The effect of continuous rearing of a population of Globodera pallida (Pa 2) on susceptible or partially resistant potatoes

A population of the white potato cyst nematode, Globodera pallida , (pathotype Pa 2) was reared for 5 years, in outdoor plots in eastern Scotland, on one susceptible and two partially resistant hybrids bred from Solanum vernei. No selection for increased multiplication rate was apparent. Results of a glasshouse pot test after 5 years showed that selection for a small but significant increase in nematode fecundity had occurred in a population produced for five generations on a clone which was 90% resistant.