What does bracket fungus on a tree trunk mean?

By the time a bracket appears, the fungus has been decaying wood inside the tree for a long time, often many years. That is the single most useful thing to understand: the bracket is a symptom of an established internal process, not a new infection you have caught early. Knocking it off changes nothing about the decay and throws away the only clue you had.

What you'll need

• A camera
• A ruler for scale in photographs (optional)

Step by step

1. Photograph it before anything else.Several angles, with something for scale, showing exactly where it is on the tree and how it attaches. This is what an arboriculturist needs and it is often the only way to identify the fungus, since brackets change through the season.
2. Note the position, because that is what matters most.At the base or on the root buttresses: potentially serious, because that is where the whole tree's load is carried. On the lower trunk: significant. High in the crown on a dead branch: usually much less important, and often just a recycler doing its job.
3. Note whether it is on living or dead wood.Many bracket fungi are saprophytes that only break down wood that is already dead, which is a normal and useful ecological process. Others are parasites and pathogens active in living structural wood, and those are the ones that matter.
4. Do not remove the bracket.It is the fruiting body — the mushroom, in effect — and the fungus itself is the network inside the wood. Removing it does nothing to the decay and destroys the evidence needed to identify what you are dealing with.
5. Look for the other signs at the same time.Cracked or heaved soil at the base, a new lean, cavities, dead bark, crown dieback and sawdust. A bracket plus any of those is a much stronger signal than a bracket alone.
6. Think about what is underneath the tree.A decaying tree in a corner of a large garden away from everything is a wildlife asset. The same tree over a house, a road, a pavement or a play area is a risk that needs managing.
7. Get an arboriculturist to assess it.They will identify the fungus, judge how much sound wood remains, and where necessary use decay detection equipment. The outcome is often monitoring or crown reduction rather than felling.
8. Check protection status before any work is proposed.A TPO or Conservation Area status applies to a decaying tree exactly as to a healthy one. Councils consider well-evidenced applications, and an arboricultural report is the evidence.
9. Keep a record and re-inspect.Photograph the same spot annually. The rate of change matters — a tree that has carried the same bracket for ten years with no other symptoms is a different case from one that has declined visibly in two.

Tips

• Some of these fungi are among the most important organisms in a woodland ecosystem. If the tree threatens nothing, retaining it as standing deadwood, perhaps reduced to a safe monolith, is a genuinely good outcome.
• Brackets on a stump or on a long-dead branch are just decomposition. That is what fungi are for.
• Do not attempt to identify a bracket from a website and then make a felling decision on it. Species identification from a photograph is unreliable and the consequences run both ways.

Common mistakes

• Knocking the bracket off to get rid of it — The fungus lives inside the wood. Removing the fruiting body is like picking an apple to kill an apple tree, and it removes the diagnostic evidence.
• Assuming any bracket means the tree must come down — Many are harmless saprophytes on dead wood, and trees compartmentalise decay effectively. Assessment, not assumption.
• Assuming a bracket high in the crown is as serious as one at the base — Structural failure risk is concentrated where the load is. Base and lower trunk decay is the dangerous kind.
• Painting or sealing the area — Wound sealants do not stop internal decay and are no longer recommended for tree wounds generally.

Questions people ask