Occurrence of a white touch on leaves and stalks of a cucumber a sign at one of fungoid illnesses of a cucumber - mealy dew. It develops in July-August, affects also a water-melon, a melon. To warn development of mealy dew, it is necessary to plough the vegetative rests deeply. Early kinds of a cucumber suffer from illness less.
In the south false mealy dew (peronosphoroz) is extended. Disease signs - on the top surface of leaves are visible brown -yellow stains, on bottom - a grayish-violet film. Merging, stains cover all surfaces of leaves, the leaves become fragile.