Downy Mildew

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Related to Downy Mildew: powdery mildew, damping off

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.


References in periodicals archive ?
Geneticists and breeders have, to date, identified multiple sources of resistance to powdery mildew, downy mildew and phomopsis.
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The diseases such as powdery mildew, Downy mildew are tested by proposed algorithm.
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Models for quantifying the damage caused by downy mildew can be obtained by quantifying severity of the disease and correlating it with yield.
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Ozone will not work for other fungal diseases such as downy mildew, black rot, and bitter rot--which are prevalent in humid climates--because those infections occur within the plant tissue.
Downy mildew is usually a lettuce grower's worst nightmare; it's the biggest problem in lettuce production.
Pathogen isolates were sampled from naturally infected plants in sunflower parcels at Clermont-Ferrand by the Plant Protection Service during its annual downy mildew survey.
Investigations of alfalfa resistance to fungal diseases showed that material of different origin were considerably different by resistance to downy mildew (Jie et al.
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