A Popular Gourmet Mushroom Is Escaping Gardens and Invading US Forests

Golden oyster mushrooms arrived in the United States in the early 2010s. The canary-colored, fluffy mushrooms have since gained popularity as an aesthetically pleasing, tasty addition to numerous recipes—sold in grocery stores, farmers markets, and, more recently, as staple grow-your-own kits for casual gardeners.

But these foreign mushrooms—native to the hardwood forests of East Asia and Russia—come with “great responsibility when growing,†according to conservation scientists at the University of Wisconsin-Madison and the University of Florida. In fact, the team warned, the golden oyster invasion has already disrupted a significant portion of the native mushroom ecology in the United States. Suffice to say, these mushrooms are an invasive species.

Their findings, derived from a recent field study, were reported in a paper published in late summer in Current Biology. In addition to recording golden oyster mushroom presence across affected states, the researchers developed a model to predict the proliferation of the mushrooms in the coming years. Overall, it was clear that where golden oyster mushrooms thrived, native fungal communities struggled.

“Even though it’s a beautiful, edible species, it’s now proven capable of escaping cultivation and spreading into natural forests, where it can outcompete native fungi,†the researchers explained in a statement.

The march of the mushrooms

For the study, the researchers first collected empirical data on the mushrooms, including from community science platforms such as iNaturalist and Mushroom Observer. This allowed them to create a map of how the exotic mushrooms spread across the East Coast since 2016.

“It is slowly marching south, which is really terrifying,†said Michelle Jusino, study senior author and a conservation scientist at the University of Florida, in the statement. “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.â€

To assess environmental impact, the team compared samples from dead elm trees with and without the golden oyster mushrooms. DNA-based techniques revealed a concerning decrease of native fungal species, including mushrooms with medicinal or ecological importance, on samples with many golden oyster mushrooms.

While a small number of species still flourished alongside the golden oysters, it was evident that the “aggressively invasive†mushrooms were displacing local mushrooms, the study concluded.

Cultivated fungi escape

This isn’t the first time experts have expressed concern about these mushrooms, with certain industry stakeholders choosing not to deal with them. Despite these precautions, the golden oyster mushrooms are thriving because they are capable of spreading their spores “under the radar,†the researchers explained.

Unlike invasive animals, insects, or even plants, microbial invasions are extremely difficult to track, purely due to their general invisibility.

“We want to remind growers that not all cultivated fungi stay where we put them,†Jusino said. “Once released outdoors, even accidentally, the golden oyster mushroom can spread quickly and outcompete native species.â€

Indeed, this “quiet†invasion highlights a serious research gap in monitoring very tiny invasive species, Jusino said, adding, “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.â€