 The evolutionary dynamics of plant pathogens are complex and dynamic, as they must adapt to the ever-changing landscape of crops and resistant genes. Two pathotypes of the wheat pathogen Puxinia tritocina emerged in succession, each with different levels of aggressiveness. The more recent pathotype was found to be more aggressive than the older one, suggesting that the landscape may play a role in shaping the evolution of pathogen populations. This article was authored by Fountain, Cecilia, Meyer, Kevin J. G., Boexel, Ann Lees, and others.