There are large white and gold fungal growths at the base of an oak tree in my yard. This is the second summer-fall that the fungus has formed, and is larger (multiple locations) this year. Should I do something to treat it and protect the tree? Please see the attached pic.
Linn County Oregon
This appears to Inonotus butt rot, be a common infection of oak trees in our region. It produces an annual conk each fall (as opposed to some others that have perennial woody conks). The conks indicate decay, the result of some past injury. Here is a link to the PNW disease handbook, with some more information https://pnwhandbooks.org/plantdisease/host-disease/oak-quercus-spp-inonotus-root-butt-rot
I do not the tree can be "protected" at this point nor treated now that it is established in the tree. As a rot of the roots and lower trunk, it can likely affect the stability of the tree. It is hard to tell the extent of the rot (but large muliple conks is not promising). How much of a safety concern it is probably depends on the situation: Is it close to the house or other infrastructure to put people or property at risk.