All About Cladosporium: The Common Genus of Indoor Mold


Cladosporium is one of the most common genres of indoor mold found in homes and buildings. This genus contains over 772 species, making it one of the largest groups of fungi. Understanding what cladosporium mold is, where it grows, how to identify it, and its health effects is important for home and building owners.

What is Cladosporium Mold?

Cladosporium is a genus of molds that belongs to the family Cladosporiaceae and order Capnodiales. It is classified under the class Dothideomycetes in the phylum Ascomycota. This means cladosporium is a type of sac fungus that reproduces sexually through the release of ascospores from an ascus.

The most distinctive feature of cladosporium mold is the profusions of dry, olive green to brown conidia (asexual spores) formed in branched chains at the ends of hyphae called conidiophores. The conidia easily become airborne due to wind or airflow disturbances. These airborne spores allow cladosporium to easily disperse and colonize new environments.

Over 772 species of cladosporium mold have been discovered so far. Some common indoor cladosporium species are C. herbarum, C. cladosporioides, C. sphaerospermum, and C. elatum. Cladosporium fulvum is known for infecting tomato plants while C. tenuissimum causes skin infections. The type species for this genus is C. herbarum, which was first described in 1816.

What Does Cladosporium Mold Smell Like?

The most common descriptions of typical Cladosporium odor are earthy, woody, and damp smelling. The fungi produce no metabolic gases or fragrances on their own. Any associated scents come from microbial volatile organic compounds interacting with growth substrates.

The mustiness results from cellulose or other materials decaying under chronic moisture. If smell resembles rotten leaves, compost, or forest soil mixed with old dirty mop water, Cladosporium may be present. Any detection warrants investigation of water intrusion sites and indoor humidity levels.

An extremely foul, pungent stench suggests additional anaerobic bacteria from longstanding extreme dampness. Other molds like Stachybotrys chartarum also smell stronger. But most Cladosporium itself has a mild, mossy character fitting its ubiquitous environmental dispersal.

Where Does Genus Cladosporium Grow?

Cladosporium is a very common mold both indoors and outdoors. As a cosmopolitan mold, cladosporium can grow in a wide range of environments and temperatures.

Outdoors, cladosporium is commonly found in soil, on dead plants and rotting vegetables, textiles, and rubber. Some cladosporium species act as plant pathogens.

Indoors, cladosporium grows on a variety of building materials that can supply enough moisture and organic matter. It is most commonly found on:

  • Drywall
  • Paint
  • Textiles like carpet, fabric curtains
  • Wood materials
  • HVAC insulation
  • Bathroom tiles and caulking
  • Window sills and frames

Any surface that remains damp for over 48 hours due to water leaks, flooding, or high humidity can allow cladosporium colonies to become established.

How Quickly Does Cladosporium Mold Grow?

With ready moisture and nutrients, Cladosporium spreads rapidly thanks to profuse conidia production. Each daylight period can yield new cohorts of spores if conditions permit. Mycelial mats advance outward seeking fresh resources, while aerialaerosols disperse clones ubiquitously.

Within just 48 hours of settling on suitable damp substrate, Cladosporium germinates and forms visible colonies. These expand to powdery or velvety status filling several inches over two weeks. Given greater time, extensive contamination and even fruiting bodies emerge.

Speed is influenced by:

  • Temperatures: Optimal around 86°F, but still active down to 50°F and up to 95°F
  • Humidity: Minimum 70%, ideally above 90%, on permeable material
  • Nutrients: Readily uses cellulose, adhesives, wall cavity organics
  • pH: Prefers acidic conditions ~3 to 6

Warmer seasons intensify growth rates when heating and cooling cycles increase condensation. But wintertime infestations still occur on chronic drought-prone surfaces.

Regular cleaning, moisture control and maintenance keep buildings unfavorable for rapid mold expansion. Monitoring shows early signs allowing quicker remediation.

How to Identify Cladosporium Mold

Identifying cladosporium visually usually involves looking for the trademark powdery, olive-green to brown spots that this mold forms. The colors can also appear grey, yellow, or black depending on age and species.

Under a microscope, cladosporium mold has visually distinct branched conidiophores that look like trees with chains of oval or round shaped conidia forming at the ends. The conidia form in a zig-zag or double row pattern.

Cladosporium mold also has a faint sweet and dry smell though this isn’t always distinguishable. Taking air samples or swab samples for lab testing usually provides a definitive identification through DNA analysis or culturing methods.

Here are the key identification points for cladosporium mold:

  • Olive green, grey, brown, yellow or black spots
  • Powdery or velvety texture
  • Branched conidiophores under a microscope
  • Chains of oval or round shaped conidia
  • Distinct zig-zag or double row formation of conidia
  • Sweet, earthy, musty or dry smell (sometimes)

Proper identification requires laboratory testing of samples by a professional mold testing company. Visual inspections alone can sometimes result in misidentification.

Is Cladosporium the Same as Black Mold?

Cladosporium is different from the home repair nightmare known as “black mold.” The dark growth called Stachybotrys chartarum has more alarming toxicity and health effects. It requires very damp conditions like flooding versus Cladosporium’s lighter moisture demands.

Differences include:


  • Olive, grayish-green to black colonies
  • Velvety or powdery texture
  • Colonizes at lower humidity
  • Primarily an allergen rather than toxin producer
  • More ubiquitous in temperate regions


  • Jet black and slimy surface sheen
  • Colonizes materials very wet for prolonged periods
  • Produces trichothecene mycotoxins severely harmful if ingested or inhaled
  • Limited temperature tolerance

So while Cladosporium discoloration may look dark from a distance, close inspection reveals a fuzzier gray-green surface. Stachybotrys is wetter, sticker and evokes rotting leaves. Always confirm mold species through expert lab analysis when health concerns arise.

Health Effects of Cladosporium Mold Exposure

Cladosporium mold ranks as one of the top allergenic molds along with aspergillus and penicillium species. The tiny 3-5 μm conidia easily enter the lungs when airborne causing allergic reactions in sensitive individuals.

Some health effects linked to cladosporium exposure include:

  • Runny nose, itchy eyes, coughing, sneezing
  • Skin irritation – rashes, dermatitis
  • Asthma attacks and worsened respiratory problems
  • Hypersensitivity pneumonitis
  • Sinus congestion, infections
  • Headaches, fatigue
  • Irritation and infections if spores enter open wounds

People with asthma, allergies, or weak immune systems face higher risks when exposed to cladosporium spores. While less common, cladosporium can sometimes cause fungal ball infections in sinuses or deeper systemic infections in immunocompromised patients.

Myotoxic, immunosuppressive, and neurotoxic metabolites have been found in some cladosporium species which raises concerns over toxin production. However, more research is still needed regarding the toxigenic capacities across the numerous species in this genus.

What Kills Cladosporium Mold?

To kill active Cladosporium mold after identifying and fixing dampness issues, an EPA-registered antimicrobial product suitable for fungi should be applied. Bleach solutions are not recommended, as they react with mold material to produce irritating byproducts.

Common antimicrobial ingredients proven effective against Cladosporium and other molds include:

  • Isothiazolinones
  • Sodium hypochlorite
  • Hydrogen peroxide
  • Thymol
  • Ethanol/isopropanol
  • Peracetic acid
  • Glutaraldehyde

Compare product labels and safety data sheets to choose the best fungicide for your purposes. Application methods range from ready-to-use trigger sprays to wipes, foggers, surface coatings and professional products optimizing contact time.

For preventive mold inhibition without killing existing growth, weaker essential oil treatments using tea tree oil, clove oil, eucalyptus oil or thyme oil can restrain spore production and new colonies. But manual removal is still required first.

Biocidal treatment should always be combined with fixing dampness sources. And any extensive fungal contamination requires remediation or material replacement to really solve the problem.

Mold Removal and Remediation Guidelines

If cladosporium mold is spotted within a home, school, hospital or office building, prompt assessment and remediation are crucial. Mold growth lasting over 48 hours increases health risks from spore inhalation and mycotoxin exposures if species are toxigenic.

Guidelines for cladosporium mold removal include:

  • Identify all contaminated materials using inspection and air/swab sampling
  • Isolate the affected area using containment barriers
  • Use HEPA air scrubbers to trap spores
  • Dispose of porous materials like drywall and fabrics if growth covers over 10 square feet or visible mold over 25 square feet
  • Clean hard surfaces using detergent or fungicidal disinfectants
  • Dry out any underlying moisture sources like leaks
  • Follow up with inspection and testing to confirm mold removal before taking down containment

In some cases, calling a professional mold remediation company provides the best results when contamination is extensive or in difficult to reach HVAC systems. Residual mold growth can lead to recurring exposures if the full extent is not eliminated.

Ecology and Occurrence of Cladosporium

Cladosporium mold plays important ecological roles both outdoors and indoors by breaking down organic matter. Outdoors, many species act as initial colonizers after fires, on dead plants, or on other fungi. Indoors, cladosporium competes with other molds like aspergillus and penicillium.

As a cosmopolitan and highly air dispersed genus, cladosporium mold can grow in diverse environments across wide temperature, pH and moisture ranges:

  • Temperatures: Can grow between 0°C to 40°C but optimally between 15°C to 30°C
  • pH levels: Grows in acidic to neutral pH from 2 to 7+
  • Moisture: Capable of tolerating dry conditions but thrives at high humidity up to 100% RH
  • Nutrients: Cellulose, hemicellulose, proteins, oils, fats and other organic matter
  • Global distribution: Found across all inhabited continents

The adaptability of cladosporium allows both outdoor-to-indoor and local dispersal through open windows, doors, ventilation systems and even small wall cracks allowing some spores through. Identifying and removing indoor reservoir populations limits further dispersal.

Importance and Uses of Cladosporium Fungi

Despite causing allergy and infection risks in indoor environments, cladosporium species also have some beneficial medical and commercial uses.

Some species show antimicrobial properties against certain bacteria that may prove pharmacologically useful with further research. The pigments made by species like C. herbarum also show therapeutic potential according to emerging research.

Additionally, cladosporium species play key roles in bioremediation and biodegradation processes to break down oil spills, textile dyes, polycyclic aromatic hydrocarbons, and other pollutants. The enzymes and metabolites produced by these fungi aid in environmental cleanup processes.

Key Takeaways

Cladosporium mold is one of the most common indoor molds widely dispersed through its airborne spores. Exposure for sensitive individuals can lead to allergy symptoms or potentially infection risks. Timely mold testing and removal help limit contact and improve indoor air quality.

While cladosporium poses risks in indoor living spaces, this adaptable genus also offers potential uses for medicine development and bioremediation applications. Further research continues illuminating new species and properties of these ubiquitous molds.

Understanding what promotes or limits cladosporium growth indoors provides homeowners, building managers, medical professionals and others key insights on prevention and response when facing contamination issues. Ensuring buildings have adequate ventilation, moisture controls, and cleaning protocols helps create healthier indoor spaces.

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Southeast Water Restoration
Southeast Water Restoration specializes in water damage restoration, mold remediation, and 24/7 emergency services for water-related issues in Georgia. Expertly handling flood damage, pipe bursts, and sewage backups, we use state-of-the-art dehumidifiers and water extractors. Our IICRC-certified team ensures top standards in water damage repair and mold safety. We serve Athens, Buford, Monroe, Atlanta, Conyers, Cumming, Roswell, Marietta, East Cobb, Alpharetta, Gainesville, Dacula, Winder, Decatur, Lawrenceville, Sandy Springs, Hoschton, Big Creek, Loganville, and Buckhead. Our commitment to health and safety is paramount, addressing concerns like black mold and indoor air quality.

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