Late summer and early fall are prime mushroom season in Missouri. After periods of rain and warm temperatures, homeowners often notice mushrooms at the base of trees and wonder if they should be concerned.
Fungus around a tree can indicate root issues, decay, and concerns about tree stability, but not every mushroom is a threat. Understanding the difference can help prevent costly tree failures and identify problems before they become hazardous.
Why Mushrooms Grow Around Trees
Mushrooms are nature’s recyclers, with most fungal activity happening underground. They are fruiting bodies that feed on dead organic material in the soil, such as old, buried wood, mulch, or decaying tree roots. Combined with Missouri’s rainy and humid summers, this creates ideal conditions for mushrooms to grow around trees.
Peak mushroom season is typically late August through October.
When Mushrooms Are Harmless and When They're a Warning Sign
A mushroom’s location is often more important than what species of mushroom is in your yard. Most mushrooms in mulch and located away from the trunk are harmless. Here’s when you should be concerned about seeing tree fungus:
Repeated mushroom growth
Mushrooms emerging from tree roots
Mushrooms around the tree trunk or attached to the trunk
Fungal conks on trees
Mushrooms appearing after storms
Common Missouri Tree Fungus
If you notice fungi on or near your trees, don’t try to identify them solely by appearance. A professional evaluation focuses on what the fungus indicates about the tree’s health, not which species it is. Here are some common Missouri tree fungi and what they could mean:
Fungus | What Homeowners Notice | What It May Mean |
Armillaria (Honey Fungus) | Honey-colored mushrooms near roots | Root rot and decline |
Ganoderma | Shelf-like conks on trunk | Internal trunk decay |
Mushrooms in mulch | Small mushrooms after rain | Usually harmless decomposition |
Other Signs Your Tree May Have Root Health Problems
Mushrooms growing around a tree are often one symptom of a larger issue. If you see fungus around a tree, check for these other signs of root health issues and tree decay:
Thinning canopy
Dead branches
Unseasonal fall color
Leaning
Exposed roots
Reduced leaf size
Why Missouri Weather Makes Mushrooms More Common
Missouri’s climate typically includes heavy rainfall, humid summers, and warm nights. These weather conditions, combined with the clay soils in St. Louis and the surrounding metro area, encourage fungal growth.
What Should You Do If Mushrooms Appear Around Your Tree?
If you notice mushrooms around your tree, don’t act hastily. Photograph the mushroom, note its location, monitor changes to your canopy, and schedule an inspection with a certified arborist if growth continues. Avoid these common mistakes:
Removing mushrooms and assuming the problem is solved
Applying fungicide
Cutting roots
Ignoring shelf fungi
Mushrooms can be harmless, but they can also be one of the first visible signs of root decay or structural problems hidden below ground. If you've noticed mushrooms growing around the base of your tree or attached to the trunk, a professional evaluation by a certified arborist can determine whether they're simply decomposing organic matter or indicating a more serious issue.
Schedule a tree inspection with your local Davey certified arborist in Missouri to assess your tree's health and catch hidden problems before they become safety hazards
FAQ Section: Missouri Homeowners' Questions About Tree Mushrooms
Not always. Many mushrooms simply grow on decaying organic matter. However, mushrooms growing from roots or the trunk can indicate root rot or internal decay.
Removing the mushrooms won't eliminate the fungus beneath the soil or in the wood. If mushrooms keep returning, it's a good idea to have the tree inspected.
Typical mushrooms grow from the ground and often disappear within days. Shelf fungi (conks) grow directly on the trunk or roots and are more commonly associated with internal wood decay.
Yes. Missouri's warm, wet weather creates ideal conditions for fungal fruiting, especially in late summer and early fall.
If mushrooms appear repeatedly in the same location, grow from the trunk or exposed roots, or are accompanied by dead branches, canopy thinning, leaning, or peeling bark, schedule an inspection with a certified arborist.
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