Downy mildew of rose
This is, in fact, the sporulation of the pathogens extruding from the stomata. In lettuce, the foot is infected first and this causes the plant to fall over [...] Inside the plant, the pathogens produce haustoria, small organs with which the pathogen can take up nutrients from the living plant cells. The pathogens [...] 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 leaf fluffy growth