Do we need to remove the tree?
Your tree is in decline. It is an ash. All ash in MD (and the U.S.) will be killed by a non-native invasive insect called emerald ash borer(EAB). It may already be infected by this pest. Here is information on EAB and what can be done, however if the tree is more than 1/4th infested it will probably not recover:
http://extension.umd.edu/hgic/invasives/emerald-ash-borer Applying a pesticide is only a temporary solution, as this pest is here to stay.
Here is our webpage for deciding when to remove a tree:http://extension.umd.edu/learn/how-do-you-decide-when-remove-tree
Ash tree wood gets very brittle when they die and it makes removal dangerous. It is safer--and cheaper--to remove the tree before it completely dies.