Nutsedges are a very persistent and aggressive weed that commonly infests lawns, flower and vegetable gardens, and home landscapes. Nutsedge can be difficult to eradicate and successful control involves both cultural and chemical management methods. Once controlled, any new infestations should be managed right away to prevent spread of these aggressive and difficult-to-control weeds.
Nutsedges are often miscalled nutgrass because they closely resemble grasses. Correct identification is very important because most herbicides for grass control are not effective on sedges. Grasses have flat blades where sedges have “edges” or a triangular or V-shaped in cross section. Sedge leaves are thicker and stiffer than most grasses and are arranged in groups of three at the base.
Most nutsedges are perennials, meaning their leaves will die back when the temperatures decrease. Tubers and rhizomes (underground stems) survive in the soil and will sprout the following spring. The tubers and rhizomes can grow 8 to 18 inches below the soil surface. New tubers begin forming 4 to 6 weeks after a new shoot emerges. Individual nutsedge plants may form patches 10 feet or more in diameter. While nutsedges prefer moist soil, they can also thrive in dry soil.
The two most common types of nutsedges in South Carolina are purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus). Yellow nutsedge is more cold tolerant and is therefore more widespread. In spots where purple nutsedge has been more adapted, it can be more vigorous than yellow nutsedge. Correct identification is critical to successful control because the two nutsedges differ in herbicides susceptibility.
Nutsedges thrive in moist areas and their presence often indicates that drainage is poor, irrigation is too frequent, or sprinklers are leaky. It is possible to eliminate very small patches of nutsedge by digging. Dig at least 10 inches deep and at least 8 to 10 inches beyond the diameter of the above ground leafy portion of the plant. This will ensure removal of the spreading tubers. This is best done early in the spring, before more tubers are produced.
Nutsedges can be controlled chemically with postemergence herbicides. Herbicides also vary regarding the desirable plants they can be safely used around without causing damage. Always check the label to make sure the pesticide you choose will not damage desired plants.
Apply herbicides when nutsedge is actively growing in warm conditions with adequate soil moisture. Water the lawn the day before spraying to help protect the turfgrass and to assure that the weeds are actively growing (so they will better take up the herbicide). Applications during droughty conditions or when the nutsedge is not actively growing may result in poor control. Avoid applications during hot or dry weather (> 90 °F) to minimize the chances of injury to the turfgrass. Follow the instructions on the product label for the most effective application rate and procedure.
Avoid mowing before a postemergence herbicide application to allow for adequate foliage to absorb the herbicide. Also avoid mowing for two days after application to allow enough time for the plant to absorb and move the herbicide down to the tubers. The length of time to allow before and after mowing varies with the product. Always read the label for specific instructions. Herbicides with the active ingredients bentazon, imazaquin, halosulfuron, or sulfentrazone are good to use on nutsedges on turfgrass. Be sure to read the label to for the rate to apply to your specific turfgrass.
Nutsedges do not grow well in the shade. By changing landscape plantings and adding a tall, dense ground cover or shrub, you may be able to reduce the nutsedge’s growth this way. Many times, nutsedge is brought into the home landscape from bulk soil or nursery plants that have been infested. Inspect your plants and reject plants that contain any visible nutsedge.
Chemical control in the landscape should be used with caution. Depending on the herbicide used (bentazon, halosulfuron, or imazaquin), the herbicide may harm some ornamental plants, while it will not have an effect on others. Please consult the label prior to all spraying.
Pulling the plants out by hand is relatively ineffective because tubers deep in the ground usually bread off the pulled shoots. Very young plants can be controlled by hand weeding or hoeing if they are consistently weeded out before they have 5 to 6 leaves. In the summer this will require weeding at least every 2 to 3 weeks, but doing so will cause a deletion of energy reserves and resprouting will soon stop. Once nutsedge plants have more than 5 or 6 leaves, they begin to form tubers, usually in May or June.
Using a tiller to destroy mature plants in the garden will only spread the infestation because it moves the tubers around in the soil. However, repeated, frequent tiling of small area before the plants have 6 leaves can gradually reduce populations. Tiling for nutsedge suppression should be limited to times when the soil is dry. When the soil is wet, tubers are more likely to adhere to the equipment and move to other areas of the garden.
Pelargonic acid is a naturally occurring fatty acid found in many plants. Herbicides containing pelargonic acid are labeled for post-emergence, non-selective, weed control. The ammonium salt of pelargonium also called nonanoic acid is an herbicide. These produces have “warning” as the safety signal word on the label. Non-target plants must be shielded to prevent spray contact and potential injury.
Plant essential oil-based herbicides are made from naturally-occurring plant sources. Orange oil has “caution” as a signal word and acetic acid has “danger” listed. Acetic acid can cause eye damage so wear eye protection. Vegetable plants must be shielded to prevent damage from these herbicides.
Always read the pesticide label and follow its directions exactly. You may only use the pesticide on sites or crops listed on the label. Never use more than the label says. Be sure to observe all special precautions that are listed on the label.
Clemson Extension will be having their annual fruit tree fundraiser. If you are interested in an order form please call the Extension office at 843-774-8218 extension 0.
For more information on nutsedge, please visit the Home and Garden Information Center website at hgic.clemson.edu. Tune in on Tuesday nights to watch “Making it Grow” at 7pm on SCETV or mig.org. Email Outen at callenb@clemson.edu.
*Clemson University Cooperative Extension Service offers its programs to people of all ages, regardless of race, color, gender, religion, national origin, disability, political beliefs, sexual orientation, gender identity, marital or family status and is an equal opportunity employer.
