This research shows that Trichoderma hypoxylon, a beneficial fungus used in agriculture, produces different versions of antifungal compounds called epidithiodiketopiperazines (ETPs) to fight various harmful fungi. By deleting genes responsible for modifying these compounds, scientists found that different modifications work better against different pathogens—some modifications are more effective against mold fungi while others work better against grain pathogens. This demonstrates that the fungus uses chemical diversity as a strategy to protect crops from multiple threats.