pink oyster mushroom

 

The rising popularity of home mushroom-growing could lead to a biodiversity disaster, UK garden experts have warned.

With more people cultivating mushrooms in their gardens, the RHS Chelsea Flower Show’s plant of the year award even included a mushroom—the tarragon oyster mushroom, native to the British Isles—for the first time.

Kew Gardens in southwest London has reported an increase in inquiries about garden mushroom cultivation after installing new mushroom beds in their kitchen garden. Researchers are exploring the beneficial interactions between plants and mycorrhizal fungi, noting that native mushrooms can enrich the soil and form symbiotic relationships with plants.

However, concerns are growing about non-native mushrooms potentially causing biodiversity issues if grown in gardens or discarded in compost heaps.

Similar to invasive species like Japanese knotweed, rhododendron, and bamboo, non-native fungi are difficult to remove once established, as they spread through tiny mycelia and spores.

Native fungi play a crucial role in the garden ecosystem by decomposing dead plant and animal matter, converting it into nutrients that plants can use. These fungi are essential for breaking down organic material into humus, minerals, and nutrients.

Sheila Das, a garden manager at RHS Wisley, expressed concerns that exotic fungi could spread through the soil, alter microbiology, and become nearly impossible to eradicate.

She said: “The opportunities we have to grow edible fungi at home are extremely exciting. We should make sure when buying kits for growing that we are purchasing from trusted suppliers.

“We are still learning much about the world of fungi, so introducing alien spawn into your garden by accident (ie species not native to this country) could potentially unlock many issues just as we have learned from the past with invasive plants and imported plant diseases.

“Alien fungi could potentially be even harder to control than alien plant species as their manner of growth is so complex and they can spread throughout soil and other organisms very quickly.

“Many home kits are designed for growing indoors, but people are often encouraged to dispose of them on their compost heap or in the garden, so having fungi that belong in the UK is important when we think of its full life cycle.”

Experts advise selecting mushroom grow kits featuring species native to the UK to prevent these issues.

Dr Ruth Chitty, an RHS plant pathologist, said: “There are a lot of gaps in our knowledge about introducing mushroom spawn from different countries. Research has found different populations across the world have some genetic variation, and we are not sure what impact introducing a different population will have on the UK populations.

“There is a possibility that the introduction of species from other countries will have negative effects such as outcompeting native species. There are mushroom growing kits for sale that contain UK collected spawn, which reduces the risk to UK fungal populations.”

At RHS Wisley, local species such as oyster mushrooms, coral tooth fungus, turkey tail, and birch polypore brackets are being cultivated to study their benefits to plants and wildlife. This careful selection helps ensure that beneficial native fungi are used, avoiding the potential risks posed by non-native species.

 

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