Bermuda grass often is used as a turf grass in warm climates. It thrives in high temperatures, grows thickly and can withstand heavy traffic. The durable qualities that make Bermuda grass a desirable turf grass also make it a troublesome weed when it grows where it isn't wanted. And Bermuda grass often invades established lawns of other less-aggressive varieties of grass. Once it gains a foothold, it can be quite difficult to kill without injuring the surrounding lawn. Often a combination of control methods is necessary to keep Bermuda grass at bay for good.
Dig up patches of Bermuda grass with a shovel or trowel. Dig roughly 6 inches deep to bring up the roots as well as the blades (even small pieces that are left behind can regenerate into new stands). Re-seed the bald patches with the variety of grass seed that populates your lawn. Continue to remove any patches of Bermuda grass as soon as they emerge.
Cover large patches of Bermuda grass with black plastic mulch in summer. Mow the lawn and give it 1 to 2 inches of water. Cut a sheet of mulch so that it is roughly 3 inches wider on all sides than the patch of Bermuda grass. Cover the patch with the black plastic mulch and bury the ends of it 3 inches into the ground to keep it from blowing away. Remove the mulch when the light-deprived patch of grass is dead in six to eight weeks.
Raise the mowing height of your lawnmower to 3 to 4 inches in summer, as Bermuda grass needs ample direct sunlight, and longer grass will inhibit its growth. Withhold fertilizer in the summer when Bermuda grass is actively growing. Give the lawn 2 inches of water once weekly or when the top 3 to 4 inches of soil are dry.
Spray Bermuda grass in existing cool-season lawns with a Bermuda grass-selective herbicide, according to the manufacturer's instructions. Re-apply the herbicide at the intervals recommended by the manufacturer (usually every four weeks) until the Bermuda grass is gone.