I live in zone 5. Last year I planted a weeping cherry and it was beautiful. This spring it started it's new growth and then it seemed to stop and mostly all the new leaves fell off. Most of the branches look dead. Is it from a late freeze? This tree is 8 ft. tall and the trunk it smooth and white and looks healthy, with no sign of disease. What can I do for it. We have had a wet spring and water is not the problem. Thanks for any help. Mfs.