Q: I’ve been noticing lots of mushrooms coming up in my yard. Why are they there? Are they poisonous? Should I get rid of them? If so, how?
A: August is traditionally high season for mushrooms and this year is no exception. Late summer rains have made this a bumper mushroom season, in our yards and everywhere else! In addition to the so-called “toadstools” in our home gardens, hikers have probably noticed plentiful mushrooms of all colors in shady and damp areas on the trails.
To answer your question about why they are in your yard, let’s start with what a simplified idea of what a mushroom is. Mushroom is the word we use to name the visible fruiting structure of fungi that live (usually) underground. So if you have mushrooms, you have some sort of underground fungi. The mushrooms we see in our yards and gardens feed on decaying roots or other organic matter – often from a tree that is long gone. Sometimes fungi travels in the soil in plants you purchase and put in your garden, or spores may come in with a load of mulch.
Both poisonous and non-poisonous mushrooms can make an appearance in your yard. One mushroom that commonly shows up in Colorado yards and gardens (often in “fairy rings”) is Chlorophyllum molybites (green parasol – though it more resembles a traditional, grocery store button mushroom), a highly poisonous type. But we also often have Agaricus campestris (meadow mushroom), an edible mushroom. Of course, never, never, never eat a wild mushroom without having it clearly and positively identified. The Colorado Mycological Society may have lectures and classes in your area, and it is always worth inquiring for help from a local botanic garden.
You cannot eradicate your mushrooms without eradicating the underground fungi of which your mushrooms are the fruiting structures. But those fruiting structures will produce spores which will be spread mostly by wind not too long after the mushrooms are visible. So if you get rid of the mushrooms, you can at least reduce the future number you would have had those spores spread.
If you have children or pets, you may also be concerned about them sampling the mushrooms. Or maybe you just don’t like the idea of running over the mushrooms and chopping them up with your lawn mower (also helping to spread the spores). Though it is kind of fun, kicking a mushroom off to the side does not slow down reproduction. In fact, you may be helping spread the spores! Instead, remove the mushroom by pulling it out of the ground as far down the stem as possible, placing it in a trash bag, and discarding it in your trash.
If you are a hiker, please don’t collect and discard the mushrooms you see on the trail. Instead, enjoy the colorful variety and leave them to reproduce. One of the most colorful native mushrooms we have is showing up in great numbers this year – the fly agaric or sacred mushroom (Amanita muscaria var. flavivolvata). This gorgeous poisonous mushroom emerges from the soil with a creamy membrane over the button. As it grows, the button expands, turning red and leaving small spots of the creamy membrane dotted over it.
If you’d like to learn more, a terrific reference is Mushrooms of Colorado and the Southern Rocky Mountains by Vera Stucky Evenson.
Also, visit the Colorado Mycological Society’s web site at www.cmsweb.org
Text and photos contributed by Carey Harrington, Certified Colorado Gardener