World of Weeds: Yellow nutsedge
Yellow nutsedge (Cyperus esculentus) is the feature of this month’s World of Weeds article. Several questions have come in recently regarding identification and control of yellow nutsedge (also called chufa, field nutsedge, ground almond, or yellow nutgrass, among others), as well as other sedge species. This article will focus on the ecology and management of yellow nutsedge, but will also mention some of the other sedges found in Kansas.
Ecology of yellow nutsedge
Numerous sedge species are found throughout Kansas. Most are categorized in the genus Cyperus or Carex. Yellow nutsedge is among the more troublesome species and was introduced from Eurasia. Sedges are typically found in moist soils, and in some cases may be an indicator of poor soil drainage. Sedges are either annual or perennial plants. Yellow nutsedge is a perennial that reproduces primarily by tubers. Yellow nutsedge tubers are a food source for wildlife (notably ducks and turkey) and, in some places, humans. The name chufa is generally used for the plant when it is cultivated.
The key feature for sedges is a triangular stem. Most of the leaves come from the base of the plant and reach about the same height. Yellow nutsedge grows about 1 to 2½ feet tall (Figure 1). One of the features that distinguishes yellow nutsedge from others is that the leaves taper to a point (purple nutsedge leaves have relatively blunt tips). The yellowish-colored inflorescence (seed head) is a more distinguishing feature; many other sedges have darker inflorescences in shades of reddish-brown to reddish-purple. A yellow nutsedge inflorescence contains many spikelets that are around ½ to 1-inch long. Each spikelet contains many seeds contained in three-sided achenes (similar to a sunflower seed). There are a few leaf-like bracts immediately below the inflorescence. Yellow nutsedge tubers are brown and pea-shaped, about ½ to ¾ inch long (Figure 2). Individual tubers grow at the end of the rhizomes (purple nutsedge tubers grow in chains).
Figure 1. Clumps of yellow nutsedge infesting a soybean field (left) and a flowering plant (right). Photos by Dallas Peterson, K-State Research and Extension.
Figure 2. All sedges have triangular stems (left). Tubers are the primary way yellow nutsedge spreads (right). Photos by Bruce Ackely.
Yellow nutsedge is a difficult to control weed in agronomic crops, as well as in homeowner gardens, lawns, and flower beds. Research suggests corn yield can be reduced up to 50% and cotton yield by nearly 30% by yellow nutsedge. Tillage alone is not an effective control measure, nor is hand removal because the tubers are often not removed. Herbicides containing the active ingredient halosulfuron are among the best choices for nutsedge control. These products can be found under a variety of tradenames for various application sites. Dual, Outlook, and Harness/Warrant or similar products will suppress nutsedge when applied pre-emergence. Glyphosate also provides some control.
Stoller et al., 1979; Patterson et al., 1980.
Check out these other World of Weeds articles!
Palmer amaranth - https://bit.ly/2Wzl8BA
Kochia – http://bit.ly/2udtQK1
Common sunflower – http://bit.ly/2wSy8be
Stinging nettle – http://bit.ly/37nOqFC
Mistletoe - http://bit.ly/2QbmXQO
Stay tuned for the next World of Weeds article coming out soon! Feel free to send Dr. Lancaster or Kathy Gehl (firstname.lastname@example.org) an email if you have a special request for a future article.
Sarah Lancaster, Extension Weed Science Specialist