Effects of growing resistant potatoes with gene H1 from Solarium tuberosum ssp. andigena on populations of Heterodera rostochiensis British pathotype A

Pure pathotype A populations of Heterodera rostochiensis produce a few females on ex andigena hybrids with the H₁ gene for resistance. As the proportion of larvae able to become female on ex andigena hybrids was not increased by reproducing the nematodes on such hybrids for 3 years, these females seem not to be genetically different from the rest of the population. The proportion increased rapidly when the initial population contained a few pathotype (species) E nematodes but again no increase in the proportion of pathotype (species) A larvae able to become female on ex andigena was detected and pathotype E replaced pathotype A.