Fusarium is a common, naturally occurring mold genus with many species. While many are harmless, some can cause issues for plants, animals, and humans. Its presence can be indicated by colors ranging from white, tan, and salmon to pink, red-violet, or purple, and sometimes it may appear cottony or wooly in texture. This mold thrives in damp conditions and spreads via airborne spores.
In Natural Environments
Fusarium mold is primarily found in soil, where it acts as a significant plant pathogen. It is widespread globally, affecting various agricultural and horticultural settings, including fields, gardens, and forests. This fungus can persist in soil for many years, often as resilient chlamydospores, which are thick-walled resting structures.
The mold infiltrates plants through their root systems, particularly through wounds caused by cultivation or nematodes. Once inside, it can disrupt the plant’s water transport system, leading to symptoms like wilting, yellowing leaves, stunting, and eventual plant death.
Fusarium wilt, caused by species like Fusarium oxysporum, can impact economically important crops such as tomatoes, sweet potatoes, bananas, and legumes. For instance, a particular strain of F. oxysporum severely impacted the commercial banana industry.
Fusarium species can cause a range of plant diseases including crown rot, head blight, and scab, particularly in cereals like wheat, corn, barley, oats, rye, and triticale. Fusarium graminearum is a notable species that causes head blight in these grains, leading to substantial agricultural losses. This mold can also affect other plants such as asparagus, figs, and soybeans.
In Agricultural Products and Food
Fusarium mold can contaminate agricultural products and food both before and after harvest. It commonly contaminates cereal grains. This contamination often occurs during the growing season, especially under wet and cool weather conditions. The mold can produce mycotoxins, such as deoxynivalenol (DON), zearalenone (ZEA), and fumonisins, which can pose risks to human and animal health.
After harvest, Fusarium can continue to grow on stored grains and other food products if conditions are favorable. Improper storage with high humidity, poor ventilation, or insect infestations can intensify mold growth and mycotoxin production. Beyond grains, Fusarium species have been identified on various fruits and vegetables, including tomatoes, melons, squash, and citrus fruits, often entering through cuts or damage.
Mycotoxins produced by Fusarium are heat-stable, meaning they can remain in food even after processing, such as pasteurization. This highlights the importance of managing contamination throughout the food production chain, from field to storage. While some Fusarium species are harmful, one species, Fusarium venenatum, is used in the production of Quorn, a meat substitute.
In Indoor Spaces
Fusarium mold is also commonly found in indoor environments, particularly in areas with elevated moisture levels. It thrives in damp locations within homes and buildings, such as bathrooms, basements, crawl spaces, and areas affected by water damage. The presence of Fusarium indoors often indicates an underlying water issue, such as leaks or high humidity.
This mold can colonize various building materials that absorb moisture. Common surfaces where Fusarium may grow include drywall, carpets, wallpaper, and wood. It can also be found in fabrics, on windowsills, in houseplants, and within HVAC systems, especially in humidifier pans or areas with stagnant water. Spores can enter homes through moldy food, indoor plants, or by being carried in from the outside air.
While Fusarium spores can become airborne, particularly when dry, their presence indoors often suggests active growth on a damp substrate. If left unaddressed, Fusarium mold can cause damage to structural surfaces like drywall and wood, potentially leading to deterioration over time.