Powdery mildew background Powdery mildew (Leveillula taurica) is most prevalent in warm, dry atmosphere. The optimum germinating temperature is approximately 25°C with humidity ranging between 50 – 75%. It is quite common for inexperienced growers to identify powdery mildew as downy mildew. The most important differences are powdery mildew are found in summer and on [...]