Mildew refers to certain kinds of mold
Molds are fungi that grow in the form of multicellular filaments called hyphae. Molds are not considered to be microbes but microscopic fungi that grow as single cells called yeasts...

s or fungi
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...


In Old English, it meant honeydew
Honeydew (secretion)
Honeydew is a sugar-rich sticky liquid, secreted by aphids and some scale insects as they feed on plant sap. When their mouthpart penetrates the phloem, the sugary, high-pressure liquid is forced out of the gut's terminal opening. Honeydew is particularly common as a secretion in the Hemipteran...

 (a substance secreted by aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...

s on leaves, formerly thought to distill from the air like dew
[Image:Dew on a flower.jpg|right|220px|thumb|Some dew on an iris in Sequoia National Park]]Dew is water in the form of droplets that appears on thin, exposed objects in the morning or evening...

), and later came to mean mildew in the modern sense of mold or fungus.

Plant pathogens

What horticulturalists and gardeners often refer to as mildew is more precisely called powdery mildew
Powdery mildew
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 plants display white powdery spots on the...

. It is caused by many different species of fungi
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

 in the order Erysiphales
Erysiphales are an order of ascomycete fungi. The order contains one family, Erysiphaceae. Many of them cause plant diseases called powdery mildew.-Systematics:The order contains one family , 28 genera and approximately 100 species...

. Most species are specific to a narrow range of hosts, and all are obligate parasite
Obligate parasite
An obligate parasite is a parasitic organism that cannot complete its life cycle without dependence on its host.-See also:*Obligate intracellular parasite*Parasitism*Parasitic plant*Facultative parasite...

s of flowering plants. The species that affects roses is Sphaerotheca
Sphaerotheca (fungi)
Sphaerotheca is a genus of ascomycete fungi that currently includes two plant pathogen species, Sphaerotheca epilobii and Sphaerotheca castagnei, that cause forms of Powdery mildew. The original type species, Sphaerotheca pannosa, now belongs to the genus Podosphaera....

 pannosa var. rosa

Another plant-associated type of mildew is downy mildew
Downy mildew
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...

. Downy mildews are caused by fungus-like organisms in the family Peronosporaceae
Peronosporaceae are a family of water moulds that contains 17 genera, comprising more than 600 species. Most of them are called downy mildews. The closest relative of Peronosporaceae is Phytophthora....

 (Oomycota). They are obligate plant pathogens, and the many species are each parasitic on a narrow range of hosts. In agriculture, downy mildews are a particular problem for growers of potatoes, grapes, tobacco and cucurbits.

Household Varieties

The term mildew is often used generically to refer to mold growth
Mold growth, assessment, and remediation
Mold assessment and mold remediation are techniques used in occupational health: mold assessment is the process of identifying the location and extent of the mold hazard in a structure, and mold remediation is the process of removal and/or cleanup of mold from an indoor environment.-Health...

, usually with a flat growth habit. Molds can thrive on many organic materials, including clothing, leather, paper, and the ceilings, walls and floors of homes or offices with poor moisture control. There are many species of molds. The black mold (often called mildew) which lives on shower walls, window sills, and other places where moisture levels are high is often Stachybotrys chartarum
Stachybotrys chartarum
Stachybotrys chartarum, also called Stachybotrys atra, Stachybotrys alternans or Stilbospora chartarum, is a black mold that produces its conidia in slime heads. It is sometimes found in soil and grain, but mostly isolated from cellulose-rich building materials in damp or water-damaged buildings. S...

 and is linked with sick building syndrome
Sick building syndrome
Sick building syndrome is a combination of ailments associated with an individual's place of work or residence. A 1984 World Health Organization report into the syndrome suggested up to 30% of new and remodeled buildings worldwide may be linked to symptoms of SBS...

. In unaired places, such as basements, they can produce a strong musty odor.

The English
English language
English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...

 word was exported into French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

 as mildiou and as mildiu in Spanish
Spanish language
Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...


External links

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