Q:Our locust tree has lost all its leaves on about 1/3 of the understory. We see no insects, worms, etc. The rest of the tree looks full and thick. What could this be? Treatment?
My guess is heat stress. Trees will drop their leaves to conserve moisture. But it were my tree I would enlist the advise of a profession and get an on-site inspection from a certified arborist. To find one in your area go to www.tcia.org and enter your zip code, Best And Happy Yardening, Nancy