There are mushrooms growing at the base of my tree. Should I be worried?

Mushrooms at the base of a tree can be a serious warning sign, but not all fungi are created equal. The mushrooms you see are the fruiting bodies — the reproductive structures — of a much larger fungal organism living inside or around your tree's root system. The real question is: which fungus is it, and what is it feeding on?

High-concern fungi (these indicate internal decay):

• Honey mushrooms (Armillaria) — clusters of honey-colored mushrooms at the base, often with white mycelial fans under the bark. This is one of the most destructive root rot pathogens.
• Artist's conk (Ganoderma applanatum) — large, woody, shelf-like brackets with a white underside you can draw on. Indicates advanced heartwood decay.
• Chicken of the woods (Laetiporus) — bright orange and yellow shelves. Beautiful but feeding on heartwood.
• Giant polypore (Meripilus giganteus) — large rosettes of brown, overlapping fan-shaped brackets at the base. Associated with root and butt rot.

Lower-concern fungi:

• Mycorrhizal mushrooms — many mushrooms near trees are beneficial partners that help the tree absorb nutrients and water. These include boletes, chanterelles, and many small brown mushrooms growing in the soil (not on the wood itself).

What to do:

1. Photograph the mushrooms from multiple angles, including the underside showing gills or pores.
2. Note the location — growing directly from wood/roots vs. from soil nearby. Fungi growing from the wood itself are more concerning.
3. Consult a certified arborist for identification and a tree risk assessment.
4. Do NOT remove the mushrooms thinking it solves the problem — they're just the fruiting bodies. The fungal network inside the tree can be extensive.
5. If a decay-causing fungus is confirmed, a resistograph or sonic tomography test can measure how much sound wood remains.

Learn more in our Fungal Growth on Trees guide and Is My Tree Dangerous?.