A. Pruning paint might help in this case and may be worth a shot. Most people in the know no longer recommend pruning paints to cover wounds on trees. They just sanitize it and let it air dry.
The reason for not recommending pruning paint is because research has found pruning paints to be primarily cosmetic and do not assist the tree in healing. Healing is best if the wound is left alone without the use of paints.
|Topworking an apple tree to a new variety using pruning sealer and nursery tape to seal in moisture until healing is underway.|
There is some research that supports the idea pruning paints may actually cause some harm to an open wound. But pruning paint will not kill a tree or severely weaken a tree. Compounds similar to pruning paints are still used in propagation of trees such as grafting and topworking.
In this particular case I would go ahead and try it since the benefits will probably outweigh any negatives to the tree.