Downy mildew of rose
infection and sporulation is relatively low, in general between 10 and 20 °C. Late in the season new overwintering oospores are produced and buried in the soil [...] stems and fruits. They cause lesions on the upper leaf surface, bordered by the veins, which are first yellow and then turn brown. On the underside of the [...] which is first white and later turns grey-brown. This is, in fact, the sporulation of the pathogens extruding from the stomata. In lettuce, the foot is