The fungus Zymoseptoria tritici causes Septoria tritici blotch, the most destructive fungal disease of wheat grown in temperate climates worldwide. This disease reduces wheat yields by 5-10% per year, causing harvest losses worth between three quarters and one and a half billion Euros in France, Germany and the UK alone, and with another billion euros being spent on chemical control of the fungus. Researchers from the University of Exeter achieved a major breakthrough in the understanding of molecular mechanisms underpinning the aggressiveness of this pathogen.