DISTRIBUTION AND FREQUENCY OF OCCURRENCE OF POTATO CYST-NEMATODE PATHOTYPES IN NORTHERN-IRELAND

The distribution and frequency of occurrence of potato cyst nematodes, Globodera rostochiensis and G. pallida, were examined in Northern Ire land. Globodera rostochiensis (pathotype Ro1) was the most abundant sp ecies, while Pa1 and Pa3 pathotype reactions could be discerned within G. pallida. Unlike other parts of the UK, species proportions appear not to have changed over the last 20 years, probably as a result of th e legislative control currently practised combined with the limited us e of Ro1-resistant cultivars within the country. Differences in the ge ographical distributions of the three pathotypes were observed, and th ese are discussed in relation to original potato cyst nematode introdu ctions and subsequent agricultural practices.