Mushrooms on a tree stump are the fruit of fungi that are rotting the wood, and on a dead stump they mostly mean it is breaking down the way it should. They matter more when they are honey-colored clusters that also show up around living trees, or shelf-like conks on a trunk, and any wild mushroom should be kept away from children and dogs.
What you are looking at
A mushroom is only the visible part of a fungus. The fungus itself is a mass of fine threads running through the wood and soil, and the mushroom is how it spreads spores. Clemson Extension explains that these fungi feed on decaying organic matter such as old roots, stumps and thatch, and that the mushrooms disappear on their own when the weather turns dry or cold, while the fungus carries on unseen. So a crop of mushrooms after a wet week tells you the stump is being eaten from inside. That is how a stump goes away on its own. On a dead stump in the middle of the lawn, most mushrooms are nothing to worry about.
Honey-colored clusters: Armillaria
One kind deserves a closer look. NC State Extension describes Armillaria root rot, also called honey fungus or shoestring root rot, as a disease that decays the roots of many common trees and shrubs. Its mushrooms are yellow to honey-colored clusters that come up in moist weather near the base of a tree and do not last long. Under the bark you may find white fans of fungus between bark and wood, and dark threads like bootlaces. Clemson Extension notes it is widespread on oaks and its mushrooms can appear in clusters along the major roots. The key point: it lives on in old roots, stumps and buried scraps of wood.
Why Armillaria matters for the trees you keep
On a stump, Armillaria is just eating dead wood. The concern is what it does next. NC State Extension says the fungus spreads through roots, can infect new plantings at the same site, and attacks trees weakened by other causes much more easily than vigorous ones. Clemson Extension says no chemical control is effective. Its advice for a diseased tree is to remove it and as much of the root system as possible, and not to replant the site with a susceptible host. If honey-colored clusters appear on a stump and also round the base of a living tree that is thinning or dying back, have that tree looked at and ask your county Extension office to confirm the fungus.
Shelf fungi and conks
Hard, woody brackets sticking out from the side of a stump are conks. One common type, artist's conk, is shelf-like and fan-shaped, tan to gray on top with a bright white underside, and grows a new layer each year. University of Massachusetts Extension says it lives on stumps and downed logs as a decomposer, but on a living tree a conk signals serious internal decay, and an infected tree may fail or uproot in strong wind. So a conk on a stump is fine. The same conk on the trunk of a standing tree near the house, a drive or a play area is a reason to get that tree checked.
Keep them away from dogs and children
Never eat a wild mushroom, and do not let a dog eat one. NC State's College of Veterinary Medicine warns owners never to allow dogs to eat wild mushrooms, even ones that look harmless, and describes the death cap as nearly always fatal to dogs without treatment. Signs of poisoning can start six to twelve hours later, then seem to ease before liver failure sets in, which fools owners. If you think your dog ate one, get to a vet at once. If a child eats one, call Poison Control at 1-800-222-1222. The college also advises picking mushrooms out of the yard promptly and watching dogs in warm, damp weather.
Will removing the stump stop them?
Picking mushrooms does nothing to the fungus. It is in the wood, not the cap. Grinding the stump takes the biggest block of food away, turning it into chips below grade, and that usually cuts down the crop in that spot. It does not end it, because the roots are still down there rotting, and Clemson notes these fungi also feed on old roots. You may see a flush of mushrooms on the grindings or in the lawn over the roots for a season or two. In a lawn, that is the last of the tree being recycled. Where Armillaria is the fungus and the spot is to be replanted, full stump removal gets more of the infected wood out.
Fairy rings where an old tree stood
Sometimes mushrooms come up in an arc or ring in the lawn, often where buried wood lies. Clemson Extension calls these fairy rings, notes that most mushrooms do not damage a lawn, and says fairy ring fungi are not plant parasites. They can still cause trouble, though, because their threads can make the soil shed water, leaving rings of dark green or dry, dying grass. Clemson suggests patience, deep watering over several days and core aeration, or replacing the affected soil. If you are planning to plant where the stump was, read replanting a tree in the same spot first.
Common Questions
Are mushrooms on a stump a sign that my other trees are sick?
Usually not. Most stump mushrooms are fungi rotting dead wood. The one to watch is Armillaria: honey-colored clusters that can also appear round the base of living trees. If a nearby tree is thinning, dying back or shows mushrooms at its base, ask your county Extension office to identify the fungus and look at the tree.
Will grinding a stump stop mushrooms from coming back?
It cuts them down, because it removes the stump, the largest source of food for the fungus. It will not stop them entirely, since the roots stay in the soil and rot for years, and fungi feed on those too. Expect a few in wet spells for a season or two, then fewer as the wood runs out.
What should I do if my dog eats a mushroom from the yard?
Treat it as urgent and get to a vet straight away, without waiting for symptoms. NC State's veterinary college says signs can take six to twelve hours to show and can seem to improve before serious liver damage appears. Take a sample of the mushroom with you in a paper bag if you can do so safely.
What to Do Next
If the stump the mushrooms live on is in the way, grinding it takes away most of their food. Call (828) 574-4474, or send a picture of the stump beside something for scale along with your town, for a free price. See stump grinding for how the job runs.