Do Not Fear the Fungus Among-us — Mushroom Advice from a ‘Fun Gal’!

Now that the clouds have parted, we are finally experiencing a break in this years’ spring monsoon season!  Lots of soil moisture and warm temperatures will result in several things, including the emergence of mushrooms popping through the soil surface.  The Master Gardener diagnostic desk always receives a lot of phone calls regarding mushroom identification and control practices so, it seemed timely to address some of the frequently asked questions in a garden blog post.

Here are 4 things to know about mushrooms in the garden.

1. Do not attempt to identify and consume mushrooms unless you are extremely comfortable doing so. Mushrooms can be extraordinarily difficult to identify (we do not attempt to do so here at the Extension office) and even some of the choice edible types have poisonous look-a-likes. No kidding, you can get out of your league VERY quickly and there can be enormous consequences for doing so.  As an alternative, look-up local mushroom societies and consult with those that have many years of experience identifying mushrooms. This can be a fun social event too!  At times, I like to join my friends at the Utah Mushroom Society on their monthly ‘Mushroom Soirees’. Mushroom identification experts take newbies like me out to collect and CORRECTLY identify my bounty. Check-out the Utah Mushroom Societies Facebook page for more details Utah Mushroom Society Facebook.
2. The bulk majority of the fungus organism (mycelium) is located underground. Fungus produces hyphae (think roots of plants) that probe and explore the soil or their host.  The mushroom cap you see is the reproductive structure of the fungus (think flowers of plants) – it is within the caps that spores (think seeds of plants) are produced for reproduction.  So by stomping on a mushroom cap, you are not killing the organism residing in the soil below.
3. Many types of fungus are beneficial. A question for those savvy gardeners out there, have you ever heard of mycorrhizae?  Definitely a good thing to have in your soil, right?  Absolutely!  Mycorrhizae are beneficial partnerships between fungus and host plants. Some mushrooms are saprophytes meaning they live off dead or decaying organic matter. In this way, they are important recyclers of nutrients to a form that is available for plant uptake.  If you are concerned about children or animals consuming poisonous mushroom caps, pick and dispose of them as they emerge.  Be sure to wear gloves or wash your hands after doing so.
4. It is not uncommon to see rings of mushrooms develop around a tree or shrub that was previously cut down. I am going to pull from my friend, Michael Piep, a mushroom expert, from the USU Herbarium for more information on fairy rings – take it away Michael!

“The name fairy ring comes from an old folk-tale. People once believed that mushrooms growing in a circle followed the path made by fairies dancing in a ring. Fairy rings are found in open grassy places and in forests.

In grass, the best known fairy ring fungus has the scientific name Marasmius oreades. The body of this fungus, its mycelium, is underground. It grows outward in a circle. As it grows, the mycelium uses up all of the nutrients in the soil, starving the grass. This is the reason a fairy ring has dead grass over the growing edge of the mycelium. Umbrella-shaped fruiting bodies, called mushrooms, spring up from just behind the outer edge of the mycelium.

Large rings are created when the older mycelium in the center finally exhausts the soil nutrients and dies. On the death of the central mycelium, the nutrients are returned to the soil and grass can grow again.

The living edge of the mycelium continues to grow outward. As it grows, it secretes chemicals into the ground ahead. These chemicals break down the organic matter, releasing nutrients so that the mycelium will have food when it reaches this area. For a brief time, the grass at the outer edge of the ring also benefits. The extra nutrients make the grass darker green, taller, and thicker than the rest of the lawn or pasture. This lush grass dies when the mycelium grows under it and steals the nutrients.

Fairy rings made by fungi like Marasmius oreades are called “free” rings. They will continue to grow outward until a barrier is reached. Sometimes the barrier is another fairy ring! Rings can grow into each other’s territory and die as each reaches the other’s “dead zone.”

If there are no barriers, free rings can grow outward at up to 8 inches (20 cm) per year. They can reach a diameter of over 30 feet (10 m). One ring formed in France by the fungus Clitocybe geotropa is almost a half mile (600 m) in diameter. This ring is thought to be 700 years old.

Mycorrhizal fungi, which live in symbiotic partnership with trees, also form fairy rings. Their rings are called “tethered” rings. A tether is like a leash. The fungus and its mycorrhizal partner tree need each other to survive. The mycelium of these fungi always remains joined to the tree’s roots. Roots are the “tether” that keeps the fairy rings of mycorrhizal fungi from growing too far from their tree.” — (Fun Facts About Fungi (TM))