If you are a mushroom fan you have probably heard of the Garden Giant mushroom (Stropharia rugoso-annulata). Or if you heard mycologist, Paul Stamets speak or have read his book, Mycelium Running, you may also know a bit about this species’ role in fungal bioremediation. If you engaged in Garden Giant companion planting last season, then the mycelium is already hard at work helping to protect and groom your garden.
For those unfamiliar with outdoor mushroom cultivation, companion planting with the Garden Giant mushroom is easy. This rich edible mushroom is available from mushroom supply companies as spawn. Garden Giant outdoor mushroom spawn comes as a bag of sterilized wood chips that are infused with the white cobweb-like tissue of the mushroom, called mycelium. This mushroom spawn is simply mixed into the mulch layer in your garden to establish a mushroom bed.
Among the many fascinating features of this species is a tendency toward tenacious growth on unbelievably diverse materials. From corn stalks to straw, from conifer duff to hardwood chips, the Garden Giant can digest them all. It can accomplish this feat primarily because of its unique suite of leaf litter decomposing enzymes. The Garden Giant is unique in that it can grow as either a primary or secondary decomposer. This trait allows it to interface readily between the topsoil and mulch layer in your garden. As spring temperatures warm and your Garden Giant wakes up, it is actively digesting and remobilizing last season’s refuse into this summer’s fertility.
These benefits may be obvious for the observant gardener, but what may be less obvious is the Garden Giant’s guardianship of the microscopic microbial landscape. In the late 1980s, Fungi Perfecti founder and mycologist Paul Stamets determined that a serendipitously placed Garden Giant mushroom was responsible for reducing bacteria runoff from upland pasture at his western Washington, US farm. Following this initial inspiration, several years of small experiments, an EPA stormwater management innovative research grant, and some large-scale field trials, have documented that the mycelium of the Garden Giant mushroom can improve the ability of mulch to filter and remove E. coli. Further, Stropharia rugoso-annulata mycelium produces spiky crystalline-like spherical structures called acanthocytes. In 2005, researchers at Yunnan University and Kunming University of Science and Technology in China documented that acanthocytes act as nematode-destroying microscopic barbs that eviscerate garden pests as they pass by the mycelium in the soil (Hong et al., 2006).
The Garden Giant is a delicious and adaptable mushroom and will thrive in most locations. FMI go to www.fungi.com
Alex Taylor is assistant researcher at Fungi Perfecti.