inherited a magnolia tree that had several limbs removed. as time goes by the cut areas have developed into 3-5" deep holes that have a brown mush inside. these limbs have to be seriously compromised. if i remove the sub trunks what are the chances of it happening at the new cuts. plus the tree will probably look butchered if those are removed.is there a treatment to prevent this from happening? i'm probably going to lose the tree.