Building Mildew Mistakes
Mold in buildings is Often Mistaken for Mildew - a plant fungus

Mildew mistakes: this article discusses how to recognize building mold and how to know that indoors, it's not mildew.

We include photographs of a variety of white and green mold growths on clothing, leather, artworks, baskets and building surfaces - all examples of light colored molds that are not mildew (and that are potentially more harmful).

This article describes building mold (black mold, green mold, yellow mold, gray mold, and white mold) that is often mistaken for mildew.

Photographs of Mold Found on or In buildings, Building Contents, Clothing, Baskets, & Artworks: Molds that are Sometimes Mistaken for Mildew

Our photo (left) of white mold on a leather jacket illustrates a fungus that might be mistakenly called "mildew".

Here are photographs of mold on building exteriors, interiors, or building contents.

At this website, other photos of mold on indoor building surfaces may help you recognize mold in buildings, recognize probably-cosmetic mold, and recognize stuff that is not mold and does not need to be tested.

More photographs of mold that is often mistaken for or mis-named "mildew" are included in this article and links provide articles that correctly identify mildew as well as explain the difference between mildew and mold.

For teaching the distinction between the broad family of mold and its little subordinate clan of mildew, I owe a special thankyou to Dr. J.H., a New York mycologist who is not only far more educated than I (DF) about mold, mildew, and the world of fungi, but who also is a gentle and generous man.

When in my enthusiasm I showed J.H., light green "mildew" samples I'd collected from leather shoes in the closet of a very moldy home I'd inspected, J. asked gently: "Are you sure you want to call that 'mildew'?" He went on to explain that

Mildew, a sub-class of molds, is an obligate parasite that grows only on living plants, and is generally white in appearance.

At MILDEW PHOTOGRAPHS we illustrate the two mildew groups:

1. Oidium-Erysiphe, familiarly named Powdery Mildew, and
2. Peronosporaceae, familiarly named Downy Mildew

Often an inexperienced mold inspector, home inspector, or consumer may refer to these molds incorrectly as "mildew", either out of lack of technical expertise or out of an accurate belief that many people around real estate transactions are much less frightened by "mildew" than by "mold".

There are very many mold genera or species that can grow on a remarkably wide range of organic materials that are found both outdoors and inside, and that can appear in an wide range of colors (black, brown, red, green, gray, white, orange, tan, yellow, for example) and textures. A popular subset of about 200 of those are often found inside buildings on building contents or materials. Those are not likely to be mildew - unless you're looking at plants indoors.

Our page top photograph a severe basement mold contamination in a flooded home found in Poughkeepsie, New York.

Carpet mildew diagnosis: carpeting that has light mold or smells like mold might be described by an inexperienced inspector or a building owner as mildewed carpeting.

If your carpeting smells like "mildew" or "mold" it 's probably moldy whether you can see the mold or not by simple visual inspection.

See CARPET MOLD / ODOR TESTS for details.

Our photo of moldy carpet (left) was taken from a sample of carpeting that was the final target of a building mildew odor diagnosis procedure.

Carpet odors: carpeting that smells can be caused by a wide range of problems.

See ODORS GASES SMELLS, DIAGNOSIS & CURE

Carpet stains: can also be caused by a wide range of sources, some of which are harmless, others may diagnose other building problems such as a heating system that is not working properly, or building air leaks.

See CARPET STAIN DIAGNOSIS.

Mold on works of art: We define "mildew" stains on or in paint at MILDEW IN / ON PAINT.

In support of museum conservators we have also identified mold growth on as well as in paint in works of art. Mildew is not found on art works.

Our photograph of a painting being examined for contaminants was provided courtesy of museum conservator Ulrik Runeberg, Puerto Rico Art Museum during a joint forensic investigation.

Mold on painted building surfaces or furnishings: We define "mildew" stains on or in paint at Mildew in paint. Look closely at our peeling paint photograph at above left and you can see some black mold on the back surface of an old layer of exterior paint exposed by our peel-back of blistered paint on a wood clapboard wall. More black mold is visible on the exposed wood surface too.

Our micro-photograph of a cross-section cut moldy paint (below right) shows black mold growth inside the layer of paint sampled from a surface. It's mold, not mildew.

Our high-resolution microscope photograph (below) of mold found on exterior wall paint confirms that this is a mitosporic fungi, not mildew.

...

A closeup microscopic photo of mold found on building wall paint is shown here.

Our high-resolution microscope photograph (above) of mold found on exterior wall paint confirms that this is a mitosporic fungi, not mildew.

Mold or algae on roofs: We discuss stains mistaken for mildew on building roofs

at Catalog of BLACK ROOF STAINS

Mold on a Leather Jacket or on Clothing

In our forensic lab we confirmed that this "mildewed" leather jacket was actually contaminated with Aspergillus versicolor - it was moldy, not mildewed even though the owner naturally used that term to describe the odor.

Clothing that smells like "mildew" is moldy and can usually be restored by laundering or dry-cleaning. Leather garments need to be cleaned by a leather cleaning professional.

Mold on a Woven Laundry Basket

This "mildewed" laundry basket found in Mexico was mold-contaminated but although the basket was made of plant material, this black mold was not mildew. (Samples are on hand for further laboratory analysis.)

Interestingly the mold grew only on the basket fiber interior surfaces - a side of the plant material that was exposed after the basket reed material was first hand-split for weaving. The harder exterior surface of this bamboo-like plant material did not show much mold growth.

Even using bleach solution (plastic bowl at upper left) we were unable to successfully clean this moldy laundry basket - it was passed on to the trash truck along with other building basura.

Green "Mildew" Reported on Basement Ceiling

This green "mildew" on basement surfaces was confirmed to be mostly Aspergillus sp. mold.

The white, gray, and green "mildew" found on the underside of this building subflooring and on the floor joists was confirmed in our forensic laboratory as not "basement mildew" but rather a mixture of mostly Aspergillus sp. and some Penicillium sp. molds.

We also often find Trichoderma sp. (another green mold) on wooden subfloors and framing over wet or damp basements or crawl spaces.

Green and gray molds on building surfaces are often mistaken for mildew.

White mold in buildings that is not mildew is very common, found for example on wood surfaces, both painted and raw wood. Our photograph (left) shows white mold on an interior basement door.

Often we find white or light gray Aspergillus sp. or Penicillium sp. molds on these surfaces, but there are numerous other light colored or white indoor molds that may be present.

White Stuff that is Niether Mildew nor Mold

Other examples of white mold found in buildings that is often mistakenly called "mildew" can be seen

at WHITE MOLD PHOTOS.

White stuff that is not mold is also not mildew: Beware: many people mistake mineral salts or efflorescence for white mold or mildew.

Efflorescence is a white crystalline salt left on masonry surfaces where water or moisture have been evaporating.

.In general, mold is a term encompassing a very wide family of organisms (the Fifth Kingdom) that includes more than a million and a half species. Lots of molds grow on lots of different organic substances, under a variety of conditions of light and temperature, but all molds require moisture and something organic on which to grow (paper, wood, paint, cloth, leather, plastic, etc.).

Are There Colored Mildews? Pink Mildew?

On 2019-01-10 by Amy Reineri - my books and vinyl and other stuff are covered in mildew

Mildew only needs moisture or humidity to develop. In humid regions, mildew spores are everywhere and can grow on - literally - anything: ceramics, stone countertops, plastic laminate, vinyl siding, etc. They only need moisture, not "living plants" as your article states.

You may be mistakenly thinking of "powdery mildew" which is a plant problem, but the pink/salmon-colored mildew grows everywhere and on everything with enough warmth and humidity present - humidity or water is the key ingredient. It has a distinctive sour smell to it.

This Q&A were posted originally

at BOOK / DOCUMENT MOLD & WATER DAMAGE RESTORATION

On 2019-01-10 by (mod) - speaking properly, NO. Breadth of usage of the term "mildew" to refer to fungi vs. its "more proper" usage

Amy thank you for your comment.

Are you sure it's a proper "mildew" on your books and not some other mold genera/species that some people might loosely call "mildew"? Perhaps a pink or reddish yeast fungus or even an Aspergillus or a yeast fungus?

Confusion about what should be called "mildew" has been around since I was in knee pants, maybe longer. (Yarwood 1957)

The mildew sub-group of molds (it is argued that mildew is not a true mold) includes itself two families: Oidium-Erysiphe (powdery mildew) or "true mildew" and Peronosporacae (downy mildew) or "false mildew".

But in both cases, these grow only on living plants. Of course once a plant is diseased the sick portion of the plant may be other colors, often gray or brown. - (Bouzid 2008)

And I acknowledge that plenty of people use the word "mildew" widely when it'd be more-accurate to call their fungus "mold". Who cares? Well proper identification of a mildew or other fungus can be essential in choosing its method of control and key understanding its potential effects on plants, humans, or other animals or on other materials.

I believe that speaking properly or perhaps a bit strictly using current terminology, mildews are oblilgate parasites - found only on living plants - and are in the two groups I cite below, Erysiphales Powdery mildews and Peronosporacae Downy Mildews. An easy-to-use authority is Dictionary of the Fungi, from which I quote this definition of mildew:

Definition of mildew

(1) a plant disease in which the pathogen is seen as a growth on the surface of the host.

A powdery ('true') mildew is caused by one of the Erysiphaceae (e.g. the American (Sphaerotheca mors-uvae) and European - (Microphaera grossulariae) of Ribes);

a downy ('false') mildew is by one of the the Peronosporaceae (the first may be controlled by sulphur, the second by copper fungicides);

a dark mildew, or black mildew, by one of the Meliodales or Capnodiaceae;

(2) the staining, and frequently the breaking up, of cloth and fibres, paint, etc., by fungi and bacgteria (cf. mould);

(3) a fungus causing (1) or (2) (Kirk 2008)

Taxonomy of the Powdery mildews - "true" mildews - Erysiphales

Taxonomy of Powdery Mildew: Kingdom Eumycota, Phylum: Dikaryomycota, subphylum Ascomycotina, order Erysiphales (contains 28 genera, 100 species)

All of the members of this order are obligate parasites on leaves and fruits of higher plants, causing diseases called powdery mildews. (Kendrick 2017)

• Braun, U., R. T. A. Cook, A. J. Inman, and H. D. Shin. "The taxonomy of the powdery mildew fungi." The powdery mildews: a comprehensive treatise (2002): 13-55.
• Braun, Uwe. The powdery mildews (Erysiphales) of Europe. VEB Gustav Fischer Verlag, 1995.
• Jones, Hannah, John M. Whipps, and Sarah Jane Gurr. "The tomato powdery mildew fungus Oidium neolycopersici." Molecular Plant Pathology 2, no. 6 (2001): 303-309.
• Moseman, John G. "Genetics of powdery mildews." Annual Review of Phytopathology 4, no. 1 (1966): 269-288.
• Yarwood, Cecil E. "Powdery mildews." The Botanical Review 23, no. 4 (1957): 235-301.
  
  Introduction excerpt:
  
  Powdery mildews (Erysiphacaea) are a clearly defined family of obligately parasitic ascomycetous fungi which grow principally on the foliage of angiosperms and cause damage on a wide varity of crops.
  ...
  The term "mildew", used alone, is an unfortunate one, since a great variety of fungi is sometimes called "mildews". Since 1886 (255) the term "powdery mildews" has been commony limited to the Erysiphaceae and the term "downy mildews" to the Peronospracae.
  
  Powdery mildews were recognized and named at least as early as 1753 by Linnaeus (263).

Taxonomy of the Downy Mildews - "false" mildews - Peronosporaceae

Taxonomy of Downy Mildews: Kingdom Chromista, Phylum Oomycota, order Peronosporales, family Peronosporacae, genera Peronospora, species - various

Numerous species of Peronosporacae are obligately parasitic on higher plants (Kendrik 2017) and belong to the genera Bremia, Peronospora, Plasmopara and Pseudoperonospora.

Common examples: Downy Mildew of grape Plasmopara viticola ( Plasmopara - Peronosporacae) and Blue Mould of Tobacco Peronospora tabacina (Peronospora - Peronosporacae)

• Francis, SHEILA M., and Grace M. Waterhouse. "List of Peronosporaceae reported from the British Isles." Transactions of the British Mycological Society 91, no. 1 (1988): 1-62.
• Nasraoui, Bouzid. MAIN FUNGAL DISEASES OF CEREALS AND LEGUMES IN TUNISIA [PDF] Centre de Publication Universitaire, Tunisia (2008): 186.
• Swingle, W. T. "Some Peronosporaceae in the herbarium of the Division of Vegetable Pathology." The Journal of Mycology (1892): 109-130.
• Thines, Marco, and Young-Joon Choi. "Evolution, diversity, and taxonomy of the Peronosporaceae, with focus on the genus Peronospora." Phytopathology 106, no. 1 (2015): 6-18.
  Abstract:
  
  Downy mildews are a notorious group of oomycete plant pathogens, causing high economic losses in various crops and ornamentals. The most species-rich genus of oomycetes is the genus Peronospora.
  
  This review provides a wide overview of these pathogens, ranging from macro- and micro-evolutionary patterns, their biodiversity and ecology to short overviews for the currently economically most important pathogens and potential emerging diseases.
  
  In this overview, the taxonomy of economically relevant species is also discussed, as the application of the correct names and species concepts is a prerequisite for effective quarantine regulations and phytosanitary measures.
• Thines, Marco, Hermann Voglmayr, and Markus Göker. "Taxonomy and phylogeny of the downy mildews (Peronosporaceae)." Oomycete Genetics and Genomics: Diversity, Interactions, and Research Tools. Weinheim: Wiley-VCH (2009): 47-75.
• Voglmayr, Hermann, and Johann Greilhuber. "Genome size determination in Peronosporales (Oomycota) by Feulgen image analysis." Fungal Genetics and Biology 25, no. 3 (1998): 181-195.
• SeeReferences or Citations for additional citations

If you are seeing red or pink mildew I think that perhaps you are seeing species of other molds.

References on the Confusion of Types of Mildews

• BLACK.M.\N, V. H. and WELSFORD, E . J. (1916). Studies in the physiology of parasitism. II. Infection by Botrvtis cinerea. Ann. Bot. 30, 389
• BOOK / DOCUMENT MOLD & WATER DAMAGE RESTORATION
• BOYLE, C. (1921). Studies in the physiology of parasitism. VI. Infection by Sclerotinia Liheiiiaiia. Ann. Bot. 35, 337
• Corner, E. J. H. "Observations on resistance to powdery mildews." [PDF] New Phytologist 34, no. 3 (1935): 180-200.
  Excerpt:
  
  mildew conidia will germinate on any plant up to the stage of penetration of the cellulose layer of the host cell and of formation of an infection papilla, but that except on susceptible varieties the penetration process is then killed before it can enter the cytoplasm or after it has formed a rudimentary haustorium
• Kendrick, Bryce. The Fifth Kingdom. Hackett Publishing, 2017. ISBN13: 9781585100224, [book for sale at Amazon]
• Kirk, P. M., P. F. Cannon, D. W. Minter, and J. A. Stalpers. "Dictionary of the fungi 10th edition." CAB International, Wallingford, UK (2008).
• SALMON, E. S. (1904). Cultural experiments with the barley mildew, Erysiphe graminis. Ann Mycol. 2, 70, 255. 307.
• Sedlářová, Michaela, Lucie Kubienova, Zuzana Drabkova Trojanova, Lenka Luhova, Aleš Lebeda, and Marek Petřivalský. "The role of nitric oxide in development and pathogenesis of biotrophic phytopathogens–downy and powdery mildews." In Advances in Botanical Research, vol. 77, pp. 263-283. Academic Press, 2016.
  
  Excerpt: ... iotrophic oomycetes (Peronosporales, Oomycetes, Chromalveolata), causative agents of downy mildews, are distinct from the true fungi in many features … to study plant biotrophic oomycete interactions from the field conditions to molecular level ...
• Stakman, E. C. "PLANT PATHOLOGIST'S MERRY-GO-ROUND: A Survey of the Never-Ending Battle Against Plant Diseases." Journal of Heredity 37, no. 9 (1946): 259-265.
  Excerpt:
  
  There are rots and blights, wilts and cankers, smuts and rusts, mildews and galls, spots and scabs, each attacking particular kinds of plants … And there are hundreds of kinds of mildews: rose mildew, lilac mildew, oak mildew, wheat mildew, clover mil- dew, and so on and on …
  

...

Continue reading at MILDEW REMOVAL & PREVENTION or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Mildew Articles

• MILDEW REMOVAL & PREVENTION
• MILDEW on BOOKS?
• MILDEW ERRORS, IT's MOLD
• MILDEW in or on PAINT
• MILDEW PHOTOGRAPHS
• PAPAYA WHITE GROWTH vs DISEASE
• MOISTURE CONTROL in BUILDINGS
• MOLD APPEARANCE - WHAT MOLD LOOKS LIKE
• MOLD ATLAS & PARTICLES INDEX
• WHITE MOLD PHOTOS

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