How to Get Rid of Nutsedge in Bermuda Grass

Clemson Extension says nutsedges are often called nutgrass because they look like grass, and that mix-up is why the wrong herbicide gets sprayed. Grass stems are round and hollow. Nutsedge stems are triangular or V-shaped if you roll them between your fingers. The leaves are thicker and stiffer than Bermuda, with a crease down the middle, and they come in groups of three at the base.

Two perennial species show up in Southern lawns. Yellow nutsedge has light green leaves, a long tapered tip, and a yellow-green seedhead. Its tubers sit one at a time at the ends of rhizomes, and it usually emerges earlier. A mature plant is often 12 to 16 inches tall if you let it. Purple nutsedge has darker leaves that end more abruptly, a purple seedhead, and tubers chained along the rhizome. It usually stays under 6 inches and emerges later. Clemson notes that yellow nutsedge is more widespread because it handles cold better, and that purple nutsedge can be the more aggressive of the two where it is adapted. In South Carolina the two often grow in the same yard. The herbicide that works on one can be weak on the other, so look at the seedhead before you buy a bottle.

If the stem is round, you are probably looking at crabgrass or some other grass. If the leaf is a round lily pad on a stalk, that is dollarweed. Both like the same wet spots nutsedge likes. They are not the same spray.

Clemson says nutsedge prefers moist soil. A patch under a leaky head, along a downspout, or in a low spot that stays wet is a clue about the water, not about the fertilizer program. Once the plant is established it will also tolerate ordinary moisture and even drought, so drying the spot out later does not erase it.

It spreads by tubers (the nutlets), by creeping rhizomes, and by seed. New tubers start forming four to six weeks after a shoot comes up. Tubers and rhizomes can sit 8 to 14 inches down, and a colony can grow into a patch 10 feet across. Tubers also ride in on sod, topsoil, and tillers that were used in an infested bed. A crabgrass pre-emergent does not solve this. Clemson is direct: most herbicides aimed at grasses do not work on sedges, because nutsedge is not a grass.

The lawn's job is to stay thick enough that a new shoot has a hard time. Mow Bermuda at the height your grass type actually wants, feed it on a warm-season schedule rather than in winter, and water deeply and less often so the surface can dry between waterings. Thin spots from mowing too low, or from insects, are where the next tuber gets a start. The Bermuda lawn care guide is the rest of that program.

Very small patches can be dug. Clemson says to do it early in spring, before the plant makes more tubers, and to dig at least 10 inches deep and 8 to 10 inches past the leafy part you can see. Pulling a mature shoot usually snaps it off and leaves the tuber. In a vegetable bed, young plants can be hoed every two or three weeks before they have five or six leaves. In a lawn, digging is the mechanical option, and only while the patch is still small. Tilling a nutsedge patch spreads the tubers.

Sprays are post-emergent, and they work while the nutsedge is actively growing in warm weather with moisture in the soil. Clemson says to water the day before so the weed is taking up water and the turf is less likely to burn, and to avoid hot, dry days over 90°F. Leave enough leaf for the spray to land on. Do not mow it off the morning you spray, and wait about two days after, unless the label gives a different window. NC State times halosulfuron for late spring or early summer, when plants are growing hard, often in the range of a few inches tall or the 3-to-8-leaf stage. One pass rarely empties a tuber bank. Plan on a follow-up.

Match the active ingredient to the species and to Bermuda. Clemson's home-lawn table rates them this way, and the label still decides the rate:

• Halosulfuron (SedgeHammer and similar products) is rated good to excellent on both yellow and purple nutsedge, and Clemson lists it for Bermuda, zoysia, centipede, St. Augustine, and tall fescue. Those products need a nonionic surfactant. Clemson cites 2 teaspoons per gallon for the products it names. Repeat in 6 to 10 weeks.
• Imazaquin (Image Nutsedge Killer) is fair on yellow nutsedge and good on purple. Clemson lists Bermuda, zoysia, centipede, and St. Augustine, and marks tall fescue as not registered. Water in about a half inch. A repeat may be needed in 3 to 5 weeks. Do not use it on brand-new seed or sprigs, or while the grass is growing slowly. Because it also has pre-emergent activity, do not seed that spot for six weeks.
• Bentazon (Basagran and similar) is good on yellow nutsedge and poor on purple. It is labeled for Bermuda and several other lawn grasses. A second spray comes 7 to 10 days later. Skip it on turf that is not well established.
• Sulfentrazone is faster, but Clemson rates it only fair on yellow nutsedge and poor to fair on purple. A second spray about 30 days later is common. Some sulfentrazone mixes that also contain quinclorac are not registered for St. Augustine. Read the grass list.

Winter, when you only have brown Bermuda and buried tubers, is the wrong month. There is no leaf to absorb a post-emergent. Watch the plants in late spring and through summer, and write down which species you have so next year's bottle matches.

• Spraying a crabgrass preventer or a broadleaf weed-and-feed and expecting nutsedge to die. It will not.
• Using halosulfuron on spurge or dandelions. NC State lists those as weeds halosulfuron does not control. The reverse mistake is just as common.
• Pulling shoots all summer and leaving every tuber in the ground.
• One application, then surprise when new tubers sprout a month later.
• Spraying wilted nutsedge, or spraying when it is over 90°F, and scorching the Bermuda for a weak kill.
• Mowing the day of the spray, or tilling the patch and dragging tubers across the yard.
• Laying new sod or spreading topsoil without looking for nutsedge already in it.