I moved into a new home in the summer of 2013. It had a beautiful established weeping tree that I believe is a cherry. That winter was very harsh in Delaware, and the following spring I noticed that the tree did not bloom properly, but only on one side. One half of the tree seemed fine, and the other had very sparse leaf growth. I had bought a spray for bag worms for some evergreens, and sprayed some on the cherry also, hoping it would help. It did not. Now again this spring, the tree seems to have the same problem, on the same side. I have a weeping willow that seems to have the exact same problem. One side has bloomed beautifully, and the other side seems to be dying. Initially I thought these problems were from the harsh winter and that the trees just needed time to overcome the damage. But now I'm not so sure. The only thing that I've done differently is to start lawn care service. I didn't think this would damage my trees. Any thoughts on what could be happening?