Nutgrass, more accurately known as nutsedge, is a common weed in lawns. This includes lawns made of bermudagrass (Cynodon dactylon), a lawn grass variety grown throughout U.S. Department of Agriculture plant hardiness zones 7 through 10. You'll likely encounter two types of nutsedge: purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus). The former thrives in USDA zones 9 through 11 while the latter grows in zones 8 through 11. If you notice nutsedge in your lawn, you have several options for controlling and killing this weed.
Stop watering your bermudagrass lawn, and wait to apply irrigation until the grass shows signs of wilting. Bermudagrass is a very drought-tolerant variety of grass. Meanwhile, nutsedge thrives best in very moist lawns, and drastically reducing your irrigation can help dry out and kill this weed.
Increase the mowing height of your lawn to 2 inches, which is the maximum height recommended for bermudagrass. This increases the amount of shade at the soil level of your lawn. Nutsedge doesn't tolerate shade very well, and the increase in shade can help weaken or kill existing weeds while reducing the rate of new weed growth.
Put on gardening gloves and hand-pull the nutsedge. Grasp it at its base and pull upward, being careful to also remove the tuber at the base of each plant. If you find uprooting difficult, try weeding shortly after watering your bermudagrass lawn, as moist soil conditions makes it easier to hand-pull weeds.
Apply an imazaquin- or penoxsulam-based nutsedge herbicide if all other methods of cultural and physical control fail to eradicate this weed to your satisfaction. For the best results, use a product that's labeled as safe for bermudagrass. Image's Nutsedge Killer is an example of an imazaquin product. Attach the ready-to-use bottle to a garden hose, turn on your hose's faucet, then open the spray nozzle on the bottle and mist the product evenly across the entire surface of your bermudagrass lawn. Scott's Green Light Wipe-Out Tough Weed Killer for Lawns is an example of a penoxsulam product. A single 10-pound bag will treat 2,940 square feet of warm-season grass, such as bermudagrass; simply broadcast it evenly using a fertilizer spreader two to three days after you mow your lawn.