The first steady rains of fall bring out mushrooms all over Snohomish and King County lawns, and most of them are harmless. But when mushrooms, conks, or shelf-like growths show up right at the base of a large tree, especially a Douglas fir, they can be the visible part of a root or butt rot working underground.
Root diseases common in western Washington, like laminated root rot and Armillaria, weaken the roots that anchor a tree long before the canopy looks sick. A tree can hold a full, green crown while its root system slowly loses its grip, which is why some of the trees that come down in winter storms look perfectly healthy until they tip over.
A few mushrooms don't mean a tree is doomed, and not every fungus is a problem. The honest answer comes from looking at the whole picture: where the growth is, whether there's resin bleeding or soft wood at the root collar, how the crown looks, and what's nearby if the tree were to fail. That's a quick, straightforward assessment, and it's far better to have it now than after the first big windstorm.
Have you noticed mushrooms or shelf fungus growing at the base of any of the big evergreens on your property this fall? #TreeHealth #PNWTrees
A real close-up of mushrooms, conks, or shelf fungus at the root collar of a large Douglas fir on an Arbor Vet job, ideally with part of the trunk in frame for scale. A wider shot of the tree showing a full green crown makes the "looks healthy" point. Authentic photos strongly outperform stock images.
Canva text suggestion: "Mushrooms at the Trunk? Look Closer" or "A Green Crown Can Hide Weak Roots"