Why Mushrooms Growing On Trees Is Bad News

Mushrooms are excellent in soup, stir-fry, spaghetti sauce, and pizza. While mushrooms are great to use in the kitchen, spotting them in the garden on a tree is not a good sign for the plant. The mushrooms are feasting on the tree, which may not be alive for long. Here's what you should know about mushrooms growing on trees. 

Mushrooms Break Down Organic Matter, That's Good—Most Of The Time

Mushrooms are the visible fruiting bodies of a fungus that may attack living tissue but usually confines itself to feeding on dead, organic matter, such as rotten wood. This process is mainly beneficial, as the breakdown of wood returns its constituent matter to the soil to enrich it. However, when you see mushrooms growing on a living tree, this is a warning sign that all is not well with that tree.

Shelf Mushrooms Are Common Tree Feeders

What you're looking at (pictured above) is a stunning form of shelf or bracket mushroom called a "turkey tail," for looking like the variegated feathers of the beloved bird. Shelf mushrooms resemble the shape of a pizza. Instead of having spore-bearing gills on their undersides, they have zillions of tiny holes. They can grow straight out from the side of a trunk or up from the ground, decomposing dead wood in a tree. The dead wood can be major roots or the heartwood in the center of the trunk that gives the tree its strength.

WATCH: Grumpy's Field Guide To Mushrooms

Why do some trees get shelf mushrooms and others don't? One cause is stress brought on by things like extended drought, compacted soil, and overly wet soil. Healthy, vigorous trees are less prone to infection, just like people.

When Planting New Trees, Follow Best Practices For The Root And The Trunk

Then there's physical damage. Take a close look at the tree's base (pictured above). You'll see a cavity probably caused by a piece of landscape equipment. If you have sharp eyes, you'll also notice thick plastic straps encircling the base of the trunk. These straps hold the root ball together when planting a balled-and-burlapped tree. You should always cut the ones that circle the base of the trunk after planting, lest they strangle the tree when it grows. In this case, they weren't. Roots died, and the turkey tails appeared.

Once this happens, you can't save the tree. You can cut off the shelf mushrooms, but they'll regrow because the fungus is inside. Eventually, they'll hollow out the tree, making it prone to falling in high wind. The best thing to do is remove the tree before it falls on you.

Can you plant a new tree in the same spot? Yes. Just keep it healthy, don't damage the trunk or roots, and don't pile up a volcano of mulch around the trunk.