Bracket fungus growing on your tree trunk is more than just an eyesore — it's a warning sign that something serious is happening inside the tree. While you can physically remove the visible fruiting bodies, this won't cure the underlying problem, and in many cases the tree may already be structurally compromised. Here's what you need to know to handle it safely and sensibly.
What Is Bracket Fungus?
Bracket fungus (also called shelf fungus or conk) is the visible fruiting body of a wood-decay fungus living inside your tree. Common types found on NZ trees include species of Ganoderma, Trametes, and Phellinus, among others. The bracket itself — that hard, shelf-like growth protruding from the trunk or roots — is just the tip of the iceberg. The fungal mycelium has typically been colonising the heartwood or sapwood for years before you ever see it.
Because NZ's warm, humid climate (especially in the North Island and coastal areas) creates ideal conditions for fungal growth, bracket fungi are a relatively common problem for homeowners with mature trees.
What Does It Mean for Your Tree?
The presence of bracket fungus almost always indicates internal wood decay. Depending on the species of fungus and how long it has been present, the tree may have:
- Significant loss of structural strength in the trunk or major roots
- Hollow sections that aren't visible from the outside
- Root rot, which can cause the whole tree to lean or topple without warning
A tree with advanced decay can fail suddenly, especially during high winds — a real risk in many parts of New Zealand. This makes assessing the tree's safety a priority, not just an aesthetic concern.
Can You Simply Remove the Brackets?
Yes, you can physically knock or cut off the bracket fruiting bodies, but it's important to understand what this does and doesn't achieve:
- What it does: Removes the spore-producing structure, which may slightly reduce spread to nearby trees or timber structures.
- What it doesn't do: Eliminate the fungus living inside the tree, reverse any decay, or make the tree safe.
If you do remove brackets yourself, wear gloves and a dust mask, as the spores can be an irritant. Bag and dispose of the brackets in your general rubbish — don't compost them or leave them near other trees or timber.
There is no effective chemical treatment that can be applied to cure an established internal wood-decay fungus in a living tree. Products marketed for this purpose have little to no proven efficacy once the fungus is well established inside the wood.
Assessing the Risk: What to Look For
Before deciding on a course of action, do a careful visual inspection. Look for:
- Multiple brackets or brackets near the base or roots (higher risk)
- Leaning of the trunk that wasn't there before
- Cracks or splits in the bark near the brackets
- Soft, spongy, or hollow-sounding wood when you tap the trunk
- Dead or thinning canopy above the affected area
- Mushrooms or fungal growth at the base or around the roots
Any of these signs alongside bracket fungus should be treated as urgent. The tree may pose a risk to people, property, or neighbouring trees.
What You Can Do Yourself
- Remove visible brackets carefully using a hand saw, chisel, or sturdy knife, then bag and bin them.
- Keep the area around the base of the tree clear of mulch piled against the trunk, as this retains moisture and encourages fungal spread.
- Avoid wounding the tree further with lawnmowers or weed eaters near the base — fresh wounds are entry points for fungal spores.
- Water and fertilise the tree appropriately to support its general health, though this won't reverse existing decay.
- Monitor the tree regularly for new bracket growth or changes in the canopy.
When to Call a Professional
This is a situation where getting a qualified arborist involved early can save you significant cost and risk down the track. You should call a professional if:
- Brackets are present at or near the base of the trunk or on major roots
- The tree is large, mature, or located near your house, fences, power lines, or areas where people gather
- You notice any leaning, cracking, or canopy dieback
- You're unsure of the extent of the decay
- You're considering removing the tree entirely
A qualified arborist can carry out a risk assessment, and may use tools such as a mallet tap test or, in some cases, specialist equipment to gauge the extent of internal decay. They can advise whether the tree can be retained safely (sometimes with crown reduction to reduce wind loading) or whether removal is the safest option.
Tree removal can be complex and dangerous work, particularly for large trees or those near structures. In some cases, resource consent or a permit from your local council may be required before removing a tree, especially if it is protected under a District Plan or located in a notable tree register. Always check with your local council before felling.
You can find qualified local arborists on tradedirectory.co.nz. Look for members of the New Zealand Arboricultural Association (NZAA) or those holding a relevant trade qualification.
A Note on Safety
Never attempt to climb or work at height in a tree showing signs of structural decay — the wood may fail without warning. Leave any aerial work strictly to trained professionals with appropriate equipment and insurance.
For guidance on tree hazards and property safety, WorkSafe NZ has useful resources on managing risks from falling trees and branches.
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