How can you kill bluestem grass in bemuda lawn?

You build a weed wick (google "weed wick applicator") that hangs in front of or behind whatever vehicle (ATV, mule, Golf cart, tractor) you have that hangs horizontally about 12" above the desirable grass tops. The wider the wick, the faster the coverage. Fill the wick feeder with Roundup concentrate and after the wick has become moist with the herbicide, simply drive over all of the area you wish to treat. The herbicide wipes onto the blue stem tops without contacting the shorter grasses below. In a few days you will begin to see the unwanted grass begin to die out. Works great. Good luck.