Crape myrtle disease
My large, two stories tall, is not well. The leaves are orange and sparse forthe second year in a row. I just noticed that all of the three large trunks coming up from the ground are missing bark. No mowing takes place sonow physical damage I can think of. I want to save it. An arborist didnt know what was wrong and suggested I contact you.
We viewed your photos. We cannot say for sure why the tree is declining. We notice a possible canker near the base of the trunk. As cankers enlarge they kill the living woody tissue within the branch or trunk. This can be caused by poor maintenance or site problems (planting too deeply, drought, poor drainage, etc.) Symptoms include branch dieback. There is no chemical control. http://extension.umd.edu/hgic/cankers-trees-and-shrubs
All you can do is prune dead wood and keep the tree well watered during dry periods. Make sure mulch is no thicker than several inches and keep away from the base of the plant. It may be time to replace the tree.