Using Quinclorac to Control Annual Grasses and Palmer Amaranth in Grain Sorghum (Sorghum bicolor L.)


  • James Grichar Texas A&M AgriLife Research and Extension Center, Corpus Christi, TX 78406
  • Travis Janak B-H Genetics, 5933 FM 1157, Ganado, TX 77962



yield, Texas millet, postemergence, Palmer amaranth, Broadleaf signalgrass


Field studies were conducted during the 2015 and 2016 growing seasons in south-central Texas to determine control of Palmer amaranth and annual grasses along with grain sorghum tolerance to quinclorac alone and in various combinations when applied to weeds < 5 cm (EPOST) or 10 to 16 cm tall (LPOST). When evaluated late-season quinclorac alone at 0.43 kg ae ha-1 controlled broadleaf signalgrass 72% when applied EPOST and 91% when applied LPOST. Combinations of quinclorac with either atrazine, pyrasulfotole + bromoxynil, dicamba, or dimethenamid-P controlled Palmer amaranth 88 to 100% when applied EPOST or LPOST; however, broadleaf signalgrass control with these combination was better when applied LPOST (75 to 95%) compared with EPOST (37 to 72%) applications. Texas millet control with quinclorac was poor in both years and was never greater than 54%. Quinclorac plus either atrazine, pyrasulfotole + bromoxynil, dicamba, or atrazine + dimethenamid-P caused at least 20% sorghum injury at one of three locations. No yield reductions from the untreated check were noted in either year; however, in 2016 all treatments with the exception of quinclorac alone at 0.29 kg ha-1 applied EPOST, quinclorac + pyrasulfotole + bromoxynil applied LPOST, quinclorac + atrazine + pyrasulfotole + bromoxynil applied LPOST, and quinclorac + dicamba at either application timing produced yields that were greater than the untreated check.


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How to Cite

Grichar, J., & Janak, T. (2021). Using Quinclorac to Control Annual Grasses and Palmer Amaranth in Grain Sorghum (Sorghum bicolor L.). JOURNAL OF ADVANCES IN AGRICULTURE, 12, 1–10.