What are the symptoms of downy mildew in rapeseed?

(Agricultural Wealth Network) The pathogen can infect leaves, stems, flowers, pedicels, siliques and other parts. After the leaves are infected, pale yellow spots first appear; as the lesions expand, they are restricted by the leaf veins and form irregular yellow-brown patches, and on the underside of the leaves the lesions bear a frosty mold layer, which consists of the pathogen's sporangia and sporangiophores; in severe cases the entire leaf turns brown and dies. After the stems, bolting stems, branches and pedicels are infected, chlorotic spots first appear on the diseased parts, and later the lesions expand into irregular yellow-brown patches, also bearing a layer of downy mildew-like material just like the leaves. After the pedicels become diseased, they are often swollen and deformed, and the floral organs enlarge and turn green in a dragon-head shape, with a smooth surface on which a frosty mold layer also appears. When the whole plant is severely affected, the entire plant is covered with mold, turns brown and dies.