With its bright yellow, cushion-like caps, the golden oyster mushroom has become a favorite among home growers and food lovers. It is widely available in grow-your-own kits and sold in grocery stores, farmers markets, and specialty shops. However, a University of Florida researcher warns that this appealing mushroom is quietly spreading into natural forests and is now appearing in markets across Florida.
Michelle Jusino, assistant professor of forest pathology at the School of Forest, Fisheries, and Geomatic Sciences at the Institute of Food and Agricultural Sciences (UF/IFAS), says that growing this popular species comes with important responsibilities. While it is prized in the kitchen, it may not remain contained once introduced outdoors.
"The golden oyster mushroom may look harmless on a log, but it appears to be a strong competitor in the forest," she said. "It is associated with changes in the fungal community, reducing biodiversity and potentially affecting processes like wood decomposition and carbon cycling."
Human Activity Driving Mushroom Spread Across the US
Jusino's warning follows a recently published field study in Wisconsin that she helped design during her time with the U.S. Forest Service. The research highlights how everyday human activities, including purchasing, cultivating, and transporting mushrooms, can unintentionally introduce invasive species into new environments.
To track the spread, researchers relied on community science platforms such as iNaturalist and Mushroom Observer. These records allowed them to map sightings of the golden oyster mushroom across North America. In roughly ten years, the species has expanded into more than 25 U.S. states, including Texas, District of Colombia, Virginia, North Carolina, Alabama, and Louisiana. Earlier research by Andrea Bruce suggests the mushroom first entered the wild in the United States in the early 2010s.
"It is slowly marching south, which is really terrifying," said Jusino. "In 2016, the mushroom was found growing in the wild in just five states, all in the Midwest and Northeast, but today I think fewer than 10 states east of the Mississippi river remain without records of golden oyster in the wild."
Study Shows Impact on Native Forest Fungi
To better understand its ecological effects, Jusino and her colleagues studied dead elm trees both with and without golden oyster mushrooms. They collected wood samples from different heights on each tree and used DNA-based methods to identify the fungi present.
The findings revealed clear differences. Trees colonized by golden oyster mushrooms contained far fewer fungal species, and the overall mix of fungi was altered compared to unaffected trees. Some native fungi, including those with ecological or medicinal importance, were reduced, while only a small number of species seemed able to coexist with the invasive mushroom.
"We want to remind growers that not all cultivated fungi stay where we put them. Once released outdoors, even accidentally, the golden oyster mushroom can spread quickly and outcompete native species," said Jusino.
Why Fungal Biodiversity Matters
Researchers emphasize that preventing further spread will require increased awareness, careful monitoring, and a preference for using native mushroom species. Jusino is also continuing to test new methods to better understand and manage the issue.
As reports of golden oyster mushrooms continue to grow, scientists stress that even edible fungi can have wide-ranging ecological effects. Protecting native fungal biodiversity is critical for maintaining healthy forests and preserving the genetic diversity needed to adapt to climate change.
Although it is an attractive and edible species, the golden oyster mushroom has demonstrated its ability to escape cultivation and establish itself in the wild, where it can outcompete native fungi.
A Hidden Threat From Invasive Microbes
Jusino's work also points to a broader challenge. Microbial invasions often receive far less attention than invasive plants, insects, or animals, yet they can significantly alter ecosystems. Fungi and bacteria may spread unnoticed while reshaping the balance of life in forests.
"Invasive fungi are part of the biodiversity crisis," she said. "They're small, but their impact can be enormous. Paying attention now gives us a chance to protect native ecosystems before the balance tips too far."
