Expert Arborist Advice

Tree Care Tips

Why Do I Have Mushrooms on My Trees?

Armillaria mushrooms can be a sign of root rot

Mushrooms on trees may seem like a normal part of the ecosystem, but unfortunately, most of the time they indicate a problem.

In the spring, you may see clusters of small brown-capped mushrooms growing at the base of your trees. These are armillaria mushrooms, also known as honey mushrooms, and they’re a bad sign for your tree.

They can be found on hardwood and coniferous trees, including balsam fir, birch, spruce, pine, white cedar, larch, maple, poplar and oak trees.

When Are They Found?

Armillaria mushrooms on trees can be seen from late summer through fall.

Armillaria Root Rot Symptoms

It’s possible that your tree won’t show any signs of infection from armillaria root rot before you’ve noticed the clusters of mushrooms. However, the mushrooms are a sign that the fungal infection has wound its way deep into the tree.

When you see mushrooms on trees, it means that spores have already spread through the tree. The fungal infection is now causing mushrooms to grow at the base of the trunk.

Other signs of fungal infection in trees can include:

  • Discoloured leaves
  • Poor leaf growth
  • Leaves dropping early
  • Dead, dying or brittle branches
  • A lean to the tree

What Causes Infection?

White fungus growing at base of tree

Poor soil conditions, like overly wet or dry soil, or compacted soil, can leave a tree vulnerable to fungal infection. Damage to the tree can also expose the interior of the tree and leave it open to infection from fungi. Cuts and scrapes from broken branches, storm damage, damage from construction or other equipment, and even pruning can leave wounds on a tree.

What is root rot? Root rot is decay of the roots of the tree. It leaves trees unable to absorb the nutrients they need from the soil, causing damage or death to the tree over time. Spores from fungi are present in the soil naturally, but they will stay dormant unless the right soil conditions for them develop.

Can I Eat the Mushrooms?

Never eat any mushroom that hasn’t been positively identified by an expert! The caps of honey mushrooms are technically edible, but must be cooked properly and can cause gastric distress in some people.

How to Manage Armillaria Mushrooms on Trees

Removing the mushrooms from the tree generally won’t accomplish anything, since the fungus has already spread throughout the tree. Removing mushrooms could even help the mushroom spores spread to nearby trees and plants.

Instead, call an arborist, who can assess how widespread the armillaria mushroom disease is in the affected tree. If the infection hasn’t spread widely, it may be possible to treat and save the tree, removing affected parts.

In many cases, this is a fatal infection for trees, and removal will be your only option. Again, a qualified tree care professional is the best person to assesss how bad the infection is and advise you on the best course of action.

If removal is recommended, your arborist can come up with a removal plan and apply for any necessary permits.

Is your tree showing signs of fungal infection or have you found mushrooms on your tree? Get an arborist to check it out as soon as possible — contact Vista Tree now

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