Yellow Nutsedge
Click for larger image Yellow nutsedge (Cyperus esculentus) in flower

Yellow nutsedge, Cyperus esculentus, is a common lawn and garden weed in Missouri. It is also referred to as nutgrass or watergrass. It is not a grass but rather a sedge. This is evident in the stem that is triangular in cross section, not round as in grasses. The leaves are bright green and have a waxy appearance. It grows faster than many lawn grasses so it is often noticed when it outgrows the surrounding grass. It will also remain a bright green in summer when surrounding lawn grass may be a lighter green. It thrives in low spots and high moisture areas that drain poorly, but can occur in drier sites as well. The plant produces feathery, umbrella-like flower clusters. The plant is perennial, reproducing by seed and underground tubers. The underground tubers or nutlets can remain dormant in the ground for several years.

Integrated Pest Management Strategies

In Lawns

1. Pulling the plants when they are young can give temporary control. Pulling will not, however, remove the underground nutlets so it is not a cure. Increasing the health of the lawn by mowing high, aerating, and fertilizing in the fall can help the grass better compete with nutsedge. Be sure to remove plants in the lawn and adjacent areas before they go to seed. Warmseason grasses compete better with nutsedge than do cool-season grasses.

2. Treat with an herbicide. Ortho Crabgrass & Nutgrass Killer and Basagran are effective. Follow label directions and observe precautions. Two to three applications 4–7 days apart are generally required. Spot treat only the areas that have nutsedge. To prevent future problems, improve the health of the lawn to better compete with germinating nutsedge. An herbicide called Sedgehammer (Manage) provides the most effective control, but has limited availability.

In Planting Beds

1. Dig plants.In planting beds, dig nutsedge plants and remove the underground nutlets. Regular pulling will be necessary to effect control.

2. Spot treat with a chemical herbicide. Spot treatment with glyphosate (Roundup, Kleenup) gives good control. glyphosate (Roundup, Kleenup) will kill plants, root and all. It is nonselective and will kill or injure most plants it contacts. Use with care around desirable plants.

Organic Strategies

In lawns:  Strategy 1 is a strictly organic approach.

In planting beds:  Strategy 1 is a strictly organic approach.

More images:

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Triangular stem of yellow nutsedge (Cyperus esculentus) in cross-section ; a characteristic of all sedges
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Unusual seed head of yellow nutsedge (Cyperus esculentus)
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Yellow nutsedge (Cyperus esculentus) in a flower bed
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Yellow nutsedge (Cyperus esculentus) in a lawn
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Yellow nutsedge (Cyperus esculentus) in a dormant lawn
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Close-up of the clusters of feathery spikelets (flower clusters) of yellow nutsedge (Cyperus esculentus)
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Seed head of yellow nutsedge (Cyperus esculentus)
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Seed head of yellow nutsedge (Cyperus esculentus)
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