downy mildew

downy mildew
1. Also called false mildew. any fungus of the family Peronosporaceae, causing many plant diseases and producing a white, downy mass of conidiophores, usually on the under surface of the leaves of the host plant.
2. Plant Pathol. a disease of plants, characterized by mildewed, distorted, and yellowed foliage, caused by any of several fungi of the family Peronosporaceae, as of the genera Peronospora and Phytophthora.
[1885-90]

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      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.

      Downy mildew can be avoided by rotating annual flowers and vegetables and by avoiding overwatering, overcrowding, and poorly drained soil. Other avoidance measures are growing resistant varieties, sowing disease-free seed, removing diseased parts and crop refuse, eliminating weeds, and maintaining balanced soil fertility. The application of copper, maneb, or zineb is effective against many downy mildews, but the amount of residue on vegetables must be considered.

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Universalium. 2010.

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  • downy mildew — ☆ downy mildew n. a disease of angiosperms characterized by the appearance of whitish or downy patches of fungus on the surfaces of plant parts, caused by various fungi (family Peronosporaceae) …   English World dictionary

  • Downy mildew — Example of Downy mildew (left) along with powdery mildew on a grape leaf Downy mildew refers to any of several types of oomycete microbes that are obligate parasites of plants. Downy mildews exclusively belong to Peronosporaceae. In commercial… …   Wikipedia

  • downy mildew — noun Date: 1886 1. any of various parasitic lower fungi (family Peronosporaceae) that produce whitish masses of sporangiophores or conidiophores on the undersurface of the leaves of the host 2. a plant disease caused by a downy mildew …   New Collegiate Dictionary

  • downy mildew — down′y mil′dew n. 1) fng any common fungus of the family Peronosporaceae, appearing on damp vegetable or animal matter as a white fuzzy mass of spores 2) ppa a disease of plants caused by growth of downy mildew on the undersurface of the leaves,… …   From formal English to slang

  • downy mildew — /daʊni ˈmɪldju/ (say downee mildyooh) noun fungi belonging to the family Peronosporaceae, all of which are obligate parasites of vascular plants, as Plasmopara viticola, downy mildew of grapes …   Australian-English dictionary

  • downy mildew — noun any of various fungi of the family Peronosporaceae parasitic on e.g. grapes and potatoes and melons • Syn: ↑false mildew • Hypernyms: ↑mildew • Hyponyms: ↑blue mold fungus, ↑Peronospora tabacina, ↑onion mildew, ↑ …   Useful english dictionary

  • downy mildew — false mildew a mildew of the family Peronosporaceae …   Medical dictionary

  • Mildew — Example of downy mildew (left) along with powdery mildew on a grape leaf …   Wikipedia

  • mildew — mildewy, adj. /mil dooh , dyooh /, n. 1. Plant Pathol. a disease of plants, characterized by a cottony, usually whitish coating on the surface of affected parts, caused by any of various fungi. 2. any of these fungi. Cf. downy mildew, powdery… …   Universalium

  • mildew — mil•dew [[t]ˈmɪlˌdu, ˌdyu[/t]] n. 1) ppa a disease of plants, characterized by a cottony, usu. whitish coating on the affected parts, caused by any of various fungi 2) fng any of these fungi, esp. downy mildew or powdery mildew 3) fng any similar …   From formal English to slang

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