I have a 40 year old honey locust tree that has sparce leaves toward the top of the tree. Lower branches have leaves, but not as dense as usual. Other trees in our area seem to have the same problem, but not all honey locusts in the area. This has never happend before. This is an established neighborhood. What could possibly be the cause?

Greetings Tom:

Unfortunately, many tree/forest health questions are just too general to answer without an on-site assessment. It may be biological (pest/pathogen), it may be environmental (weather related phenomena, pollution, soil compaction, etc.), or it may be a combination of biological and environmental agents.

If you really want to know what is going on with your tree, I would strongly urge you to contact a local professional consulting forester / certified arborist for an on-site assessment.

IL Professional Consulting Foresters:

http://dnr.state.il.us/conservation/forestry/

IL Certified Arborists:

http://www.illinoisarborist.org/CertifiedArboristsNew.htm

Best of luck!