Sesame Tolerance to Herbicides Applied Postemergence-Directed

Aims: Studies were conducted to determine sesame tolerance to herbicides applied postemergence-directed (PDIR) to the lower 5 and 15 cm of the stem.

Study Design: Randomized complete block design with a 14 (herbicide) x 2 (spray height) factorial arrangement with 3 replicates.

Place and Duration of Study: In south Texas near Uvalde and in the Texas High Plains near Lorenzo between May 2006 and November 2007.

Methodology: Herbicides included carfentrazone-ethyl at 0.02 kg/ha, glufosinate-ammonium at 0.58 kg/ha, glyphosate at 0.84 kg/ha, lactofen at 0.22 kg/ha, linuron at 1.12 kg /ha, paraquat at 0.28 kg/ha, propazine at 1.12 kg/ha, pyraflufen-ethyl at 0.002 kg/ha, pyrithiobac at 0.07 kg/ha, trifloxysulfuron-sodium at 0.008 kg/ha, trifloxysulfuron-sodium at 0.008 kg/ha plus prometryn at 1.12 kg/ha, linuron at 0.56 kg/ha plus diuron at 0.56 kg/ha, glyphosate at 0.84 kg/ha plus prometryn at 1.12 kg/ha, and glyphosate at 0.84 kg/ha plus diuron at 1.12 kg/ha. Herbicides were applied when sesame was < 76 cm tall with one spray tip on each side of the row adjusted to spray a PDIR band to the lower 5 to 15 cm of the stem.

Results: Glyphosate at 0.84 kg/ha and pyrithiobac at 0.07 kg/ha resulted in 28 to 90% stunting when applied to lower 15 cm of the stem. Glyphosate applied to lower 15 cm and pyrithiobac applied to the lower 5 and 15 cm consistently reduced sesame yield (51 to 89%) when compared with the control. Glufosinate-ammonium and the premix of linuron plus diuron applied to the lower 5 cm caused the least sesame stunting (< 8%) and only linuron plus diuron resulted in a reduction in yield at one location when compared with the non-treated.

Conclusion: Sesame injury was greatest when herbicides were applied to the lower 15 cm of the stem compared to 5 cm applications