Downy mildew of rose
brown. On the underside of the leaf fluffy growth appears which is first white and later turns grey-brown. This is, in fact, the sporulation of the pathogens [...] For most downy mildews, the optimum temperature is around 15 °C. The closer the temperature is to these 15 °C , the shorter the leaf wetness period that [...] Inside the plant, the pathogens produce haustoria, small organs with which the pathogen can take up nutrients from the living plant cells. The pathogens