibility to distinguish S. endobioticum pathotype 1(D1) from the ‘higher’ pathotypes and to identify S. endobioticum pathotypes in reference collections of winter spores collected from green or composted ware material throughout Europe.