Yellow nutsedge is now one of the most common weeds in turf. Even though all textbooks say it thrives in wet areas, some of our worst yellow nutsedge infestations occur in dry years when turf thins. Though yellow nutsedge acts like an annual, it is technically a perennial surviving from tubers year to year. Tubers germinate and plants emerge in mid- to late May, mature throughout the summer if left untreated, begin forming new tubers in July after the summer solstice or once daylength returns to 14 hours, and then the above-ground portion of the plant dies with frost. Yellow nutsedge tubers may lay dormant in the soil for years and can germinate multiple times in a season if the original emerging plant does not survive (due to late frost, early herbicide applications, hand-pulling etc.). Add to this waxy leaves and a rhizome system that does not translocate herbicides effectively, and yellow nutsedge becomes one of the most difficult to control weeds that we have in the northern Great Plains. Cultural controls always help, so mowing at the highest practical height for the turf area, irrigation to prevent summer thinning, and aggressive fall fertilization to maximize density are all important. Postemergence herbicides include Basagran or SedgeHammer or ProSedge (formerly Manage), and FMC’s Dismiss (sulfentrazone). Since yellow nutsedge can regrow from rhizomes or tubers, multiple applications are usually needed and the problem will likely persist for multiple years. More information on biology and preemergence control can be found at http://turf.unl.edu/pdfctarticles/aprilYNSbiologyroch.pdf and http://turf.unl.edu/pdfcaextpub/LCOProyellownutsedge2012c.pdf.
We are starting a new research program on yellow nutsedge, looking at application timing, biology, turf competition effects, etc. Last year’s preliminary research showed almost surprisingly good control, especially with SedgeHammer and regardless of application timing. These treatments were applied on thin turf so excellent spray coverage was achieved. Data from a single year’s research may not reflect long term results and data will be recorded throughout this year to determine long-term control. Learn more about yellow nutsedge control at this year’s NTA Field Day on July 23, and registration information is at http://turf.unl.edu/2014NETurfAssociationAttendees.pdf .
Zac Reicher, Professor of Turfgrass Science, email@example.com