In Toronto, in the most shady part of our backyard, just behind the kids’ play structure, we took down a sick birch tree, leaving the trunk. At the base of the trunk, a poop like fungus is growing and seems to be spreading in the mulch toward the play structure ( most shady area). What is it, should I be worried? What should I do about it?
Mushrooms are the fruiting body of a fungus, and they often sprout after the fungus has already established itself inside the tree. By the time mushrooms form, the internal structure of the tree is usually already compromised.
Some types of fungi attack tree roots directly, while others enter the tree through a wound. Cuts and scrapes in bark or roots open a tree to fungal attacks. These wounds may have come from a nick by a lawn mower blade, excavations, pruning, or from wind and ice damage. Once the fungus finds a way into the tree’s interior tissue, it produces an enzyme that breaks down wood fibers, releasing nutrients needed to feed the fungus.
Tree fungus will also spread along buried roots, there may be one running in the direction of the play structure. The fungus reproduces by releasing spores from it’s fruiting body. Unless the fruiting body is removed, the fungus will continue to grow and spread. Do not place the mushrooms in your compost.
You may wish to call in an arborist to kill the stump and therefore remove the food supply for the fungus. To find a certified professional arborist visit the Ontario branch of the International Society of Arboriculture here.