This is crapemyrtle bark scale, and insect that can cause severe damage to the plant. It can be difficult to control, but with persistence you should be able to get it under control.  Attached is a document providing management guidelines. For additional assistance you can contact your local Oklahoma County OSU Extension Service - https://extension.okstate.edu/county/oklahoma/.



Unfortunately, it does not look good. It appears to have either a root system problem or a disease, which could have initially started in the roots or on the stems or trunk. It appears to be in decline, and I don't think there is anything you can do at this point. Redbuds are susceptible to various canker and vascular diseases of which there is no control. One of the images show a decay fungus growing on the limb. That is an opportunistic decay fungus taking advantage of an already sick and dying tree. If you would like to know if a pathogen is responsible for the decline, then contact the Oklahoma County Extension Center for assistance to submit samples to the diagnostic lab.