Golden Oyster Mushroom (Pleurotus citrinopileatus Singer) from Rock County, Wisconsin. Photo by Gary Shackelford, Mushroom Observer 278886, 14 June 2017.
Golden Oyster mushrooms (Pleurotus citrinopileatus) are hard not to like. Their bright yellow clusters stand out from almost any other cultivated mushroom, they have a delicate texture and nutty flavor, and they are relatively easy to grow. For those reasons, they have become popular with commercial mushroom farms and home growers alike.
They are also native to eastern Asia. Golden Oysters were brought to North America for cultivation in the early 2000s and escaped into the wild around 2010. Since then, they have spread rapidly through forests in the Midwest and eastern North America. By the time researchers published a major study of their spread in 2025, Golden Oysters had been reported in 25 U.S. states and one Canadian province.
From an escaped mushroom to an invasive species
Seeing a cultivated species growing in the wild doesn't necessarily mean that it is causing ecological harm. Golden Oysters have been known to escape cultivation for years, but until recently, there was much less information about what their presence might be doing to native fungal communities.
That began to change with research led by University of Wisconsin–Madison mycologist Aishwarya Veerabahu. In a 2025 study published in Current Biology, Veerabahu and her colleagues examined fungal communities in dead elm wood in south-central Wisconsin, comparing trees colonized by Golden Oysters with trees where Golden Oysters were absent.
The results were concerning.
The researchers found that fungal communities changed significantly when Golden Oysters were present and that the number of fungal species living in the wood was significantly lower. In short, the Golden Oysters weren't simply joining an existing community of fungi—they were associated with a less diverse fungal community.
"We were startled to find that trees with golden oyster mushrooms housed only half as many fungal species as trees without golden oyster mushrooms, sometimes even less," writes Veerabahu.
Why Native Fungi Matter
It can be easy to think of mushrooms as simply the fruiting bodies we see growing on logs or emerging from the forest floor. In reality, fungi are a fundamental part of forest ecosystems.
They decompose wood and other organic material, recycle nutrients such as carbon and nitrogen, interact with plants and animals, and help create the soil that supports future plant growth.
Golden Oysters are particularly aggressive wood decomposers. Their ability to colonize and break down dead wood quickly may change both the fungal communities occupying that wood and the amount of time dead wood remains available as habitat for other organisms. Researchers are continuing to study what those changes could mean for forest ecosystems over the long term.
The issue isn't limited to the United States, either. Golden Oysters have now been found growing outside cultivation in Europe. In 2026, the species was classified as a **high-risk invasive species in the United Kingdom** following confirmed appearances in English woodland.
Why Hazel Dell Is Making the Change
The fact that Golden Oysters can escape cultivation has been known for some time. What is newer is direct evidence that their presence is associated with reduced fungal diversity. That new research changed how we think about continuing to grow them commercially and offer them in grow kits.
We don't need Golden Oysters in order to offer a diverse selection of mushrooms, and continuing to cultivate them creates at least some possibility of contributing to additional introductions. For that reason, we've decided to stop producing them at Hazel Dell.
That means saying goodbye to a mushroom we genuinely enjoyed producing. It does not mean Golden Oysters are unsafe to eat, nor does it mean growers who cultivated them in the past knowingly caused an invasive-species problem. Much of what we now know about their ecological impact has only become clear through recent research.
Further Reading
For anyone interested in learning more about Golden Oysters and their spread, we recommend these resources:
“The Golden Oyster Mushroom Craze Unleashed an Invasive Species — and a Worrying New Study Shows It’s Harming Native Fungi” - Aishwarya Veerabahu, The Conversation, 2025
“Golden Oyster Mushroom Declared High-Risk Invasive Species in the UK” - MycoStories, 2026
"This Golden Fungus Is Spreading Wildly in North America’s Forests" -New York Times, 2025