Driving Homeowners ‘Nuts – Sedge’ in the Lawn
Do you have ‘grass patches’ that grow twice as fast as your turf during the summer, even during the hottest weather? You likely are combating yellow nutsedge, a common warm-season lawn weed across Virginia. Sedges are easily identified by their triangular stem and overall triangle shape when peered upon from above. They emerge in Virginia in June and remain until frost when they enter winter dormancy. Yellow nutsedge grows by rhizomes and tubers which makes control difficult.
Cultural Control: Nutsedges thrive in moist areas and their presence often indicates poor drainage, too frequent irrigation or leaky sprinklers. Once established, however, they will tolerate normal moisture levels or even drought. Give turfgrasses a competitive advantage by following recommended practices for your lawn grass including mowing at the ideal height, applying fertilizer at the proper rate and time, and maintaining the ideal soil pH. Proper irrigation is especially important, since moist soil will encourage the growth of nutsedge. Monitor and manage insect and disease infestations to avoid thin, bare areas that may be overtaken by nutsedge.
Mechanical Control: It is possible to eliminate small patches of nutsedge by digging. Dig at least 10 inches deep and at least eight to ten inches beyond the diameter of the above ground leafy portion of the plant. This will ensure removal of the spreading tubers. This is best done early in the spring before more tubers are produced.
Chemical Control: Nutsedges can be controlled with postemergence herbicides. Check the label to make sure the chemical you choose will not damage desired plants growing around the nutsedge. Apply herbicides when nutsedge is actively growing in warm conditions with adequate soil moisture. Water the lawn the day before spraying to help protect the turfgrass and to assure that the weeds are actively growing so they will better take up the herbicide. Avoid applications during hot or dry weather (> 90 °F) to minimize the chances of injury to the turfgrass. Avoid mowing before a postemergence herbicide application to allow for adequate foliage to absorb the herbicide. Also avoid mowing for two days after application to allow time for the plant to absorb and move the herbicide down to the tubers. Try to gain control of sedges early in the season. Late in the season the plant begins to concentrate on producing seed instead of storing carbohydrates in its rhizomes and tubers and this general change in ‘flow direction’ means it is harder to get the herbicide to the below-ground structures in sufficient quantity to kill the plant. There are four primary herbicides available for sedge control in the homeowner market. The active ingredients to look for on the herbicide label are: bentazon, halosulfuron, imazaquin, or sulfentrazone. The most recent product that controls the widest spectrum of sedges is sulfentrazone, but halosulfuron, imazaquin and bentazon have been staples for many years in targeting this weed.
Expect nutsedge control even under ideal conditions to require more than a single application. Always follow the label directions for any pesticide to protect yourself, others, and the environment. And remember that your local extension office is a great resource for information specific to your location.