The following is a repost of an article that I wrote on nutsedge control in turf and landscapes. Wet weather will increase infestations of this weed.
Yellow nutsedge (Cyperus esculentus) is a troublesome sedge weed in turf and landscape beds, particularly in irrigated and wetter areas. Heavier nutsege infestations will occur in wet years. It has shiny, yellow-green grass-like leaves, a triangular stem (characteristic of sedges as a group) and, if kept un-mowed, will produce a yellow-brown seed head cluster. It spreads by rhizomes and produces tubers that are formed at the end of these rhizomes. One plant can produce up to 700 tubers in a season. Tubers have buds that will send out new shoots following a dormancy period (cold required). Tuber sprouting is promoted by high soil moisture conditions. Viable seeds may also be produced. Yellow nutsedge tolerates light shade and medium mowing heights. It can grow through plastic mulch and may come through landscape fabric. Nutsedge is often introduced into a landscape through tuber infested soils carried with planting material (such as B&B plants).
Control of established patches of yellow nutsedge can be difficult. Hand digging is ineffective unless all tubers are removed from the soil. Tillage and hoeing often promotes nutsedge spread by moving tubers around and cutting tubers that will result in multiple plants being produced. Mulch can suppress nutsedge; however some nutsedge plants can grow through the mulch. Moisture control (keeping areas dry) will limit nutsedge emergence but will not work in irrigated areas. Fortunately, there are several herbicides that are effective on nutsedge. Metolachlor applied preemergence has provided good control in landscape beds. Halsulfuron applied post emergence has provided excellent control in established woody landscape plantings and in turf. Sulfentrazone gives excellent post emergence yellow nutsedge control in turf and is effective against many other sedges (annual and perennial) such as Kyllinga. Bentazon can be used over the top for nutsedge control in established turf and some ornamentals and as a directed spray in most landscape situations. Two applications are generally needed for best control. Glyphosate (directed, wiper, or spot spray applications) can also control nutsedge; however 2 or more applications are often needed.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County