Publications - Faculty - Recently Submitted Faculty Publications 2008
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Singh - Weed Technology
Effect of Ammonium Sulfate and Adjuvants on the Efficacy of Glyphosate
M. Singh and Shiv D Sharma
Abstract. A study was conducted to examine the effect of ammonium sulfate (AMS) applied with and without an adjuvant on the efficacy of glyphosate. Herbicide treatments were applied to broadleaf weeds—Brazil pusley (Richardia brasiliensis), Spanish needles (Bidens pilosa), Florida beggarweed (Desmodium tortuosum) and pigweed (Amaranthus retroflexus), and grassy weeds—guineagrass (Panicum maximum), Johnsongrass (Sorghum halepense), and crowfootgrass (Dactyloctenium aegyptium). The percent control of both weed types were significantly higher with the incorporation of AMS or the adjuvant, or the adjuvant plus AMS to 370 g a.i./ha glyphosate over no adjuvant or AMS. Percent control of grass weeds with the addition of any one of the adjuvant achieved 100% control except with glyphosate + L-77, where percent control of guineagrass and Johnsongrass was only 82% and 85%, respectively, 1 week after treatment (WAT). Brazil pusley plants started recovering from the phytotoxic effects at 3 WAT. Percent control of Brazil pusley was significantly reduced at 3 WAT with glyphosate + adjuvant, and glyphosate + adjuvant + AMS. However, when glyphosate + AMS was applied, the reduction in percent control of Brazil pusley was significantly less as compared to other treatments. Percent control of Spanish needles increased with time and was highest at 3 WAT. At 3 WAT, complete control of Florida beggarweed, pigweed, and all grasses, was achieved under all the treatments. Study showed the additional beneficial effect of adding AMS to glyphosate + adjuvant application.
