Scientists studied a beneficial fungus called Trichoderma atroviride that kills crop-damaging pathogens. They discovered that the type and quality of nutrients available directly affects how aggressive this fungus becomes. When provided with better nutrients like glucose and ammonia, the fungus produces more powerful enzymes to attack and destroy its prey. Remarkably, this fungus can even tell the difference between different types of pathogens and adjusts its attack strategy accordingly, making it a promising candidate for environmentally-friendly crop protection.