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. Pull young plant when they are young in late spring to early summer before they begin forming new tubers mid summer through fall. Pulling will not, however, remove the underground nutlets so it is not a cure. Dormant tubers can survive in the soil for up to 3 years and will require regular pulling to prevent new tubers from being formed. 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, Basagran and Tenacity are effective. The herbicide Sedgehammer (Manage) provides the most effective control, but has more limited availability. Follow label directions and observe precautions. Two to three applications 4–7 days apart are generally required to kill existing patches of nutsedge. Spot treat only the areas that have nutsedge but follow-up treating will need to be done for 2-3 years as dormant tubers sprout and grow.  Timing is also important. Treat beginning in late spring to early summer to kill plants before they begin forming new tubers, which occurs summer through fall.

To prevent future problems, improve the health of the lawn to better compete with germinating nutsedge.

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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Blades of yellow nutsedge, commonly called, water grass, bleached white from treatment with the herbicide Tenacity.
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To prevent yellow nutsedge from resprouting, these nutlets must be removed from the soil or killed with herbicide.
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Yellow nutsedge growing above the lawn grass.


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