Ganoderma exists in the soil and enters tree roots through wounds in the root tissue. Wounds are most likely to occur with digging or construction in the root zone — installation of sidewalks, patios, driveways and retaining walls can cause substantial damage to tree roots.

Lawn mowers and weed trimmers that contact exposed tree roots or the base of the tree also create wounds that allow Ganoderma and other similar fungi to move into a tree.

The fruiting structures that indicate the presence of Ganoderma are typically brown to reddish brown with creamy margins. They look more like a dried pile of goop, than a standard mushroom and sometimes even look like they have been varnished. Sometimes they are yellowish or purplish.

They appear at the base of the tree near the soil line or on exposed roots but never in the high branches of a tree. One species of Ganoderma produces a shelf-fungi known as the artists’ conk because the underside can be drawn upon.

If you observe what look like Ganoderma fruiting structures on a tree in your yard, there are a few things to consider. Most important is the presence of a target — meaning something that could be damaged if the tree fell on it.