What to Do If You Find Fungi on Your Tree
As autumn approaches and the air turns damp, fungi start to emerge, and trees can be one of their favourite habitats. But what does it mean if you find fungi growing on your tree? Is it harmful? Should you be concerned? Here’s a practical guide on what to do if you spot fungi on a tree.
1. Don't Panic – But Don't Ignore It Either
Fungi growing on or around a tree can be a natural part of its ecosystem, but in some cases, they may signal underlying health or structural problems. Certain types of fungi are decomposers that break down dead wood, and their presence may indicate decay inside the tree.
2. What Is Tree Fungi?
Fungi are complex organisms that play a vital role in natural ecosystems by breaking down organic material – including wood. When we talk about "tree fungi," we're often referring to the visible fruiting body, such as a bracket or mushroom, that appears on the trunk, roots, or base of a tree. However, this is just the reproductive part of the organism.
The main body of the fungus, known as the mycelium, lives within the tree itself – typically in the heartwood, sapwood, or root system. It's composed of a network of microscopic threads (hyphae) that spread through the wood, gradually digesting it from the inside. When conditions are right – often in autumn – the fungus produces fruiting bodies to release spores and continue its life cycle.
So while the bracket may be the only visible sign, it usually indicates a much more extensive fungal presence inside the tree.
3. Types of Fungi to Look Out For
Some common types of fungi associated with decay in trees include:
Ganoderma (a bracket fungus that can indicate significant basal decay)
Meripilus giganteus (often found on beech, signalling root decay)
Armillaria (honey fungus, which can affect both roots and base)
While not all fungi are harmful, it’s vital to identify them correctly.
4. Why It Matters
Fungi like these can compromise a tree’s structural integrity, increasing the risk of limb failure or collapse. Many fungi achieve this by breaking down the structural wood fibres within the tree – targeting either cellulose, lignin, or both – which leads to a loss of strength in the stem, roots, or branches. This internal decay often progresses silently, with little external sign beyond the fruiting bodies, making regular inspection especially important.
This is particularly concerning if the tree is in a high-use area – near homes, public footpaths, playgrounds, or roads – where any failure could pose a significant safety risk.
5. Call in a Qualified Arboriculturist
If you discover fungi on your tree, the best course of action is to contact a qualified arboriculturist. At Canopy IQ, we can carry out a detailed Tree Condition Survey to:
Identify the species of fungi present
Assess the health and structural integrity of the tree
Recommend any necessary tree work, in accordance with BS 3998:2010 Tree Work – Recommendations
Advise whether the risk is tolerable or if remedial action is needed
6. Managing the Risk
In line with the National Tree Safety Group’s guidance, tree risk should be managed in a reasonable and proportionate way. Most trees with fungi don’t need to be felled – in many cases, pruning or reducing target use (e.g., fencing off an area) is enough to reduce the risk to an acceptable level.
7. Record and Monitor
Even if immediate action isn’t necessary, it’s important to monitor the tree over time. Fungal fruiting bodies can be seasonal, but underlying decay may progress. A regular inspection cycle can help you manage this proactively.
Need Expert Advice?
If you've found fungi on your tree and want peace of mind, we’re here to help. We provide clear, expert advice backed by the latest arboricultural standards. Book a Tree Condition Survey with Canopy IQ today.
