My crape myrtles have not leafed out yet, but have many sucker shoots.
When Do Crape Myrtles Leaf Out in Kansas
Certified GKH Gardening Expert
You may want to make sure that the tops of the trees are still alive. This article will help with that:
If they are dead, the suckers at the base may or may not look like the parent plant. Many crepe myrtles, especially in colder areas, have been grafted onto inferior looking but sturdier trees in order to help them survive better. Whether you keep the suckers is up to you.
If the top is still alive, you just need to be patient. The cold weather this spring in many parts of the country has delayed blooming and leafing for some plants.