Bermudagrass is a tough and extremely resilient plant. It's important to note that converting acres of bermudagrass back to native vegetation will take time. The plant has an extensive root system and a fast growth rate when conditions are suitable. This means that not every practice is likely to completely remove it; a combined approach is best.
In short, disking rarely kills bermudagrass and the plant will come back with a vengeance to, once again, take over whatever may have been planted in its place. Herbicide is usually required, and multiple sprayings per year are generally necessary. Sometimes multiple years of sprayings are also required, at least on a spot-treatment level. Removing the old thatch well ahead of the spraying is important to maximize the results, and this can be achieved by various ways such as burning or grazing.
For land managers on the edge of justifying a bermudagrass-to-native vegetation-conversion project, consider this. Two central Oklahoma habitats were surveyed, one dominated by bermudagrass and one a native range with scattered shrub thickets. Only six known quail food plants were identified within the bermudagrass field, and the abundance of those food plants was very low. The native range habitat provided 54 known quail food plants, 11 of which were important, high use foods. And this comparison doesn't even consider the high quality year-round cover the native range provided compared to the extremely poor cover of the bermudagrass field. In addition to wildlife benefits, native rangeland may also offer grazing benefits for producers.
While converting bermudagrass fields to native vegetation may take some diligent work and a little patience, the decision can be relatively easy, especially for quail lovers.