Downy mildew

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 agriculture, they are a particular problem for growers of crucifers, grapes and vegetables that grow on vines. The prime example is Peronospora farinosa featured in NCBI-Taxonomy and HYP3.

Contents

Symptoms

The initial symptoms of downy mildew appear on leaves as light green to yellow spots.[1]

Plant specific mildews

Hop Downy Mildew (caused by Pseudoperonospora humuli) is specific to hops (Humulus lupulus). The disease is the single most devastating disease in Western United States hopyards, since the microbe thrives in moist climates. Infected young hop bines become stunted with thickened clusters of pale curled leaves. These spikes have a silvery upper surface, while the undersides of leaves become blackened with spores. These dwarfed spikes are called "basal spikes". 'Lateral' or 'terminal' spikes occur further up the vine. An entire hop crop could be devastated in only a few days.

Similarly, cucurbit downy mildew (caused by Pseudoperonospora cubensis) is specific to cucurbits (e.g., cantaloupe (Cucumis melo), cucumber (Cucumis sativus), pumpkin, squash, watermelon (Citrullus lanatus) and other members of the Cucurbitaceae/gourd family). The disease is one of the most important diseases of cucurbits worldwide.

See also

References

  1. ^ Schilder, Annemiek. Downy mildew - Plasmopara viticola. MSU Plant Pathology.

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Look at other dictionaries:

  • 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 — 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… …   Universalium

  • 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 …  

  • 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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