Scientists studied how two types of fungi interact when grown together in the laboratory. They found that different strains of Trichoderma fungi and beneficial mushroom fungi (Laccaria) communicate and compete using chemical signals that vary depending on how close they are to each other. When fungi are far apart, they use airborne chemicals, but when they touch directly, they change their chemical production dramatically. These findings could help improve the use of Trichoderma as biological pest control agents in agriculture.