Louisiana Home Lawn Series banner. A guide to maintaining a healthy Louisiana lawn.

Purple Nutsedge


Description

Purple nutsedge (Cyperus rotundus L.) is a perennial weed common throughout Louisiana. Its leaves somewhat resemble a grass. However, it is actually a member of the sedge family. Its flowers produce few viable seeds, but it spreads primarily through underground tubers connected by rhizomes (underground stems). These tubers can form underground chains, allowing purple nutsedge to establish rapidly. Purple nutsedge has darker green leaves with rounded leaf tips and is generally shorter in height compared to yellow nutsedge, which has lighter green leaves with pointed leaf tips and is generally taller. Also, purple nutsedge produces tubers in connected chains.

Picture 1_Purple nutsedgepng


Identification

Purple nutsedge can be identified by its shiny, green, grass-like leaves that are rounded at the tip. All sedges have triangular stems. The flower has multiple stalks that are purple to reddish-brown in color. Purple nutsedge produces small, brown tubers that are connected by rhizomes (underground stems) to form underground chains. For more information on Purple nutsedge identification and characterization, reference the USDA Plants Database.

Hint: Purple nutsedge has darker green leaves with rounded leaf tips and is generally shorter in height compared to yellow nutsedge; which has lighter green leaves with pointed leaf tips and is generally taller. Purple nutsedge also produces tubers in connected chains.

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Purple flower

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Rounded leaf tip

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Triangular stem

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Tuber root chain


Cultural control practices

The best way to prevent or reduce weed encroachment is to maintain a healthy lawn through regular mowing and proper fertilization and soil pH management. Properly maintaining a lawn through these cultural practices promotes dense and vigorous turfgrass, which allows the grass to better compete with weeds. Below are the recommended mowing and nitrogen fertility rates recommended for each turfgrass species. In addition to these lawn care practices, manual removal of weeds may also be necessary. Physically removing purple nutsedge is difficult because of the chain of rhizomes. Increasing drainage can help reduce purple nutsedge occurrence.

Turfgrass Species Mowing Height Nitrogen Rate (per 1,000 ft2 per year)
Bermudagrass 1 to 2 inches Up to 3 pounds
Centipedegrass 1 to 2.5 inches Up to 2 pounds
St. Augustinegrass 2.5 to 3 inches Up to 3 pounds
Zoysiagrass 1 to 2.5 inches Up to 2 pounds

Chemical control practices

In addition to cultural practices, herbicide applications may be required to achieve effective weed control. Several post-emergence herbicides control purple nutsedge in lawns. However, no single application will provide season-long control.

When applying any type of herbicide, you must follow the manufacturer’s labeled directions. For more information regarding pesticides for turfgrass please reference the Louisiana Suggested Chemical Weed Control Guide.

St. Augustinegrass Centipedegrass Zoysiagrass Bermudagrass
Post-emergence Herbicide Active Ingredients


halosulfuron Yes Yes
Yes
Yes
sulfosulfuron Yes
Yes
Yes
Yes
imazaquin Yes
Yes
Yes
Yes
trifloxysulfuron No No Yes
Yes
sulfentrazone Yes
Yes
Yes
Yes

For information regarding weed identification and control options please contact your local LSU AgCenter Extension Parish Office.


Download here: Louisiana Home Lawn Series: Purple Nutsedge 3624-J

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The LSU AgCenter and the LSU College of Agriculture

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