I am no tree expert. I have heard that the general rule is to prune trees when the tree is dormant or in winter which will also protect it from pests and fungus. Anyway I have a customer that wants two Crate Myrtle trees (I spell it like it sounds) cut way back. They stand appox 15 ft and he wants to bring them back to about 7 feet. Can this be done without hurting the trees. Appreciate any help.