powdery mildew

powdery mildew
1. any of various parasitic fungi of the ascomycete order Erysiphales, which produce a powderlike film of mycelium on the surface of host plants.
2. Plant Pathol. a disease caused by powdery mildew, characterized by yellowing and death of the foliage and a white mealy growth of fungus on the surface of above-ground parts.
[1885-90, Amer.]

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      plant disease of worldwide occurrence, caused by many specialized races of fungal species in the genera Erysiphe, Microsphaera, Phyllactinia, Podosphaera, Sphaerotheca, and Uncinula. Hundreds of species of trees, shrubs, vines, flowers, vegetables, fruits, grasses, field crops, and weeds can be affected by powdery mildew.

      A superficial, white or light gray, powdery to felty growth of intertwined hyphae (fungus strands) forms on the surface of leaves, buds, young shoots, fruits, and even flowers. The white, powdery appearance is due to large numbers of microscopic spores (conidia) borne in chains. These wind-borne spores uniquely do not require free water for germination and infection. New crops of conidia can be produced every 3 to 14 days. If the disease is severe, the mildewed plant parts may be stunted and distorted. Leaves commonly turn yellow and wither, flowers are distorted or fewer in number, and fruit yield and quality are reduced. Mildew is most severe in crowded, shady, poorly aerated locations when nights are cool and days are warm. At maturity, or in the fall, round black specks, which are sexual fruiting bodies, or cleistothecia, may form in the mildew. In the spring the cleistothecia crack open to release one or more spore sacs (asei) containing ascospores that blow to nearby plant parts and initiate infection. Overwintering also occurs as mycelial mats on crops or weeds. Sulfur dust, lime sulfur, and dinocap (Karathane) are effective against many powdery mildews but should not be applied in hot weather.

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Universalium. 2010.

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  • Powdery mildew — is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of fungi in the order Erysiphales. It is one of the easier diseases to spot, as its symptoms are quite distinctive. Infected… …   Wikipedia

  • powdery mildew — Mildew Mil dew, n. [AS. melede[ a]w; akin to OHG. militou, G. mehlthau, mehltau; prob. orig. meaning, honeydew; cf. Goth. milip honey. See {Mellifluous}, and {Dew}.] (Bot.) A growth of minute powdery or webby fungi, whitish or of different colors …   The Collaborative International Dictionary of English

  • powdery mildew — ☆ powdery mildew n. 1. any of an order (Erysiphales) of ascomycetous fungi that are parasites on the surfaces of higher plants and produce closed fruiting bodies in a powdery mass 2. a plant disease caused by a powdery mildew …   English World dictionary

  • powdery mildew — noun Date: 1889 1. an ascomycetous fungus (family Erysiphaceae) producing abundant powdery conidia on the host 2. a plant disease caused by a powdery mildew …   New Collegiate Dictionary

  • powdery mildew — pow′dery mil′dew n. 1) fng any of various fungi of the ascomycete order Erysiphales that produce a powderlike film of mycelium on the surface of host plants 2) ppa the plant disease caused by powdery mildew • Etymology: 1885–90, amer …   From formal English to slang

  • Powdery mildew (barley) — Powdery mildew is a fungal disease of barley caused by Blumeria graminis f. sp. hordei . The disease has a worldwide distribution and is most damaging in cool, wet climates. The host range of the form species hordei is restricted to barley and… …   Wikipedia

  • powdery mildew — noun any of various fungi of the genus Erysiphe producing powdery conidia on the host surface • Hypernyms: ↑mildew • Member Holonyms: ↑Erysiphe, ↑genus Erysiphe …   Useful english dictionary

  • powdery mildew — a mildew of the order Erysiphales …   Medical dictionary

  • Mildew — Mil dew, n. [AS. melede[ a]w; akin to OHG. militou, G. mehlthau, mehltau; prob. orig. meaning, honeydew; cf. Goth. milip honey. See {Mellifluous}, and {Dew}.] (Bot.) A growth of minute powdery or webby fungi, whitish or of different colors, found …   The Collaborative International Dictionary of English

  • mildew — [mil′do͞o΄, mil′dyo͞o΄] n. [ME mildewe < OE meledeaw, nectar, lit., honeydew, akin to Goth milith, honey < IE base * melit (> L mel, Gr meli, honey) + base of OE deaw,DEW] 1. a thin, furry, usually whitish coating or discoloration,… …   English World dictionary

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