Darkness Inside Oak tree branches

Question

I recently pruned our 10 oak trees- all of which are around 8-15 years old- and noticed that on a few of the trees the branches seem to be dying inside. Not sure if that is actually the case or if something else is going on. I’ve included a photo of the area post-prune.

Answer 1

This is normal spotting. This could be from an injury by insect, or just overall minor injury. This is nothing that would seem worrisome or out of the ordinary.