What is this fungus and could it indicate internal decay in my Douglas-fir?


It’s Phaeolus schweinitzii, which is called several different things such as "cow pie fungus" or “Schweinitzii root and butt rot.” If your tree is near a house, this is definitely an issue warranting further inspection and possible tree removal. An arborist should be able to detect internal decay in a Douglas-fir.

This fungus could definitely indicate internal decay of the root and butt of a tree – the lower trunk up to 8 feet – but it’s difficult to know how much rot is there just by looking at a photo of the spore-producing structure known as the conk. The conk has more bright colors in the fall and then turns brown and looks like a cow pie. It will be attached to a root below it but can occur on the tree butt also and be shaped more like a bracket.

Was this page helpful?

Related Content from OSU Extension

Have a question? Ask Extension!

Ask Extension is a way for you to get answers from the Oregon State University Extension Service. We have experts in family and health, community development, food and agriculture, coastal issues, forestry, programs for young people, and gardening.