markf12 wrote:
Around here, any tree that is big enough to climb can be pretty much guaranteed to have substantial heart rot - to the point where I have yet to find a tree I consider to be climbable. The flip side of this is that two of my favorite wild edible mushrooms, the sulphur shelf (Laetiporus sulphureus) and Hen of the Woods (Grifola frondosa) seem to be only found on northern red oaks around here. Both of these are heart-rot fungi.

The question becomes how much heart rot is too much. For our red oaks you can see by the overall state of the crown, the severely compromised trees have very ragged looking crowns. Some of these trees are so large that they can handle a certain amount of heart rot and have vigorous and healthy crown structure. Two very large red oaks that I've been looking at have Hen of the Woods growing out of the roots ten feet from the bole (in September), clearly attacking the tree but only a small part of the structural scenario for these trees because of the overall massiveness. If the fungus is right on the bole then look out. Definitely want to be inspecting and sounding the bole to assess. In our area pin oak tends to fall apart more readily than red oak in old age. A leaning old red oak is to be regarded with suspicion.

These are my observations of the red oaks that I've been climbing for nearly 3 years, I'm not an expert arborist.
-moss