Extension Educator, Horticulture
Some plants have done particularly well this summer. A wet spring and early summer brought the invasion of the yellow nutsedge according to the U of I Home, Yard and Garden Pest Newsletter.
Yellow nutsedge, also known as yellow nutgrass, is a warm season perennial in the sedge family. Sedges look like grasses, but if you roll the stem of sedges between your fingers you will notice they are three sided. Grass stems are round or flattened. Yellow nutsedge is native to Illinois and many parts of North America.
Nutsedge is often considered troublesome when it appears in lawns. It is a lighter green and grows faster in hot weather than our lawn grass.
Nutsedge has upright, light yellow-green leaves 1/8 to 1/2 inch wide and up to three feet long. They have parallel veins with a prominent midvein. Leaves grow rapidly in summer often appearing well above the lawn grass. Nutsedge has a fibrous root system. It also develops horizontal underground stems (rhizomes) with white tubers (nutlets) forming on the ends of the rhizomes.
Tubers develop rapidly six to eight weeks after the plants emerge usually during late July and August. Nutlets may get to be almost an inch in diameter. Unfortunately the nutlets may persist in the soil for many years. New plants emerge from the nutlets from late May to mid-July.
Yellow nutsedge is often an indicator of poor drainage. It particularly likes wet or moist sites or sites heavily irrigated. However it can grow in all soil types and can tolerate dry sites once it's established.
Yellow nutsedge is difficult to control especially once it has formed tubers. If you want to control it, don't wait. Once it has formed tubers, pulling it out will only remove the original plant.
To control nutsedge without chemicals, maintain a thick stand of lawn grass through proper maintenance. A maintenance schedule is available throughthe University of Illinois Extension Offices. Pull nutsedge plants soon after emergence before nutlets can form. Modify drainage in moist or wet areas. Check for nutlets in purchased soil or mulch.
If herbicides are chosen as the control option, there are several available to be used in lawns once the nutsedge emerges. However herbicides often will not give total control and multiple applications may be necessary. Herbicides for nutsedge control are generally applied from mid-summer to mid-fall. Commercial turfgrass managers may use Basagran (bentazon) or herbicides containing MSMA. Home gardeners should look for herbicides specifically formulated for nutsedge control. Ortho as well as other companies make a crabgrass and nutgrass killer. Always read, understand and follow the label directions.
Misapplied herbicides can damage desirable plants. To reduce the chances of damage:
Watch wind speeds to avoid drift. Often early mornings are less windy than later in the day.
Apply herbicides when air temperatures are between 65 and 85 degrees F.
Do not apply herbicides when precipitation is expected within 24 hours.
Do not mow for a few days prior to or following application.
When possible, to reduce unnecessary pesticide use, make spot treatments rather than treating large areas.