It’s a perfect fall day — crisp air, blue sky, and brightly colored leaves are starting to drift down onto your emerald green… Hey!!! What is this popping up all over my beautiful lawn?
Mushrooms??? How did they get here? Are they threatening my lawn? Are they killing my trees? Are they poisonous? Will they attract toads, fairies or trolls?
Yes, mushrooms make their appearance in lawns and gardens anytime, but more conspicuously in the fall. That’s when wetter weather and cooler temperatures make ideal conditions for them to emerge. Legends and concerns about mushrooms come and go. But the fungus below the surface is always there.
So mushrooms are fungus, right? And fungal diseases are bad for plants. So mushrooms are bad for plants, right?
Not quite that simple. Mushrooms are indeed the fruiting bodies of various types of fungus. And there are indeed fungal diseases which can damage and kill plants. So mushrooms can trigger our fungal fears, getting blamed for a lot of things they may not be guilty of. We included them in our earlier post: Framed for Murder: Not the Pests You Might Expect.
And they don’t necessarily attract toads, fairies or trolls — unless, of course, you believe…
According to mycologists, the vast majority of fungi are not pathogenic. Most are considered beneficial — in fact, essential — to plant growth and health. Fungi are necessary for decomposing organic matter. They are actually considered a sign of healthy, active soil.
You may have heard of mycorrhizae, which a symbiotic association of fungal mycelium with the roots of vascular plants. It occurs naturally in healthy soil. Because of their beneficial properties, mycorrhizal spores are added as an ingredient in many commercial soil amendments such as G&B Organics® Soil Building Conditioner, a favorite amendment we sell at Swansons.
However, be aware that some mushrooms are indeed poisonous, so any handling or picking requires extreme caution. Read on for further details.
Mushrooms in the Lawn
It can be alarming to wake up and see a cluster (or mysterious “fairy ring”) of large mushrooms sprouting from your lawn, sometimes literally overnight. But these are not likely fungus capable of damaging turfgrass. The fruiting bodies of common lawn diseases such as rust and red thread are tiny in scale, usually appearing as a discoloration of grass blades. Conspicuous mushrooms indicate mycelium feeding on organic matter in the soil.
A cluster of mushrooms could mean the presence of larger sections of wood below the surface, such as a chunk of coarse bark or tree root or branch. They also are more common in shadier or soggier areas.
So if your lawn looked healthy during the growing season, periodic “blooming” of mushrooms is unlikely to indicate a problem. But if they are appearing in more quantity or frequency, and wetness or shade don’t seem to apply, try digging below the surface a bit to see if there are buried branches, old tree roots, or other sources of of host wood. If feasible, replace those woody sections with fresh soil.
Other ways to help reduce the frequency of mushrooms are improving drainage, fertilizing, and reducing watering (especially in the evening or overnight irrigation). Periodically aerating your lawn to help drainage and oxygen circulation can help, as well. Otherwise, let the mushrooms and their remarkable subterranean network do their job. They typically disappear from the surface within a few days or weeks.
In Mulch Beds
As with lawns, mushrooms commonly emerge from organic matter in the mulch, even in your vegetable garden. Not a major concern but breaking up or removing any large chunks of wood in the soil might reduce them.
Mushrooms popping up in mulch beds or lawns are largely a cosmetic problem — if you don’t see them and they’re not harming your plants, you can ignore them. If they often appear on open surfaces of bare mulch or soil, consider planting those areas with low shrubs, perennials, or groundcovers. In addition to benefiting the garden, wildlife, and soil, the plants will hide the mushrooms!
On Trees and Other Plants
Mushrooms can also sprout from dead and decaying trunks, branches, or roots. A healthy tree or shrub may have a branch die off (from being shaded out or other natural causes) and slowly rot away (with mushrooms’ help) while the rest of the tree grows on around it. Sometimes they may pop out from an inconspicuous section of decaying wood on a mostly healthy trunk. The fungus is part of the natural process of decomposing that wood. A healthy tree will often seal off that section so the decay won’t spread to other wood unless the tree has more systemic health issues.
But mushrooms can also be an early sign of die-back that we didn’t notice before. If they are marching up or around the main trunk it may indicate that the tree is dying or already dead. So if you see them, take a close look at the rest of the tree and/or have a certified arborist evaluate it.
Meanwhile, it’s always a good idea to prune off dead branches to redirect growth energy to a tree’s healthy branches.
In Plant Pots
In potted plants, indoor or outdoor, mushrooms can suddenly spring up from the soil or the mulch covering it. Besides growing from any larger pieces of organic matter in the soil, this might suggest that it needs to dry out more between waterings (depending on the species of plant).
Are They Poisonous?
A larger concern is the sudden appearance of unidentified mushrooms if you have small children, pets, or anyone that might be tempted to eat one. Toxic mushrooms can cause severe and long-lasting effects, especially for the smaller members of our family.
To reduce that risk, you can cut or mow down mushrooms when you see them (although it might be a daily task this time of year). If cutting large ones by hand, wear gloves and cut them at their base. Watch out for “puffball” mushrooms which can burst and send out spores. To contain those, wrap them with a bag, cloth, or paper towel before cutting. For any mushrooms you are removing, bag them up and put them in the garbage.
Mushroom Foraging
Are you a mushroom lover? You are not alone. The Pacific Northwest is one of North America’s richest regions for foraging. Our diversity of mushroom species offers an array of nutritional and culinary benefits. But before you do any harvesting or foraging, ALWAYS make or obtain a positive identification to avoid any encounters with toxic species. The best place to start learning what and how to forage is through the Puget Sound Mycological Society.
So let the mushrooms sprout and the toads dance during their brief season. And if they seem to be getting out of hand, feel free to contact us with any questions!