It's a perennial sedge, recognized by the triangular stems, rapid rate of summer growth, and light green color. Last summer's ample rainfall certainly helped nutsedge infestations. Although yellow nutsedge is well-known for its ability to colonize poorly drained or constantly wet areas, it will also flourish in hot, dry areas as well.
Yellow nutsedge germinates from seed or sprouts from tubers (often called "nutlets") that have overwintered. The plant grows quickly and develops rhizomes, which can initiate many "daughter plants" during the summer. New tubers develop at the tips of the rhizomes during the summer. When mature, the tubers separate from the rhizomes. Tubers can remain dormant in the soil for over 10 years just waiting to sprout. So nutsedge can spread by seeds, tubers (the overwintering structure), or rhizomes. Tubers and seeds can be transported with soil, mulch, water, animals, equipment carrying soil, and probably lots of other ways.
If herbicides are part of your arsenal, timing herbicide applications to reduce the development of tubers is important. Yellow nutsedge is most effectively treated before the tubers start to develop in mid-summer. That means using selective sedge herbicides earlier in the season than has commonly been done in the past. It may be earlier than your customers notice the problem. (Start now, not in August). Herbicide treatments aren't as effective once yellow nutsedge is big, spreading by rhizomes and developing tubers.
Removing plants before the 5-6 leaf stage prevents tuber formation and weakens tubers that have to re-sprout. Most post-emergent herbicides labeled for nutsedge specify applying around the 3 leaf stage of growth! Pre-emergent control of yellow nutsedge in turf is also possible using the product Eschelon. Turf managers that have tried it report that the pre-emergent helps reduce the amount of nutsedge that emerges and also slows or stunts the growth of plants that do emerge. Follow ups with post-emergent products are necessary.
The active ingredients effective on yellow nutsedge are listed below.
|Active ingredient||Example trade names||Timing||Label notes|
|Halosulfuron||Sedgehammer, Sedgehammer+, ProSedge||Postemergence: 3-8 leaf stage of growth.||Can make a second application 6 weeks after the first.|
|Imazosulfuron||Celero||Postemergence to established turf. After nutsedge reaches 3 leaf stage.||May need second treatment 3 weeks after first.|
|Mesotrione||Tenacity||Postemergence to young, actively growing weeds.||Make a second application 2 weeks after the first.|
|Sulfentrazone||Dismiss; Solitaire (combination of sulfentrazone + quinclorac)||Postemergence to established turf (new seedings after the second mowing.) 6 fl.oz./Acre rate of Dismiss is needed for nutsedge control (0.1875 lb/A sultentrazone)||For control, the amount of sulfentrazone is critical. Many combination products do not contain adequate rates of sulfentrazone for control.|
|Sulfentrazone||Eschelon (combination of sulfentrazone + prodiamine)||Premergent||Provides pre-emergent suppression or control of sedges. Use on well-established turf.|
So take some time to read the product labels to be sure about rates and timing. Also communicate with your customers about mowing and irrigation schedules to maximize herbicide performance. And think about starting earlier in the season.
Download product labels
Emerged nutsedge out-growing a summer lawn.
Aaron Patton, Dan Weisenberger. Turfgrass Weed Control for Professionals, 2014. Purdue University Publication AY-336-W.
University of Nebraska-Lincoln. April 27, 2010. Yellow Nutsedge: Identification, biology and management. Accessed online.