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Yellow Nutsedge

Yellow Nutsedge (Cyperus esculentus L.) is a common weed found in many home lawns. The color, growth habit, and rapid growth rate make yellow nutsedge a prominent distraction in the aesthetics of high quality lawns.

Yellow nutsedge is a warm season perennial plant. The above ground foliage does not survive cold winters. However, as soils warm during the late spring and early summer period, germination of tubers and seed produced by plants from previous years are capable of producing new yellow nutsedge plants. Heavy infestations of this weed in lawns and other turfgrass areas usually become readily apparent in July and August.

Identifying yellow nutsedge

Early detection is crucial. Luckily, yellow nutsedge is fairly easy to identify. It grows 6" — 2-1/2' tall. Stems are erect, triangular-shaped and yellow-green in color. Most of the leaves grow from the base of the stem. Leaves are produced in groups of three. They are linear, have a prominent midrib and waxy covering, and taper to a point. Flowers are yellowish-brown and look like a series of spikes.

The plants have branched fibrous roots. Reproduction is primarily by the popcorn kernel-sized tubers that can remain viable for 10 or more years. It also produces seeds.

Yellow nutsedge is most easily identified by the triangular shape of the stem. If you roll the stem of the plant in your fingers, you should be able to feel the triangular shape.

Yellow nutsedge grows most actively during the hot months of summer. Often the leaves of yellow nutsedge will grow 2" — 4" above the turf grass. During spring and fall, when temperatures are cooler and growth is slower, yellow nutsedge is not as easily noticed.

Nutsedge Control

Control is difficult and should be started as soon as plants are discovered. One-shot weed control will not work, and multiple applications will be necessary. Traditional annual grass weed or broadleaf weed control products will not control yellow nutsedge. Specific herbicides are required for control. Herbicides are most effective on young, actively growing plants.

Nutsedge is difficult to control culturally because it produces numerous tubers that give rise to new plants. Pulling nutsedge often increases the number of plants because dormant tubers are activated. However, small stands of nutsedge can be controlled by persistent pulling. Pulling will eventually weaken the plants and cause them to die out.

Herbicides may be required when large patches of nutsedge are present in the turf area. For homeowners, a herbicide containing methanearsonate (this material may slightly discolor Kentucky bluegrass, but no serious injury should result if used at the rate and under the conditions described on the label). This is often sold under trades names like “Crabgrass Killer.” Consider the following steps in order to be successful in reducing the nutsedge contamination.

1. Be sure to read and follow all directions on the herbicide label.

2. One day before making the herbicide application, irrigate the turf area to moisten the soil profile to a depth of 6". This will help the herbicide reach the roots and the small nuts.