I have a beautiful very large sycamore tree in my yard. There is a rather large hole (where a limb was) that has not healed and is open to the elements. This spring I noticed standing water in that hole and am worried about damage to the rest of the tree. Should I cover the hole? Someone suggested that I fill the hole with paper (for bulk) and then seal up the hole entry way with a poly spray filler. Sounds good to me. Any other ideas?

While it's diffcult to diagnose without an actual inspection, typically trees will decompartmentalize, or 'seal off' their wounds on their own. Adding paper or any other sealer to the hole, typically will not act as a 'band-aid' to help the tree heal. There is no significnt research that pruning tar, for example, aids in a tree's ability to recover. Best advice ould be to have a Certified Tree Expert or ISA Certified Arborist inspect the tree and offer specific recommendations.