In the evolutionary arms race between fungal pathogens and their plant hosts, the maintenance of genetic variation in the fungus has been presumed to represent a tradeoff between the value of increased virulence (infectivity) or increased population size. However, the existence of this tradeoff and the nature of these costs have not been extensively studied. In the 14 March
Thrall and Burdon performed greenhouse studies to characterize virulence and resistance in six strains of the fungus