Oak Mazegill Mushroom Identification:

Oak mazegill is a mushroom that grows in heartwood or already rotting wood. These types of stemless mushrooms are called conks. The top of the conk grows in various shades of brown. The underside starts off as porous, but forms slits that look like an elaborate maze as it ages. Fruiting bodies can grow to be 1-8 inches in diameter and 3 inches thick.


This mushroom commonly grows on rotting oak trees. It may also be associated with old pruning wounds.

Biology & Symptoms:

As it grows, the fungus is known to cause brown rot of the heartwood, which can weaken the tree’s structure. The mushroom can grow year-round, but spores are typically shed during late summer and fall.

Oak Mazegill Mushroom Management:

Oak mazegill is a saprophytic fungus that grows on the heartwood of trees. The presence of this fungus could be an indication that there is internal rot within the tree. Like all fungi, once the tree has been infected, there is nothing that can be done to cure the tree. The best way to protect trees from developing oak mazegill is to optimize health and prevent fungal infection. Follow cultural practices such as proper fertilization, mulching and pruning techniques to optimize your tree’s health. Consult your local arborist if you think your trees may be showing signs of oak mazegill.

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