Research on such classical diseases as apple scab and grape powdery mildew has been continuous and intensive throughout the last century. However, relatively few investigations have had a major impact upon how we approach controlling those diseases. An overall goal of my research has been to identify those areas of pathogen biology, ecology, and epidemiology that are poorly understood, and which severely constrain our ability to improve disease management programs. The research frequently spans disciplinary, institutional, and international boundaries, and has involved collaborations with horticulturists, food scientists, and entomologists from the other departments at Geneva, and in countries from Norway to Australia.