Fungus on Tree Roots Above Ground in Flint, MI?

Fall is the time of year a lot of different fungal species start growing fruiting bodies. These may be mushrooms growing from the bark of a tree or plate-like fungi growing on the tree or on the roots near the trunk.

Why Do Fungi Feed on Trees?

It all comes down to sugar. Every living organism needs carbon, hydrogen, and oxygen for energy and structural building. When we consume carbohydrates, our bodies break them down to extract these essential elements for fuel and construction. Even your car operates on carbon, hydrogen, and oxygen in the form of hydrocarbons. Similarly, trees are made up of carbon, water, and oxygen, organized into complex molecules to form structural wood. The tree's skeleton consists of cellulose and lignin, the latter providing strength and stability to the tree.

How Do Fungi Feed on Trees?

Fungi use enzymes to break down complex molecules like cellulose and lignin, rearranging them to create their own structures, which are long, threadlike networks called mycelium. When mature, basidiomycete fungi produce fruiting bodies (mushrooms) that contain spores. These spores are released into the air when temperature and humidity are right for reproduction. The mushroom is a small part of the entire fungal organism, similar to how an apple is only a small part of the whole tree.

Can Trees Defend Themselves Against Fungi?

Yes, trees have strong defenses against many fungi, provided they are healthy. The bark acts as the first barrier, preventing fungi from entering. However, damage to the trunk from storms, machinery, or improper climbing methods (such as tree climbing spikes) can create openings for fungi. Damage to branches, improper pruning, or root disruption during construction also serve as potential entry points. If the tree is in good health, it uses compartmentalization to wall off the fungi from spreading inside the tree.

What Type of Fungi Is Growing on My Tree?

If you're seeing mushrooms on your tree or sprouting near the base, they’re most likely part of the basidiomycetes group of fungi, also called "club fungi." These fungi produce spores on club-like structures called basidia. This group includes saprophytes, parasites, saprophytic parasites, and beneficial fungi. Understanding and identifying these types is key for an ISA Certified Arborist to assess your tree's health and safety.

Saprophytes

Saprophytic fungi play a vital role in breaking down dead plant material like wood and leaves, causing little to no harm to living plants. They are crucial for soil health and the global carbon cycle. While saprophytes may enter a tree through a wound and feed on dead tissue (heartwood), they don’t harm living wood. It’s not unusual for a tree to be hollow but still structurally sound, much like a building with a hollow interior but an intact frame. An ISA Certified Arborist can help assess whether your tree is stable despite internal decay.

Parasitic Fungi

Parasitic fungi target the living parts of the tree, particularly the cambium layer, which transports water and nutrients throughout the tree. This layer is rich in nutrients, making it an ideal feeding ground for fungi. Attacks on this area can weaken the tree’s structure, causing decline, structural instability and even death. Often, parasitic fungi don’t show visible signs like mushrooms or dieback until the tree fails structurally.

Saprophytic Parasites

Some fungi, like Ganoderma sessile, primarily break down dead material but can also become parasitic. These fungi can create hazardous conditions by feeding on both living tissue and dead heartwood. They often announce their presence with large, polypore mushrooms at the base of the tree.

Beneficial Fungi

Mycorrhizal fungi have a symbiotic relationship with tree roots. These fungi form sheaths around the roots or penetrate the roots directly, then spread into the soil in search of nutrients. The fungi exchange these nutrients for carbohydrates from the tree, benefiting both parties. Mushrooms growing around a tree’s root system may indicate healthy mycorrhizal fungi. However, not all mycorrhizal fungi produce mushrooms. Tree companies sometimes include these fungi in deep root fertilization mixes to boost soil health, especially in urban areas like Flint where mycorrhizal populations are often low.

What Should You Do If You Suspect Fungi in Your Tree?

If you suspect harmful fungal growth in your tree, it’s best to consult with an ISA Certified Arborist who is experienced in identifying fungi and assessing potential risks to tree health and stability. Some arborists use tools like the Resistograph Decay Detection Tool, which measures decay inside the tree. Just because a tree has fungi doesn’t mean it needs to be removed. Many options exist to improve the tree’s health and reduce risk, often at a lower cost than removing the tree.

Trees are incredibly valuable, and keeping them healthy benefits both the environment and your wallet. To arrange an inspection of your trees by one of our ISA Certified Arborists send us a message or give us a call today at 800-724-6680. By taking care of your trees, you can continue to enjoy their many advantages.