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Asian mushroom invades North American woodlands
An aggressive yellow-capped fungus from Asia is displacing native fungi across North America after escaping commercial cultivation, scientists warn.
How the golden oyster spread
The golden oyster mushroom (Pleurotus citrinopileatus) was imported to the United States in the early 2000s for food production. Its high yield made it popular with growers, but it soon escaped into the wild.
Mycologist Aishwarya Veerabuhu at the University of Wisconsin-Madison reports the species has now been detected in 25 U.S. states and one Canadian province. It has also established itself in Switzerland, Italy, Hungary, Serbia, Germany, and the southern UK.
"Community scientists were like, whoa! This thing is bright yellow, so it's very easy to notice."
Aishwarya Veerabuhu, University of Wisconsin-Madison
Ecological impact
Veerabuhu's team drilled into trees to analyze fungal communities. They found that trees colonized by golden oysters had roughly half the fungal biodiversity of uncolonized trees.
The mushroom decomposes wood rapidly, raising concerns about altered carbon cycles and habitat loss for species that depend on dead wood. Its carnivorous nature-preying on nematode worms-adds another layer of ecological disruption.
Global fungal invasions
The golden oyster is not the only invasive fungus. In October 2025, Poland's forest agency reported the North American slender golden bolete (Aureoboletus projectellus) in Białowieża Forest, a UNESCO site home to Europe's largest wild bison population.
Climate change is also expanding the range of tropical fungi. The orange "ping pong bat fungus" (Favolaschia calocera), native to Madagascar, has appeared in Dorset, England, though its impact remains unknown.
"When I started teaching mycology, fungi were plants. Now that we know fungi are their own kingdom, conservation efforts are finally catching up."
Anne Pringle, University of Wisconsin-Madison
Conservation efforts
The International Union for Conservation of Nature (IUCN) now lists over 1,300 threatened fungal species, up from just three in 2014. Citizen scientists and mycologists are cloning native fungi to preserve genetic diversity.
Andy Knott, founder of Jurassic Coast Mushrooms, runs cloning workshops to propagate native species like the grey oyster mushroom. His company supplies home growers with native strains to reduce reliance on invasive varieties.
"We clone them in the lab, then resupply as grain spawn. I want to be that guy-the seed bank for mushrooms."
Andy Knott, Jurassic Coast Mushrooms
Challenges ahead
Matthew Wainhouse of Natural England notes that golden oyster sightings in southern England are rising. He urges the public to report findings to the British Mycological Society.
Despite their ecological importance-fungi support 90% of land plants and create habitats for birds-conservation funding lags behind efforts for animals and plants. Wainhouse hopes growing public interest will help shift priorities.
For now, small actions like cloning workshops offer a glimmer of hope. As one participant at the UK's All Things Fungi Festival discovered, even a failed experiment can spark deeper curiosity about the hidden world beneath our feet.
