downy mildew
downy mildew
1885–90
Based on the Random House Dictionary, © Random House, Inc. 2012.
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| an extraordinary or unusual thing, person, or event; an exceptional example or instance. |
| a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison. |
| downy mildew | |
| —n | |
| 1. | 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. | any of the fungi causing this disease |
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downy mildew  (dou'nē) Pronunciation Key
A disease of plants caused by oomycete organisms of the order Peronosporales and characterized by gray, velvety patches of spores on the lower surfaces of leaves. Downy mildew of the grapevine nearly destroyed the french wine industry in the 1870s, spurring the development of the first chemical pesticides used on plants. |
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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downy mildew
disease of plants, especially in cool humid regions, caused by several fungi, including species of Basidiophora, Bremia, Peronospora, Phytophthora, Plasmopara, Pseudoperonospora, and Sclerospora. White, gray, bluish, or violet downy patches of mildew form mostly on the undersides of leaves in damp weather. Pale-green to yellow or brown areas usually develop on the upper leaf surface opposite the downy growth. Affected leaves often wilt, wither, and die early. Stems, flowers, and fruits are sometimes infected. Seedlings may wilt and collapse. Garden plants, bush fruits, vegetables, and certain trees, shrubs, field crops, and weeds are susceptible.
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