Bermuda grass is not an easy weed to kill. This is especially true if it has a foothold in other grasses that you wish to preserve. Killing Bermuda grass selectively is especially difficult and may take quite some time. There are two primary reasons that Bermuda grass is so hard to kill. First, it can multiply by sending out above-ground shoots which root themselves in any soil available. In addition, Bermuda grass also sends out rhizomes, or roots, which also grow new plants. Your problems don't end there--original Bermuda (as opposed to newer hybrids) also produces seeds that can be viable for up to two years. Your only hope in the war on Bermuda is to be persistent and never give up.
Stop watering your Bermuda grass if you can do so without harming other plants. Allow the ground to become completely dry and then rototill the area, bringing the roots to the surface where they can dry out further. Use a hard rake to pull out as many roots as possible after rototilling. Do not rototill if the ground is wet or if rain is likely within the following three weeks.
Withhold sunlight from your Bermuda grass if this can be done without destroying other plants. Lay a heavy black tarp over your Bermuda and weigh down the edges so no light reaches the plants. Keep your Bermuda grass away from light for at least eight weeks during the summer. Depriving Bermuda grass of sunlight during the winter months is not effective in killing this weed.
Kill your Bermuda grass by baking it during the hottest part of the summer in your area. Spread heavy clear plastic sheets over your Bermuda grass (if this can be done without killing other plants) and weigh it down. Allow the sun to bake through the clear plastic, killing your Bermuda grass with solar radiation. This works best on flat ground or on south-facing slopes--this does not work as well on north-facing slopes as the sun may not be hot enough in north-facing locations.
Apply herbicides in early spring to begin the killing process. There are several different types of herbicides available; talk to your local nursery person to determine which is best for your particular situation. Some herbicides kill everything they touch while others kill only grasses and still others are designed to kill Bermuda grass and to harm other grasses as little as possible. Apply a second application of the herbicide approximately three weeks after the first application. Always follow manufacturer's instructions when mixing and applying an herbicide.
Be persistent. Once you begin a program to kill Bermuda grass, keep at it, repeating the process as necessary until the last of your Bermuda is gone.