Thank you neighbors! I have received 4 recommendations for certified arborists. They are: 1) Arborel, a family owned company. 2) Horhut, recommended by the Pittsburgh Parks Conservancy 3) DC Culley, used by several HP people and 4) Call Plum Line Nursery for a recommendation I'll do some investigation, make some calls, and let you know the outcome. Our trees make our neighborhood. Jan M.