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Controlling nutsedge 
means controlling nutlets

Those not familiar with plant identification
 may confuse sedges with plants that are 

Nutsedges are warm season perennial weeds with upright, light yellow-green v-shaped leaves 1/8 to ½ inch wide and up to three feet long. They have parallel veins with a prominent midvein. Leaves grow rapidly in summer heat, often appearing well above the lawn grass. It grows so rapidly that it is usually two or three inches taller than the grass by the next day. Upon reaching maturity, it will produce a topknot of feathery, umbrella-like flower clusters. Two weeks after flowering, viable seeds are produced. 

It will also develop horizontal underground stems (rhizomes) with white tubers (nutlets) forming on the rhizomes. They reproduce by both seeds and nutlets, but mostly by nutlets. In one study, about 1 percent of the seeds produced resulted in established plants, however it must be taken into consideration that thousands of seeds are produced. The most common way for the plant to spread is by a slender rhizome that travels in every direction from the original plant. On most of the rhizomes, one or more nutlets form that will start new plants next season. A Georgia study found that a single nutlet produced 177 new plants occupying 2 square feet in a 6-month period.

Although purple and yellow nutsedge are basically the same, there are some differences:

Purple nutsedge: 

•  height – 1 to 2 feet tall

•  stems – longer than basal leaves

•  leaves – abruptly taper to point

•  seeds – dark brown

•  flowers – purple to brown with leaf-like bracts under flower cluster that are shorter than flowers

•  tubers – irregularly shaped from oblong to nearly round (up to .99 inches in length, usually < .39 inches thick, covered with red-brown papery scales) with buds scattered on the surface and have a bitter taste. Roots can grow to 51.18 inches (1.42 yards) deep in heavy clay. Rhizomes develop chains of up to 15 tubers at intervals of 1.97-9.84 inches along their length. Produces numerous plants along entire surface.

Yellow nutsedge (yellow nutgrass): 

•  height – ½ to 2½ feet tall

•  stems – as long as or shorter than basal leaves

•  leaves – gradually taper to point

•  seeds – light brown

•  flowers – yellowish-brown with leaf-like bracts under flower cluster that are longer than flowers

•  tubers – hard, smooth (scales shed with maturity), round (0.12-.6 inch in diameter, brown to black) at ends of some rhizomes with a sweet almond flavor. Produces 1-2 plants from apical end.

It is interesting to note that the species epitaph for both a tomato plant and yellow nutsedge is “esculentus” and was assigned by Linnaeus in the middle of the 18th century. This indicates that both plants are edible. The nutlets of one form of yellow nutsedge are grown as a food in parts of Africa and Asia where it is known as chufa. The Spanish prepare a drink called “horchata” from the nutlets that are said to taste like roasted almonds.

Nutlets develop rapidly, within six to eight weeks after the plants emerge, usually during late July and August. Nutlets may grow to be almost an inch in diameter. Unfortunately the nutlets may persist in the soil for many years. New plants emerge from the nutlets from late May to mid-July. Since nutsedges are perennial, a single plant can produce several thousand nutlets per season and each nutlet may sprout shoots up to seven times before carbohydrate reserves are depleted.

Nutsedges are classed among the world’s worst weeds due to the difficulty in controlling the nutlets and of the two species. Purple nutsedge is by far the most difficult to control since it develops multiple nutlets per rhizome. If you want to control it, don’t wait. Once it has formed nutlets, pulling it out will only remove the original plant.

Understanding nutsedge control begins with the realization that nutlets are the key to the weed’s survival. The nutlets may be thought of as a resting stage that allows the weeds to survive adverse conditions. It is widely believed that nutlets can survive almost anything. In fact, a large percentage of nutlets are often killed during dormancy, but even only one percent of the nutlets from a previous infestation are more than enough to bring back the population of these prolific weeds. 

Prevent nutlet production, and you eliminate the weed. But the nutlets can remain dormant and impervious to pesticides for years. They can also emerge from depths of three feet. Control programs should be aimed at preventing the formation of nutlets through prevention of growth of nutsedge plants. If no new nutlets are formed, tuber mortality will eventually eliminate nutsedge problems.

Nutsedge is most problematic during summers with above average rainfall. It particularly likes wet or moist sites or sites heavily irrigated. It is often an indicator of poor drainage. If that is the case, installing some type of drainage system, or adding soil to fill in the low area may help alleviate the problem. However it can grow in all soil types and can tolerate dry sites once it’s established. Management and environmental factors, including improper mowing, nutrient deficien-cies, insect damage, drought stress, etc., which stress or reduce the density or competitive ability of the turfgrass, will often lead to increased population of nutsedge.

To control nutsedge without chemicals, maintain a thick stand of lawn grass through proper maintenance. Warm season grasses compete better than cool season ones. Modify drainage in moist or wet areas. Check for nutlets in purchased soil or mulch. Pull nutsedge plants soon after emergence before nutlets can form. This can give some control, but pulling is not a cure since it may not remove all the nutlets from underground. The area will need to be rechecked periodically for regrowth. This method is effective only if preformed on a regular basis.

If herbicides are chosen as the control option, there are several available to be used in lawns once the nutsedge emerges. Unlike most lawn weeds, it is not controlled with applications of traditional annual grass weed or broadleaf weed control products. It requires the use of very specific herbicides. Regardless of the contol strategy selected, the plan should be initiated when the weeds are young and immature. However herbicides often will not give total control and multiple applications may be necessary. Complete control may require treating during at least two seasons to assure all of the dormant nutlets are killed. Herbicides for nutsedge control are generally applied from mid-summer to mid-fall. Pre-emergence needs to be used in the fall to help control the weeds the following spring.

The herbicide of choice for post-emergence control of nutsedge and other sedges in the lawn for many years has been MSMA. MSMA is sold under several tradenames, usually with either 4, 6, or 6.6 lbs active ingredient per gallon (concentration). Several applica-tions made 2 to 3 weeks apart may be necessary for complete control. MSMA is not safe to use on St. Augustinegrass or centipedegrass, but can be used on bermudagrass and zoysiagrass.

A newer herbicide that provides good to excellent post-emergence control of nutsedge and other sedges is Image (imazaquin). However, the Image label recommends mixing with MSMA for purple nutsedge control. Image is labeled for application to St. Augustinegrass, centipedegrass, bermudagrass, and zoysiagrass.

Manage (halosulfuron) is a new herbicide that provides excellent post-emergence control of sedges. Manage is labeled for application to St. Augustinegrass, centipede-grass, bermudagrass, and zoysia-grass.

Basagran (bentazon) T/O provides good to excellent post-emergence control of yellow nutsedge and annual sedges. Basagran T/O does not control purple nutsedge. Basagran T/O is labeled for application to St. Augustinegrass, centipedegrass, bermudagrass, and zoysiagrass.

Commercial turfgrass managers may use Basagran (bentazon) or herbicides containing MSMA. 

Home gardeners should look for herbicides, such as FL Crabgrass, Nutgrass & Dallis Grass Killer; FL Nutgrass, Poison Ivy & Vine Killer RTU; FL Weed-Out Plus Weed & Grass Killer; HY Super Concentrate Killzall Weed and Grass Killer; Roundup®, that are specifically formulated for nutsedge control. Several companies make a crabgrass and nutgrass killer.

Always read, understand and follow the label directions. Two to three applications 4-7 days apart are generally required. Spot treat only the areas that have nutsedge.

Misapplied herbicides can damage desirable plants. To reduce the chances of damage:

•  Watch wind speeds to avoid drift. Often early mornings are less windy than later in the day. 

•  Apply herbicides when air temperatures are between 65 and 85 degrees F.

•  Do not apply herbicides when precipitation is expected within 24 hours. 

•  Do not mow for a few days prior to or following application. 

•  When possible, to reduce unnecessary pesticide use, make spot treatments rather than treating large areas.

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