New England Blade – Randy Prostak, Extension Weed Specialist, University of Massachusetts
Yellow nutsedge is a member of the family Cyperaceae, or sedge family. Also known as nutgrass, yellow nutsedge is commonly considered to be one of the most troublesome and “difficult-to-manage” weeds of turf and landscape. While this weed is a monocot like grasses, it is not a grass. Despite it being tossed in the “difficult-to-manage” category, yellow nutsedge with proper product selection and application timing can be managed successfully.
Life cycle and description: Yellow nutsedge is a perennial sedge reproducing by tubers (nutlets) at the end of short, scaly rhizomes and rarely from seed. While yellow nutsedge can occur in dry soils, it is frequently more aggressive in wet areas. These areas may be wet due to poor drainage and/or overwatering.
Upright, triangular stems arise from overwintering nutlets in very late spring and early summer. The triangular stems are the most useful identification characteristic, as you can feel the triangular shape by rolling the stem in your fingertips. Yellow nutsedge leaves are light green, glossy, with a prominent midrib and taper to a sharp point. It is most noticeable in summer because its leaves grow more rapidly than the cool-season turf during the hottest summer months. During spring and fall, nutsedge growth is slower and not as easy to spot in turf. Yellow nutsedge produces a yellow to light brown seedhead, although they are seldom observed in frequently mown turf.
Cultural management strategies: The best method for controlling yellow nutsedge (and other weeds) is to encourage the growth of a healthy, dense, vigorous stand of turf that can compete with weeds. Encourage dense turf stands by following proper turf maintenance practices, including fertilization, proper irrigation, frequent mowing at the proper height and over-seeding as needed. Yellow nutsedge is most problematic in turf that is mown too short and in areas where soils remain moist from poor drainage and/or overwatering. In a landscape setting, physical removal of newly introduced plants can be utilized before yellow nutsedge has a chance to take a foothold.
Herbicide management strategies: Cultural management strategies will slow the spread of yellow nutsedge; however, a larger established population will usually require the use of an herbicide program. Several herbicides are available for the control of yellow nutsedge. Regardless of herbicide selected, yellow nutsedge is a “difficult-to-control” weed that may require multiple herbicide applications over two or more years. Late spring to early summer is the best time to control yellow nutsedge because plants will not have started producing tubers (nutlets), making it easier to manage with herbicides. Since the nutlets are the plants’ primary survival structure, it is important to control yellow nutsedge early in the summer before it produces nutlets. Patience and diligence are required for the successful management of yellow nutsedge. Two to three years of control using herbicides are sometimes required to reduce viable tubers in the soil. Herbicides often injure or only partially control growing yellow nutsedge plants and help prevent more nutlets from forming, but herbicide applications will not control nutlets that are viable in the soil but have not yet produced plants. Table 1 provides a list of herbicides that are available for yellow nutsedge management.