Q: My question is a simple one. Will removing 4 medium sized nails from the trunk of an Oak tree kill the tree or should they be cut flush to the outside of the tree bark and left in.
If they are removed do you fill the holes with some kind of substance to prevent bugs or disease to enter. Thank you for your time.
Removing them will not kill the tree, but if you try to pull them out you may cause more injury in the process. Better to let the tree produce woundwood to cover the nails than to open it up to more opportunities for decay organisms to find their way in.
You do not need to put any substance on the area surrounding the nails.
In just a few years, all you'll probably see are roundish areas where the tree has grown over the nails. From this point on, the tree should continue to grow normally, without any harm from its "captives".