An International Scheme for Identifying and Classifying Pathotypes of Potato Cyst-Nematodes Globodera Rostochiensis and G. Pallida

Following joint tests in the Netherlands, Germany and the United Kingdom a new scheme is proposed for naming pathotypes of potato cyst-nematodes. Pathotypes of Globodera ( = Heterodera) rostochiensis and G. pallida are designated separately using a simple nomenclature Ro1 to Ron for G. rostochiensis and Pa1 to Pan for G. pallida. Currently seven clones are used to differentiate five pathotypes of G. rostochiensis and three of G. pallida. Several of the pathotypes recognised in the British, Dutch and German National Schemes are the same. Results of pathotyping tests may show considerable variation; adequate replication and standardisation of method are essential. With an internationally used scheme it is highly desirable that new pathotypes or differential clones are added only after testing at Institutes in several countries.