Mold Types

Mold Facts

• Mold is a type of fungus. Other types of fungi include yeasts and mushrooms.
• Sometimes the term mildew is used. It is also a type of fungus.
• Molds reproduce by means of spores which commonly travel through the air.
• Mold can look like a smudge, a discoloration, or even a stain.
• Many smell musty or faintly like alcohol.
• Mold's most important requirement is a source of moisture. (e.g., basements, bathrooms, kitchens, carpet, upholstery, soil)
• Molds play an important role: as a part of the decaying process, as an antibiotic (Penicillin), and to flavor some cheeses.
• Some varieties of molds are toxic.

Mold Allergenicity

• Molds are strong allergens. However, most people are not allergic to molds.
• They are most numerous in the warmer months, but can be found year round.
• The spores can be inhaled or make contact through the eyes.
• In many climates, for each pollen grain in the air there are 1000 mold spores.
• Mold exposure increases with cutting the grass, raking dead leaves, or working with hay or mulch piles.

The Molds

Alternaria

• Recognized as the chief fungal cause of hay fever.
• Considered a dry weather spore. During dry periods, fungi increase in number until noon and decrease throughout the evening.
• Alternaria is considered an "opportunistic fungi" being commonly found in dust in upholstery, carpet, mildew, pet areas, and airborne in homes.
• In nature it is found in dead and dying plants and the soil.

Ascomycetes

• Also known as ascospores, they are considered a wet weather spore. Plentiful during light rainfall or in pre-dawn hours when condensation is heavy.
• Found everywhere in nature.

Aspergillus

• Aspergillus is considered an "opportunistic fungi" being commonly found airborne and in mildew in homes.
• Pose a danger indoors because they can grow in just a few days.
• It is reported to be allergenic.
• Found in warm soil, foods and dairy products.
• Very similar to spores of Penicillium.

Basidiomycetes

• Also known as basidiospores, they are considered allergenic.
• Considered a wet weather spore. Plentiful during light rainfall or in pre-dawn hours when condensation is heavy.
• The spores are delicate and need the cool, moist conditions of spring and early summer.
• Spores are not transported long distances or in large numbers.
• These spores come from mushrooms, puffballs, and bracket fungi. Found in lawns, fields, parks, and wooded areas from spring through fall within a few days after rainfall.
• In mushrooms and bracket fungi, the release of spores requires high humidity and so are most abundant in the pre-dawn hours.
• In puffballs, spores are released as rain drops strike them, with strong gusts of wind, or when small animals hit them.

Botrytis

• Reported to be allergenic.
• It is parasitic on plants and soft fruits.
• Found in soil and vegetables.
• Possibly associated with allergic symptoms.

Cercospora

• Parasite of higher plants, causing leaf spot.
• Common outdoors in agricultural areas, especially during harvest.

Cladosporium

• Considered a dry weather spore. During dry periods, fungi increase in number until noon and decrease throughout the evening.
• Cladosporium is considered an "opportunistic fungi" being commonly found in upholstery, pet areas, in mildew, and airborne in homes.
• Pose a danger indoors because they can grow in just a few days.
• Found in dead and living plant material.
• The most prevalent spore to be found in outdoor air samples.

Curvularia

• Reported to be allergenic.

Drechslera

• Is a common allergen.
• Found in plant debris and soil.
• Considered a plant pathogen of numerous plants, particularly grasses.

Epicoccum

• Considered a dry weather spore. During dry periods, fungi increase in number until noon and decrease throughout the evening. Reaches its peak around 10 AM.
• It produces spores rapidly and can grow under conditions of low humidity.
• Has been reported to cause plant diseases in trees and damage crops such as millet, corn, soy beans and agricultural grasses.
• Spores are buoyant and travel considerable distances in air.
• A common allergen, but not "highly allergenic".
• Found in a wide variety of plants, soil, air, human skin, insects, and a number of textiles.
• Spores are at their peak from August to October.

Fusarium

• A common soil fungus.
• It is found on a wide range of plants.
• It is often found in humidifiers.
• Several species in this genus can produce potent toxins.
• Reported to be allergenic.
• Frequently involved in eye, skin and nail infections.

Helminthosporium

• Reported to be allergenic.
• Found in plant debris and soil.
• Considered a plant pathogen of numerous plants, particularly grasses.

Myxomycetes

• Known as slime molds because they secrete a slime trail across their habitat as they move.
• Spores peak in early summer and into late fall.
• Affected by temperature and moisture. They need protection from the drying effects of the wind and sun.
• Tend to feed on bacteria.
• Found in the forest where it is generally cool, moist, and shady.
• Can be seen on decaying wood and in decaying leaves as colorful, shapeless structures.
• It is not a major plant pathogen.

Nigrospora

• Reported to be allergenic.
• Rarely found growing indoors.
• Found in decaying plant material and soil.

Penicillium

• Penicillium is considered an "opportunistic fungi" being commonly found in upholstery, carpet, wallpaper, insulation, pet areas, in mildew, and airborne in homes.
• Pose a danger indoors because they can grow in just a few days.
• Outdoors it is commonly found in soil, food, cellulose and grains. It is also found in paint and compost piles.
• Spores very similar to Aspergillus.

Periconia

• Cause of root-rot disease in sorghum cultivars.
• Found on the roots of various crops and dead plant stems.
• Spores are abundant in the air, but allergenicity is not well known.

Phoma

• A common indoor air allergen.
• Found in soil and associated plants, particularly potatoes.
• Produces pink and purple spots on painted walls.
• It will grow on butter, paint cement and rubber.

Pithomyces

• Spores found in dead stems, rotting leaves, paper, fodder grass, tree bark, and over 50 types of plants.
• Is an early colonizer of dead material and, once established, lasts well into the fall season.
• Spores are most abundant in the air between noon and 4 PM. Not as common in urban areas.
• Its allergenicity is not well known, but is a possible allergen due to its ability to colonize and persist for long periods of time. More likely to be a factor in rural areas.

Rhodotorula

• A reddish yeast typically found in moist environments such as carpeting, cooling coils and drain pans.
• In some countries it is the most common yeast genus identified in indoor air.
• This yeast has been reported to be allergenic.

Rusts

• It is a plant parasite.
• Named because of brown or orange color of the spores.
• The spores are designed to survive long distance transport.
• Often continue to produce spores well into the fall season.

Smuts

• Do not usually grow indoors.
• Considered an allergen.
• They are parasitic plant pathogens that require a living host for the completion of their life cycle.
• Found on cereal crops, grasses, weeds, other fungi, and on other flowering plants.
• Smuts are members of the Basidiomycetes.

Stachybotrys

• Pose a danger indoors because they can grow in just a few days.
• A slimy black mold rarely found indoors unless there has been water damage due to flooding or various leaks.
• May contain poisons that can cause internal bleeding in the lungs of infants.
• Because it needs cellulose to grow, it is found on drywall, ceiling tiles, and other materials containing paper or wood.
• In nature it is found with decaying plant materials.

Stemphylium

• Reported to be allergenic.
• Isolated from dead plants and cellulose materials.
• Although Stemphylium is rarely found growing indoors, it may be seen in dust as part of the normal influx of outdoor particles.

Torula

• Reported to be allergenic.
• Looks like a velvety black meal on various surfaces.
• Found on dead plant stems and leaves, wood, dung, and several crops.
• Spores are at their peak in the fall and late spring or early summer.
• Rated as the second highest level of spores in the United States after Aspergillus.

Trichoderma

• It is commonly found in soil, dead trees, pine needles, paper, unglazed ceramics.
• It often will grow on other fungi.
• It produces antibiotics which are toxic to humans.
• It has been reported to be allergenic.
• It readily degrades cellulose.