Powdery mildew
General Powdery mildew is a fungal disease that is caused by many different species of fungi such as Erysiphe, Podosphaera, Oïdium, Leveillula. Damage [...] through the stomata and there are more stomata on the underside of the leaf. On the upper side, yellow spots are noticeable. In case of a severe epidemic, the [...] rain often limits the epidemics and spore dispersal by rain is negligible, since spores explode when in contact with water for no more than a few hours