Difference Between Black Mold and Mildew

The key Difference Between Black Mold and Mildew is in their appearance. The black mold takes up a fuzzy appearance whereas mildews are flat colony units. Black molds are green or black in color while mildew is gray or white in color.

Fungi belong to the domain Eukarya and are found in many terrestrial and aquatic environments. Filamentous fungi that are found in terrestrial environments in both moist and dry conditions can be classified into two main categories. They are Black Molds and Mildews.

Molds also known as Stachybotrys, usually show a greenish black growth and found in both indoor and outdoor environments. Black molds take up a fuzzy appearance, and it penetrates through the surface. Mildews are two main types such as Downy mildew and Powdery mildew. They are more flat colonies and can be easily removed from the surface due to its structure.

What is a Black Mold?

Black mold is a type of fungi. Black mold is termed as such due to the greenish black appearance it bears. Molds grow both indoor and outdoor and on foods such as bread.

In indoors, it grows in slightly moist places where there are water leakages or on moist walls. In outdoors, it can grow in plant pots, water lines or near wells. The most common types of molds include species belonging to Cladosporium, Penicillium, Aspergillus, and Alternaria, all of which are spore-forming fungi. The spreading of black molds takes place via spores which are dispersed through the wind.

Prolonged spreading of black molds owing to humid conditions and moist conditions can lead to skin irritations, respiratory problems, eye irritations, asthma and allergic responses. The spread of black mold also results in bad odor.

Immuno-compromised individuals may contact severe allergic responses with relation to asthma and chronic lung diseases. Period of exposure is an important factor which leads to clinical manifestations resulting from black molds.

It is important to disinfect the places where there is black mold growth using appropriate antifungal agents or fungicides. It is important to take proper advice on disinfection as certain fungicides could enhance the spread of the black molds instead of inhibiting their spread.

When building houses and buildings, special care should be taken to balance the moisture content in the indoor environment by installing proper water lines. It is always recommended to use air conditioners to avoid the spread of the black molds.

Difference Between Black Mold and Mildew

Figure 01: Black Mold Spread on Walls

If a person is infected with a black mold, it is advised to test the sample of black mold to identify the species of that particular fungus for proper medication. Testing can be done through simple staining techniques in a laboratory.

Antifungal treatment can be administered. Extreme toxicity levels should be addressed promptly, and the place should be evacuated fast.


What is a Mildew?

Mildew is a type of fungi which is white or grey in color and appears as flat spreads on surfaces of moist areas. They are easy to be removed in comparison to molds. There are two main types of Mildews. They are Powdery mildew and Downy mildew.

Powdery Mildew

Powdery Mildew belongs to the family of Erysiphaceae. They are mostly considered as plant pathogens growing on both sides of leaves and shoots of beans, lettuce, fruit trees, and grasses.

They produce a powdery spore and hence referred to as Powdery mildew. Powdery mildew uses the moisture present on the leaf surfaces for its survival and propagation. They require relatively high humidity, medium levels of sunlight and temperature for its growth.

Downy Mildew

The other type of mildew which is Downy mildew belongs to the fungal family Peronosporaceae. This type of mildew appears as yellow spots on the top edges of leaves, and they require high moist conditions for its growth.

They affect crops such as strawberries, cabbage, beets, and lettuce. Downy mildew is primarily observed on the underside of the leaves and prefers low temperatures and high moist conditions for growth.

Key Difference Between Black Mold and Mildew

Figure 02: Downy Mildew and Powdery Mildew

Mildews can be controlled mainly by spraying fungicides on crops, and the infected plant parts should be removed off and cleared from the field as soon as it is detected.

Spreading of spores is the main manner in which the plant disease is spread. Therefore, when planting and constructing the field, elevation and the direction of the wind should be well analyzed.

What are the Similarities Between Black Mold and Mildew?

  • Both are types of fungi which are filamentous.
  • Both form spores.
  • Both fungi prefer moist warm environments.
  • Both spread its spores by the wind.
  • Both are found in terrestrial environments.
  • Both can be removed by using suitable fungicides and antifungal
  • Both can lead to toxicity causing allergic responses.

What is the Difference Between Black Mold and Mildew?


Black Mold vs Mildew

Mold is a type of fungi which appears as black or green colors in both indoor and outdoor environments. Mildew is another type of fungi which appears as gray or white colonies in growing plants.
Molds are mainly distributed in moist indoor and outdoor environments. Mildew is mainly found in plants and act as plant fungal pathogens.
Molds are black or green in color. Mildew is white to grey, yellow or green in color.
Black molds appear as fluffy colonies which penetrated from the surface. Mildew appears as flat colonies which attached to the surface.
Cladosporium, Aspergillus, and Penicillium are few examples of molds. Species belonging to the families Erysiphaceae and Peronosporaceae are examples for mildew.

Summary – Black Mold vs Mildew 

Fungal species can be both beneficial or deleterious. Black molds and mildews are two filamentous, spore-forming fungi which cause many allergic responses and irritations due to its spreading in indoor and outdoor environments. Molds are mildew share several common characteristics.

However, they differ in size, colour and appearance. Black molds, as the name suggest appear in black on walls and other moist places. Mildews, which are of two types; Powdery mildew and downy mildew are primarily involved in causing plant diseases.

It is utmost important to control the spreading of these fungal species to prevent health complications. Suitable fungicides and antifungal reagents or agents can be used for above purpose.


1.“Facts about Stachybotryschartarum and Other Molds.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 18 Sept. 2012. Available here 

2. Difference Between Black Mold and Mildew Availble here

Image Courtesy:

1.’Mould and Age’by Kristopha Hohn (CC BY-SA 2.0) via Flickr
2.’Downy and Powdery mildew on grape leaf’By  Agne27 at English Wikipedia (Public Domain) via Commons Wikimedia

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