There Are Mushrooms Growing at the Base of My Tree — Should I Be Worried?

This is something we are called about regularly, particularly in autumn when fungal fruiting bodies are most visible in gardens across Grange-over-Sands, Kendal, Cartmel and South Lakeland generally. Toadstools appearing at the base of a tree, or bracket fungi growing on the trunk or roots, is something that understandably causes anxiety. This guide explains what you are actually looking at and what to do about it.

What Are the Fungi and What Do They Tell You?

Fungal fruiting bodies, whether they are toadstools, brackets, shelf fungi or any other form, are the reproductive structures of a fungal organism. They appear above ground when the fungus is reproducing, but the fungal organism itself has been present in the tree or soil for a long time before the fruiting bodies become visible. In other words, by the time you see fungi at the base of your tree, whatever process they are part of has usually been under way for some years.

Fungi associated with trees fall into two broad categories. Many fungi form entirely beneficial relationships with tree roots, connecting to the root system and exchanging water and nutrients with the tree in a mutually beneficial arrangement. These mycorrhizal fungi are a normal and healthy part of any tree's life and the toadstools they produce around the base of a tree are a sign of a healthy soil ecosystem, not a problem.

The second category consists of wood-decay fungi, which decompose dead or dying wood within the tree. These are the ones that can be a genuine concern in a garden setting, because significant decay within the structural wood of a tree reduces its structural integrity and, in some cases, its ability to remain safely standing.

The Fungi That Are Genuinely Concerning

Not all wood-decay fungi are cause for equal concern. The key question is where the fungus is growing and what wood it is decaying.

Bracket fungi growing directly on the trunk of a tree, particularly large, firm, woody brackets attached to the main stem, are more likely to indicate significant internal decay than small toadstools at the base. Species such as Ganoderma (Ganoderma applanatum and related species), which produces large brown bracket fungi on a range of broadleaf species, and chicken of the woods (Laetiporus sulphureus), the bright orange and yellow bracket found on oak, cherry and other species, are examples that we take seriously when found on a structural part of the tree.

Toadstools in the lawn around a tree are much more likely to be mycorrhizal fungi or decomposers of buried woody debris in the soil, neither of which are cause for concern about the tree itself. The most common garden toadstool around trees is almost certainly a mycorrhizal or soil decomposer species and is more a sign of a healthy garden ecosystem than a problem.

Honey fungus (Armillaria species), which produces clusters of honey-coloured toadstools at the base of trees in autumn, is a genuine plant pathogen that can infect and kill both trees and shrubs. It spreads through the soil on black root-like structures called rhizomorphs. If you find honey-coloured toadstools growing in clusters at the base of a tree, combined with a tree that is in obvious decline, honey fungus is worth considering as a possible cause and worth having assessed.

What Should You Do?

If you find fungi at the base or on the trunk of a significant tree in your garden, the sensible course of action is to take a photograph of them and give us a call. If you can photograph the fungi from different angles, including any gills or tubes on the underside, and also photograph the tree itself including the base and the crown, this helps us give you an initial view over the phone before visiting.

Do not remove the fungi before we have seen them. The fruiting bodies often appear for only a short period before dying back, and a photograph taken now may be the only record of what is present. If you remove them, it may be difficult to identify what species was present.

We will give you an honest assessment of how concerned you should be and whether a site visit is warranted. In many cases, the fungi are entirely benign. In some cases, they are an early warning sign of something that is worth monitoring or acting on.

Get in Touch

Phone/WhatsApp: 07376804724
Email: enquiries@maxreynoldstreeservices.com

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