Variation of Virulence, in Terms of Quantitative Reproduction of Globodera Pallida Populations, From Europe and South America, in Relation To Resistance From Solanum Vernei and S. Tuberosum Ssp. Andigena Cpc 2802

Forty populations of Globodera pallida originating from either South America or field sites in Europe were tested for their reproductive ability on a susceptible potato cultivar and five genotypes with quantitative resistance from either Solanum vernei or S. tuberosum ssp. andigena CPC 2802 in a glasshouse pot experiment. The results showed that there was a wide and continuous range of virulence (85% to 4% reproduction) to all the resistant genotypes. This range was as broad within the European populations as within those from S. America. There was a significant host clone x nematode population interaction, largely accounted for by grouping the clones according to the source of resistance and the populations by their continent of origin. Populations from Europe were relatively more virulent on genotypes derived from S. vernei. In contrast, populations from S. America were relatively more virulent on genotypes derived from S. tuberosum ssp. andigena CPC 2802. Examination of the data from the European populations also showed a significant host x population interaction tending to separate British from mainland European populations.