downy mildew

n.1. Any of various plant diseases caused by oomycetes and characterized by whitish gray patches of spores on the lower surfaces of leaves.2. An oomycete causing such a disease.

downy mildew

n 1. (Plant Pathology) a serious plant disease, characterized by yellowish patches on the undersurface of the leaves, caused by the parasitic fungi of the family Peronosporaceae, such as Peronospora destructor: affects onions, cauliflower, lettuce, etc 2. (Plant Pathology) any of the fungi causing this disease

down′y mil′dew

n. 1. any common fungus of the family Peronosporaceae, appearing on damp vegetable or animal matter as a white fuzzy mass of spores. 2. a disease of plants caused by growth of downy mildew on the undersurface of the leaves, characterized by crumpling, yellowing, and death of the foliage. [1885–90]

Thesaurus

Noun

downy mildew - any of various fungi of the family Peronosporaceae parasitic on e.g. grapes and potatoes and melonsfalse mildewfamily Peronosporaceae, Peronosporaceae - parasitic fungi: downy mildewsblue mold fungus, Peronospora tabacina - fungus causing a serious disease in tobacco plants characterized by bluish-grey mildew on undersides of leavesonion mildew, Peronospora destructor - fungus causing a downy mildew on onionsPeronospora hyoscyami, tobacco mildew - fungus causing a downy mildew on growing tobaccomildew - a fungus that produces a superficial (usually white) growth on organic matter

Downy Mildew

downy mildew

[¦dau̇n·ē ′mil·dü] (plant pathology) A fungus disease of higher plants caused by members of the family Peronosporaceae and characterized by a white, downy growth on the diseased plant parts.

Downy Mildew

a dangerous plant disease caused by parasitic fungi of the class Phycomycetes of the family Perono-sporaceae. It attacks the green parts of the plant, primarily the leaves. Spots form on the diseased parts of the plant; the lower portions of the spots are covered with a whitish, grayish, or violet film, which is the sporangiosphore of the fungus (zoosporangia with sporangiosphores). Zoosporangia may appear repeatedly during the growing season; disseminated in the air, they are the principal source of infection. High humidity and soil with high moisture content foster the development of downy mildew. In most of the causative agents, the mycelium lives one year, dying along with the affected parts of the plant. However, sometimes it is perennial, surviving in bulbs, roots, and other wintering organs. All species of the family Peronosporaceae are obligate parasites, extremely specialized in their nutrition (requiring a specific host). The most injurious downy mildews are those that infect grapes, cabbages, turnips, onions, alfalfa, cucumbers, sunflowers, beets, tobacco, and several other cultivated plants.

Control measures include the implementation of correct cultivation procedures, the selection of resistant varieties, and dusting or spraying the plants with fungicides.

P. N. GOLOVIN

downy mildew

Related to downy mildew: powdery mildew, damping off

noun

Synonyms for downy mildew

noun any of various fungi of the family Peronosporaceae parasitic on e

Synonyms

false mildew

Related Words

family Peronosporaceae
Peronosporaceae
blue mold fungus
Peronospora tabacina
onion mildew
Peronospora destructor
Peronospora hyoscyami
tobacco mildew
mildew