And the nasty ones lose in the end: foliar pathogenicity trades off with asexual transmission in the Irish famine pathogen Phytophthora infestans.

A trade-off between pathogenicity and transmission is often postulated to explain the persistence of pathogens over time. If demonstrated, it would help to predict the evolution of pathogenicity across cropping seasons, and to develop sustainable control strategies from this prediction. Unfortunately, experimental demonstration of such trade-offs in agricultural plant pathogens remains elusive.

Long-distance gene flow outweighs a century of local selection and prevents local adaptation in the Irish famine pathogen Phytophthora infestans.

Sustainably managing plant resistance to epidemic pathogens implies controlling the genetic and demographic changes in pathogen populations faced with resistant hosts. Resistance management thus depends upon the dynamics of local adaptation, mainly driven by the balance between selection and gene flow. This dynamics is best investigated with populations from locally dominant hosts in islands with long histories of local selection.