A Beautiful Mushroom… but One We Need to Know Thoroughly

In recent years, the Golden Oyster (Pleurotus citrinopileatus) has become one of the most popular mushrooms in gourmet cultivation. Its bright yellow color, rapid growth, and delicate aroma have made it one of the preferred species for mushroom growers.

But as often happens in nature, beauty can have a downside. Recent studies conducted in the United States are raising an important question: can this mushroom, introduced from East Asia, adapt and reproduce in natural environments outside of cultivation areas?

Origin and Spread of the Golden Oyster

The Golden Oyster is native to eastern Russia, China, and Japan. It belongs to the genus Pleurotus, the same as the common oyster mushroom (Pleurotus ostreatus), but is distinguished by its golden cap and greater tolerance of high temperatures.

Since the 2000s, the Golden Oyster has been introduced to Europe and North America for commercial purposes: it is easy to grow, visually striking, and highly profitable.

However, in Italy, many large cultivation companies market this species under the incorrect name of Pleurotus cornucopiae, which is actually a species native to our country.

This can cause confusion, as in most cases it is actually Pleurotus citrinopileatus—the true Asian-origin “Golden Oyster”—rather than the European P. cornucopiae.

What Does “Invasive” Mean for a Mushroom?

When talking about invasive species, people often think of plants or animals, but mushrooms can also colonize new environments in unexpected ways. In ecology, three categories are distinguished:

• Introduced species: brought by humans to a new territory.
• Naturalized species: able to reproduce spontaneously in the new environment.
• Invasive species: actively spreads, competing with native species.

In the case of the Golden Oyster, some field observations indicate that in certain areas of the United States, the mushroom is fruiting spontaneously on logs and dead wood in natural environments, far from the cultivation areas from which it originated.

Early Reports in North America

In recent years, U.S. researchers have documented the presence of the Golden Oyster in the wild.

A recent study conducted by the University of Wisconsin–Madison highlighted that the presence of this mushroom in Wisconsin forests can have negative effects on local biodiversity.

Analyses conducted on logs colonized by the Golden Oyster show a profound alteration of the fungal communities inhabiting the wood and a significant reduction in species diversity.

What does this mean?

That when the Golden Oyster establishes itself in a natural ecosystem, it alters the ecological balance of the forest and can contribute, over time, to the local disappearance of native fungal species.

Source: Veerabahu et al. Invasive golden oyster mushrooms are disrupting native fungal communities as they spread throughout North America. (2025)

The Situation in Italy

Currently, there are no studies exploring the presence of the Golden Oyster in Italy or elsewhere in the European Union. It is not yet clear whether this species is naturalized in Italy. However, there have been observations reported on the iNaturalist platform, which may indicate a possible presence of these species in natural environments. Most of the observations in Europe appear to be in Italy. 

During a direct conversation with Aishwarya Veerabahu, a researcher at the University of Wisconsin-Madison, we were told that preliminary distribution models of the species show that most of Europe—with the exception of northeastern areas, including Finland and Russia—and especially the Italian peninsula, has climatic conditions favorable to the establishment of the Golden Oyster. 

These studies serve as a warning: if an introduced species is able to reproduce independently, it means it can interact with local fungal communities and, over time, alter them.

The Ecological Risk

It is important to be clear: the Golden Oyster is not yet recognized as an invasive species, but it is a species that needs to be carefully monitored.

If it begins to spread, its spread could be rapid and unpredictable, with trajectories that are difficult to anticipate.

Potential risks include:

• Competition with other native species and local decomposers.
• Alterations of wood decomposition cycles and carbon emissions
• Extinction of native species
• Alteration of native fungal communities and forest ecosystems.
  
• Reduction of biodiversity of species associated with dead wood. 
  

To date, no control strategy is available.

Cultivating Responsibly

Being a grower today also means being a steward of biodiversity. 

The responsibility of the sector is not only to produce quality mushrooms, but also to protect the ecosystems that surround us. Therefore, as a cultivation company, Growers of Mushroom declares that:

"Having assessed the evidence currently available regarding the risk of invasion in Italian territory and the possible environmental damage that may result, as a company, we will stop selling Golden Oyster cultures, grain spawn, and cultivation kits (Pleurotus citrinopileatus). This is to stop and no longer contribute to the release of spores of this species into the environment. 

We invite all mushroom growers in Italy to remove P. citrinopileatus and P. cornucopiae from their production and to join us in raising awareness about this issue. 

In addition to this, we have decided to create an observatory to collect data on the presence of P. citrinopileatus in the ecosystems of our peninsula."

The Project: the Citrinopileatus Observatory

To contribute concretely to the knowledge and management of this species, Growers of Mushroom has launched the Citrinopileatus Observatory, the first Italian data collection project dedicated exclusively to this mushroom.

The goal is:

• Collect and verify reports of possible presences in nature.
• Collaborate with researchers who are studying the phenomenon internationally.
• Raise awareness within the cultivation sector about more sustainable practices.

👉 Participate in the Golden Oyster Observatory
Contribute by sending photos, coordinates, and direct observations. All collected data are sent to researchers who are analyzing the spread of the species in nature.

Conclusion – Cultivating Awareness, Not Just Mushrooms

The Golden Oyster is a marvel of nature: elegant, productive, and delicious.
But the time has come, as growers, to take responsibility for cultivating with ecological awareness.
We are, first and foremost, lovers of nature and stewards of these organisms that offer us so much—the very same mushrooms that make our work possible and deserve to be respected and protected.

What Can You Do as a Grower?

• Prioritize native species from your territory, preferably with local genetics.
• Avoid spore dispersal: use sterile cultures or harvest mushrooms before they reach maturity and release spores (e.g., Reishi).
• Educate your community and your customers about the environmental risks associated with invasive species.
• Involve everyone in the Citrinopileatus Observatory project, contributing to data collection and the protection of local ecosystems.