“Tracing the Naturalization of Golden Oysters in the U.S.”

A BIT OF BACKGROUND

On the 2012 Galena, Illinois morel foray, they first appeared, the golden oyster mushroom (Pleurotus citrinopileatus). I knew what they were but thought to myself “they shouldn’t be here because they are only commercially grown”. Pics below:

Since then, I have seen a steady growth in quantities of these delicious mushrooms at the same location. Recently, we harvested over 100 pounds there during the foray! They are so colorful, and yet so delicious! Recent foray pics below:

About 20 years ago, it was near impossible to find them on the American market.  It’s native to subtropical hardwood forests of eastern Russia, northern China, and Japan, and has long been a popular culinary mushroom for cultivation across Asia.  Its sunny yellow caps make this species a show-stopper at farmers markets, and its popularity State-side has steadily risen over the years among specialty mushroom growers.

Today, it’s reasonably common to find golden oysters at American farmers markets during the summer, as it requires temps consistently above 60º F to fruit.  In Growing Gourmet and Medicinal Mushrooms, Stamets writes: “With the onset of commercial cultivation of these mushrooms adjacent to woodlands in North America, it will be interesting to see if these exotic varieties escape.”  I’d guess Stamets was spot on, but this is among the details regarding the mushrooms’ spread that my research seeks to confirm.  The first sightings of wild golden oysters in the US seemed to have occurred just about 6 or 7 years ago, following the rise in American cultivation of the species.  I have collected reports of sightings in Delaware, Illinois, Iowa, Maryland, Michigan, Minnesota, New York, Pennsylvania, and Wisconsin.

ARE GOLDEN OYSTERS INVASIVE?

The term “invasive” can be defined in many ways.  Ecologist Dr. Elena Litchman defines invasive microorganisms as those which proliferate in a new range and impact local communities or ecosystems.  This description leaves little doubt that golden oysters indeed fall under the category of invasive.  We would be rather negligent to assume that the rapid spread of any non-native species would be inconsequential to native ecosystems.  The golden oysters’ swift spread suggests that the native decomposers are being outcompeted and displaced.  Climate change and habitat loss already pose major threats to fungal biodiversity, so it’s critical that we understand the role non-native fungi play in deepening those threats.  Fungi provide vital ecosystem services as a part of diverse microbial communities, and ecological studies have shown that losses to biodiversity, or reductions in species richness, have negative effects on ecosystem function.

RESEARCH

Although outdoor cultivation is common practice, this is the first ever case of escape with rapid and significant spread of a cultivated mushroom.  I’m using genomic data (the entire DNA sequence of every specimen, rather than targeting specific gene regions) to analyze the ancestral lineages of our samples, allowing us to get a better understanding of the mechanisms behind their spread.  This sort of information will help us understand how humans have influenced the spread of golden oysters, and may provide a starting block for the development of mitigation procedures.

They have also appeared during my fall forays in Galena and also continue to grow in frequency. Last yr’s fall pic below:

They are super easy to grow and I always bring home a big batch of the butt-ends of them from Galena and have had very good luck and so much fun growing them and watching them mature. My most recent fruiting pic below:

They dry and freeze extremely well. Way better than regular wild oysters. I use them in so many dishes, I could write a cookbook just using them! In any event, I welcome this species to the wilds of the US and and am always on the lookout for that bright golden yellow color in both spring and fall and hope they will continue to spread in coverage! (I am guilty of planting a few on dead wood in any new areas so we will see what happens)! Below is a current map of golden oyster’s range:

Finally, below is a gallery of finds so far this spring… Enjoy!

Email Chris for questions, comments or additional submissions and info: chris@morelmushroomhunting.com