Cooperative Extension Service
The University of Georgia College of Agricultural and Environmental Sciences
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Controlling Nutsedge

Mark Czarnota, Ph.D., Ornamental Weed Control Specialist
Department of Horticulture, 1109 Experiment Street
Griffin, GA 30223

The Plant:

Nutgrass is a difficult weed to control in the landscape. There are approximately 20 genera of sedges in eastern North America, but the genus Cyperus contains the worst weeds. The two most notable weedy representatives from this genus are yellow nutsedge (Cyperus esculentus) and purple nutsedge (Cyperus rotundus). These sedges will be the most common sedges encountered in the landscape and turf. They both are herbaceous perennial plants that primarily reproduce from tubers. Tuber production among sedges is rare. In fact, of all the known sedge species, only yellow and purple nutsedge produce tubers.

Herbicides:

Pennant (metolachlor), Basagran T/O (bentazon), and Image (imazaquin) are selective herbicides for controlling yellow and purple nutsedge in the landscape. Pennant is a preemergent herbicide for the control of yellow nutsedge. Basagran T/O, a selective postemergent herbicide, works best on controlling yellow nutsedge in certain ornamentals. Image, a selective postemergent herbicide, works best on controlling purple nutsedge in selected ornamentals. Unfortunately, there is not a selective postemergent herbicide that effectively controls both yellow and purple nutsedge. Manage (halosulfuron) is a relatively new postemergent herbicide for controlling of both yellow and purple nutsedge in turfgrass. It also can be used as a non-selective post directed application for the control of yellow and purple nutsedge in established woody ornamentals. Roundup (glyphosate) can also be used as a non-selective post directed application for the control of yellow and purple nutsedge.

Since no herbicide selectively controls both sedges, it is important to apply the right chemical to the right sedge. Basagran T/O effectively controls only yellow nutsedge, while Image effectively controls only purple nutsedge. With the inability of these chemicals to control both of sedges adequately, it is important to identify the differences between yellow and purple nutsedge so you can apply the proper chemical to the proper nutsedge.

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Figure 1. Yellow nutsedge in flower.		Figure 2. Purple nutsedge in flower.

In flower, yellow and purple nutsedge are easy to distinguish between one another (Figures 1 and 2). Yellow nutsedge flowers are yellowish while those of purple nutsedge are purplish. Many times, however, you will encounter nutsedge plants that are not flowering, and you will have to rely on vegetative characteristics to identify these plants. Yellow nutsedge leaves have pinched tops, while the leaf tips of purple nutsedge are keeled (just like a boat, Figure 3).

Figure 3. Leaf tips of Yellow and Purple Nutsedge. Notice the difference in leaf tips. Purple nutsedge has a keel shape, and yellow nutsedge is pinched.

Herbicide Application:

Application of the herbicide at the proper time is important for controlling sedges. As with all preemergent herbicides, if the herbicide is applied after the plant is emerged, control will be poor. Pennant will not provide good control of yellow nutsedge after the leaves have emerged. For best postemergent control of yellow and purple nutsedge, apply herbicides after the foliage has emerged and is at least 4 to 6 inches high. This will assure adequate foliage to effectively absorb the herbicide. Basagran T/O requires approximately 3 to 5 days before herbicide symptoms appear. Image requires approximately 7 to 14 days before herbicide symptoms appear. Image requires the use of a non-ionic surfactant (0.25% V/V), and Basagran T/O requires the use of a crop oil (1.0% V/V).

Basagran T/O and Image can be applied over-the-top of selected ornamentals (Table 1).

Table 1. Ornamentals labeled for over-the-top applications of Basagran T/O and Image.
Herbicide:	Ornamental:
Basagran T/O (5 teaspoons/1 gallon of water; treats approximately 1,000 ft²). Don't forget to add a surfactant or crop oil.	Ajuga, English Ivy, Liriope, Mugo Pine, Pachysandra
Image (0.5 ounce/3 gallons of water and spray to set)	Yucca, Juniper sp. (see label), Liriope, Pachysandra

Other Control:

Nutsedges are not good at competing with other plants for light, space and nutrients. To help reduce nutsedge infestations in ornamental beds, some type of mulching material should be used to cover bare soil. If possible, hand weeding and cultivation on a regular basis can also help reduce nutsedge populations.

Before using any pesticide, be sure to read and follow the label.

Trade and brand names are used only for information. The Cooperative Extension Service, University of Georgia College of Agricultural and Environmental Sciences does not guarantee nor warrant published standards on any product mentioned; neither does the use of a trade or brand name imply approval of any product to the exclusion of others which may also be suitable.

Attention!

Pesticide Precautions

It is the responsibility of the pesticide user to observe all directions, restrictions and precautions on pesticide labels. It is dangerous, wasteful and illegal to do otherwise.
Store all pesticides in original containers with labels intact and behind locked doors. KEEP PESTICIDES OUT OF THE REACH OF CHILDREN.
Use pesticides at correct label dosage and intervals to avoid illegal residues or injury to plants and animals.
Use pesticides carefully to avoid drift or contamination of non-target areas.
Surplus pesticides and containers should be disposed of in accordance with label instructions so contamination of water and other hazards will not result.
Follow directions on the pesticide label regarding restrictions as required by State or Federal Laws and Regulations.
Avoid any action that may threaten an endangered species or its habitat. Your county extension agent can inform you of endangered species in your area, help you identify them and, through the Fish and Wildlife Service Field Office, identify actions that may threaten endangered species or that habitat.

Circular 867-9/May, 2004

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