My pink cascade weeping peach red leaf tree is not yet forming leaves on two-thirds of its branches. Most branches are still flexible and not yet brittle or dead. The trunk looks healthy I am concerned.
Many areas of the country are experiencing a colder than usual spring and if this is the case where you are, this may have delayed leafing in the tree.
It may also have a fungus that is delaying it. To be on the safe side, treat the tree with a fungicide. I personally like neem oil. This article will have more information on it: