The short version
- Mushrooms, brackets, and conks growing from a tree can be fruiting bodies of wood decay fungi. UGA Extension says conks or mushrooms on the trunk or root flare mean the tree is in an advanced stage of decay.
- Growth at the base can point to root rot; growth higher up, to trunk rot. Moss and lichen on bark do not hurt trees.
- There is no chemical cure for trunk and limb rot, per University of Maryland Extension.
- HomeGuide puts a national arborist inspection at $100 to $250.
Roanoke Tree Removal is a local referral service: we pass your request to an independent, local tree crew. We are not a contractor or a government office, and this page is general information, not legal advice.
What a mushroom on the trunk tells you
University of Maryland Extension calls these growths basidiocarps, the fruiting bodies of decay fungi. Some are soft and come back each year; others are hard shelves that add a layer each year as the rot spreads. Colors run from white, yellow, and orange to brown or pale gray.
UC IPM says decay is often invisible from outside, except at wounds, cavities, or where the fungus fruits. UGA Extension says it takes years of growth inside the wood before conks or mushrooms appear. If you see them on the trunk or root flare, the tree is in an advanced stage of decay and there is a concern it could fail. For other warning signs, see how to tell if a tree is dying.
Base, trunk or branch: why location matters
Maryland Extension says fruiting bodies near ground level can mean either root rot or trunk rot, so look for other symptoms. Trunk rot often shows nothing else, because heartwood does not carry sap. Root rot often brings dieback and other symptoms, since it disrupts the flow of sap. The Virginia Department of Forestry says simply that mushrooms can indicate root decay.
Fungus at a branch stub or old wound shows where it got in. UC IPM says most decay starts when spores land on exposed wood: broken limbs, pruning cuts, damage from machinery or construction, sunburn, lightning, ice, or insect holes.
Common decay fungi and how to spot them
| Fungus | What to look for | Source |
|---|---|---|
| Artist's conk (Ganoderma applanatum) | Hard, fan-shaped shelf with a dull brown top and bright white underside. UMass cites a 1954 study in which one conk marked a decay column about 4 to 6 feet above and below it; UC IPM says columns can reach 15 feet. Hosts include maple, beech, and oak. | UMass Extension, Checked Oct 16, 2026 UC IPM, Checked Oct 16, 2026 |
| Chicken of the woods, sulfur fungus (Laetiporus) | Soft, sulfur-yellow to bright orange shelves on ash, beech, cherry, maple, oak, and tulip tree. A brown heart rot that is well along before shelves appear. | UMD Extension, Checked Oct 16, 2026 UC IPM, Checked Oct 16, 2026 |
| Honey mushroom (Armillaria) | Clusters of yellowish mushrooms at the base, often after rain, with white or cream sheets of fungus under the bark near the soil line. A root and butt rot. | UC IPM, Checked Oct 16, 2026 UMD Extension, Checked Oct 16, 2026 |
| Oyster mushroom (Pleurotus) | Shelf-like clusters with gills running down the stalk. Can mark heart rot running about 10 feet each way. | UC IPM, Checked Oct 16, 2026 |
| Turkey tail (Trametes) | Tough, leathery brackets with banded rings, often on dead or wounded parts of living hardwoods and on cut wood. A white rot. | UC IPM, Checked Oct 16, 2026 UMD Extension, Checked Oct 16, 2026 |
The decay-column figures are each source's own estimate, not a measurement of your tree. Do not eat wild mushrooms based on a table like this one.
White rot and brown rot
UGA Extension sorts decay fungi into two broad groups. White-rot fungi break down lignin first, then cellulose, leaving wood that is soft, spongy, or stringy and white or yellow. Brown-rot fungi go after cellulose, leaving wood brown and brittle; it cracks into cubes. UGA says it is usually a root and buttress rot caused by a white-rot fungus that brings hardwood trees down.
Either way the wood loses strength fast. UC IPM says a 10 percent loss in wood weight can mean a 70 to 90 percent loss in strength.
Lichen, moss and mold are different
The Virginia Tech Tree Steward Manual says the plants most often seen living on Virginia trees are mosses and lichens, and that they do not damage the trees they grow on. The same manual lists mold, mildew, mushrooms, and conks as fungal structures you can see, and its table of signs of tree problems includes mold growth and fungal bodies. Moss or lichen alone on a healthy tree is not a reason to remove it.
Can a tree with fungus be saved?
The fungus cannot be removed. Maryland Extension says there are no chemical cures for trunk and limb rots. UMass Extension says eradicating artist's conk is not possible and fungicides do little against wood decay fungi, because the fungus is deep in the heartwood.
That does not mean every tree with a mushroom must come down today. UMass says that early in decay the wood keeps much of its stiffness, and the University of Kentucky notes that not every wound leads to decay, because trees often wall off injured wood. Safety depends on how much sound wood is left and what is under the tree. UMass also warns that infected trees can snap or uproot in strong wind without any earlier dieback.
How an arborist checks the decay
Maryland Extension says to consult a certified arborist to judge how far the rot goes once fruiting bodies show up. UMass names resistance drilling and sonic tomography for measuring decay in the lower trunk. UGA notes these find cavities and shell thickness, but spongy wood is harder to measure. Trees with known decay that stay standing should be inspected each year, according to UGA.
Virginia Cooperative Extension's tree evaluation form lists mushrooms on or at the base of the tree and conks or fungal growths on the trunk as signs to record. Photos of the growth, the base, and any cracks help. You can find an ISA Certified Arborist through the ISA directory, or book an arborist risk assessment.
What an arborist visit costs (national)
| Item (national) | Published figure | Source |
|---|---|---|
| Tree inspection or risk assessment | $100 – $250 | HomeGuide, Checked Oct 16, 2026 |
| Single-tree consultation and report | $150 – $450 | HomeGuide, Checked Oct 16, 2026 |
| Arborist hourly rate | $100 – $250 per hour | HomeGuide, Checked Oct 16, 2026 |
| Tree cabling | $200 – $350 per tree | HomeGuide, Checked Oct 16, 2026 |
| Tree pruning | $200 – $800 per tree | HomeGuide, Checked Oct 16, 2026 |
| Tree removal | $300 – $2,000 per tree | HomeGuide, Checked Oct 16, 2026 |
HomeGuide figures are national, not Roanoke quotes. For removal pricing in more detail, see dead tree removal cost and tree removal cost by size.
Keeping decay out of healthy trees
Most decay starts at a wound, so prevention is mostly about wounds. The University of Kentucky lists the usual causes: mower and trimmer hits, pruning stubs, construction digging, vehicles, wire left on a trunk, herbicides, animals, boring insects, and storms. The Virginia Tech Tree Steward Manual says a 2 to 3 inch layer of mulch under the tree, kept a few inches off the trunk, keeps mowers and trimmers away; see mulch volcanoes for how much is too much.
UC IPM says to prune just outside the branch bark ridge, leave no stubs, and skip wound dressings, which do not prevent decay and in some cases may speed it. Maryland Extension suggests pruning during the dormant season, since these fungi release spores through the growing season, especially in fall. For timing in Virginia, see when to prune trees in Virginia.
Fungus on a tree near your house?
Call (540) 904-1819 or use the form. Tell us where the growth is and what the tree could fall on. We will pass your request to an independent local tree crew. If the trunk is cracked or leaning, see hazard tree removal and split tree trunk.
Common questions
What does a mushroom on a tree trunk mean?
It is the fruiting body of a wood decay fungus. UGA Extension says conks or mushrooms on the trunk or root flare mean the tree is in an advanced stage of decay.
Can a tree with fungus be saved?
The decay cannot be cured. Maryland Extension says there are no chemical cures for trunk and limb rot. Whether the tree can stay depends on how much sound wood is left and what it could hit. An arborist can check for cavities and shell thickness, though UGA notes spongy decay is hard to measure.
Will fungus kill a tree?
UGA Extension says a tree infected with wood decay fungi will fail at some point; the question is when. UC IPM says the varnish fungus can kill its host over 3 to 5 years.
Can I spray a tree to get rid of fungus?
No. UMass Extension says fungicides are of little value against wood decay fungi because they are inside the heartwood.
Is lichen on a tree trunk bad?
No. The Virginia Tech Tree Steward Manual says mosses and lichens do not damage the trees they grow on.
How much does an arborist inspection cost?
HomeGuide's national range is $100 to $250 for an inspection or risk assessment, and $150 to $450 for a single-tree consultation and report.
Sources
- UC Statewide IPM Program, Pest Notes: Wood Decay Fungi in Landscape Trees (Pub. 74109, updated Aug 2019) (Checked Oct 16, 2026)
- University of Maryland Extension, Wood Rots and Decay on Trees and Shrubs (updated Feb 28, 2023) (Checked Oct 16, 2026)
- UMass Extension, Root and Trunk Rot caused by Ganoderma applanatum, Artist's Conk (updated Apr 5, 2024) (Checked Oct 16, 2026)
- UGA Extension Bartow County, Mushrooms on Trees (July 24, 2019) (Checked Oct 16, 2026)
- Virginia Tech, Tree Steward Manual, Chapter 10: Problems of Trees (Checked Oct 16, 2026)
- Virginia Cooperative Extension, How to Evaluate a Tree (SPES-313P, PDF) (Checked Oct 16, 2026)
- Virginia Department of Forestry, Forest Health: Scout It Out! (July 30, 2021) (Checked Oct 16, 2026)
- University of Kentucky Extension, Tree Wounds: Invitations to Wood Decay Fungi (PPFS-OR-W-01, Sept 2015, PDF) (Checked Oct 16, 2026)
- HomeGuide, arborist cost (national, Feb 4, 2026) (Checked Oct 16, 2026)
- International Society of Arboriculture, Find an Arborist (Checked Oct 16, 2026)