Have you noticed one, two, or maybe a collection of mushrooms pop up in your yard recently? These fruiting fungal bodies typically appear after rainfall after a long period without rain. With more than 14,000 species of mushrooms, ranging from beneficial to edible to dangerous, you may be wondering which types are in your yard, and whether they are helping or harming your trees.
Let’s discuss what makes mushrooms appear from the ground, the most common backyard varieties, and when to call a tree care service for an inspection.
What Triggers Mushroom Growth?
Beneath visible mushrooms are underground networks known as mycelium, the root-like structure of fungal cells, or hyphae. These networks enable fungi to absorb nutrients from organic matter in the soil. They are also responsible for the mushroom heads that emerge above ground; when environmental conditions are ideal, the fruiting bodies can grow.
Backyard areas near trees are common areas for mushroom growth because they tend to have all the ideal conditions:
- Decomposing Organic Matter: From fallen leaves to compost and other plant and animal materials, mushrooms break down organic matter and strengthen the health of your soil. As a result, mushrooms have a symbiotic relationship with trees and other plants in their vicinity.
- Increased Moisture: Moisture is needed for mushrooms to appear. Areas of your yard that have poor drainage and get a lot of shade are the most susceptible to mushroom growth.
- Seasonal Changes: A rise in humidity and temperature is also ideal for mushroom growth. You may find an increase in mushrooms in the spring, summer, and early fall, given it’s still warm.
The Safe and Concerning Spots for Mushroom Growth
You’ll know mushrooms are a problem based on their appearance and location in your yard. If you notice mushrooms across the lawn away from your trees, they are likely not a concern, although identification by an arborist will help you know for certain.
On the other hand, mushrooms growing on or close by your tree are likely harmful and require remediation. Look out for fruiting fungal bodies in one of these areas:
- On the tree trunk
- Attached to the bark
- On large, above-ground roots
- On the soil surrounding the base of the tree
Mushroom growth on trees is often a sign of internal damage, root rot, and structural weakness. You may notice additional symptoms of tree health decline, including crumbling bark, leaning, dieback, and other concerns. If dangerous mushroom species go untreated, they can cause tree death over time.
Common Backyard Mushrooms Around Trees
It can be difficult to distinguish the helpful mushrooms from the dangerous ones. After a thorough inspection, a tree care specialist can accurately identify the mushrooms and assess your trees’ health. These are a few common varieties you might find in your backyard:
Mycorrhizal Mushrooms
Mycorrhiza is a symbiotic relationship between a fungus and a plant. Beneath the soil surface, mycorrhizal mushrooms’ hyphae and plant roots exchange nutrients to keep one another healthy. Two common mycorrhiza mushroom species are chanterelle (yellow-orange in color, small, funnel-shaped) and boletes (white stem with a typically a brown capped top with pores underneath).
Decomposer Mushrooms
Also often beneficial to your yard, decomposer mushrooms break down organic matter. Perhaps you’ve seen a curious-looking circle of small white mushrooms in the grass. These are fairy ring mushrooms, and they appear when there is a great amount of wood, leaf litter, and other organic materials in the ground.
Another largely decomposing species, oyster mushrooms are typically found decomposing dead material on trees. They can resemble small seashells protruding from bark and are so effective at breaking down organic material that they can even decompose certain plastics. If you notice these mushrooms growing on a living tree, it’s a sign the tree may be stressed or decaying, and you should have it evaluated by a certified arborist.
Parasitic Mushrooms
Parasitic mushrooms feed on living trees, drawing nutrients from their hosts and often causing significant damage or even death. Unlike true symbiotic fungi, these mushrooms do not benefit the tree—they attack it. Identifying parasitic species early is important for tree health and management.
Honey mushrooms (sometimes known by their scientific name, Armillaria) are highly aggressive and dangerous to trees, developing at the base and sometimes causing root rot. These mushrooms are usually light yellow-brown and feature flat caps. Artist’s conk and other Ganoderma species can also cause decay in trees; these white mushrooms often stick out from the bark itself, and other tree symptoms like bark peeling may also be present.
What to Do About Mushrooms in Your Yard
If a mushroom species in your yard is not parasitic, removal is generally unnecessary. Fruiting bodies—the visible mushrooms—do not harm the tree, nor does removing them affect the fungus itself. Keeping these fungi can actually improve soil quality and support tree health. Removal is purely for aesthetic reasons.
Check for signs of parasitic mushrooms on your nearby trees. If you suspect your mushrooms are attacking your trees, call your local tree care company. An ISA-Certified Arborist can identify the fungal species and the tree’s condition, providing a customized treatment plan. For extensive damage, the tree and any other affected plants may need to be removed in order to eliminate the fungus.
Protect Your Marin County Trees With Treemasters
Mushroom identification can be challenging, especially when several common species share similar characteristics. If you’re concerned about the fruiting bodies in your yard, call Treemasters for a professional assessment.
Since 1987, our tree care team has served Marin County communities on the principles of honesty, integrity, and craftsmanship. Our ISA-Certified Arborists specialize in tree removal, pruning, invasive plant management, and more, providing full-service tree care for yards with a single tree or entire forests.