When  Appalachian Tree Service  is called to look at a property, sometimes a tree will still have green leaves and the client assumes it is healthy. In realty, the tree has major structural weaknesses.

To keep a tree alive, often only a few thin layers of active xylem and phloem are needed; however, structural soundness requires a greater wood volume.  Green, full-crowned, and essentially healthy trees can still fail due to structural defects