Glyphosate-resistant giant ragweed is one of the most competitive weeds of agronomic crops in the United States. Early emergence and rapid growth rate makes giant ragweed a competitive weed early in the season and reduces crop yields. Therefore, early spring control of giant ragweed using a preplant herbicide is critical. Glufosinate is an alternative POST herbicide for weed control in glufosinate-resistant soybean. Field experiments were conducted at David City, NE, in 2012 and 2013 to evaluate the efficacy of preplant herbicides followed by glufosinate applied alone or in tank mixes for control of glyphosate-resistant giant ragweed in glufosinate-resistant soybean. Preplant treatments containing 2,4-D, flumioxazin, glufosinate, paraquat, saflufenacil, and sulfentrazone provided 79 to 99% control of giant ragweed 21 d after treatment (DAT), and subsequent application of glufosinate alone or in tank mixes resulted in 90 to 99% control at 21 DAT. Preplant application of S-metolachlor plus metribuzin or chlorimuron, flumioxazin plus thifensulfuron followed by glufosinate resulted in < 40% control of giant ragweed, and soybean yields were < 870 kg ha−1. Although statistically comparable to several other treatments, preplant application of 2,4-D or saflufenacil tank mixes followed by glufosinate resulted in the highest level of control (> 97%) and soybean yield (2,624 to 3,378 kg ha−1). This study confirms that preplant herbicide options are available for control of glyphosate-resistant giant ragweed, and a follow-up application of glufosinate will provide season-long control in glufosinate-resistant soybean.
Nomenclature: 2,4-D amine; acetochlor; chlorimuron; cloransulam; dimethenamid-P; flumioxazin, fomesafen; glufosinate; glyphosate; imazethapyr; lactofen; metribuzin; paraquat, S-metolachlor; saflufenacil; sulfentrazone; thifensulfuron-methyl; giant ragweed, Ambrosia trifida L.; soybean, Glycine max (L.) Merr.
Ambrosia trifida resistente a glyphosate es una de las malezas más competitivas en cultivos agronómicos en Estados Unidos. Su emergencia temprana y tasa rápida de crecimiento hacen A. trifida una maleza competitiva temprano durante la temporada de crecimiento, y que reduce el rendimiento de los cultivos. De esta forma, el control de A. trifida, temprano en la primavera, usando herbicidas pre-siembra es crítico. Glufosinate es un herbicida POST alternativo para el control de malezas en soya resistente a glufosinate. Se realizaron experimentos de campo en David City, Nebraska, en 2012 y 2013 para evaluar la eficacia de herbicidas pre-siembra seguidos de glufosinate aplicado solo o en mezclas en tanque para el control de A. trifida resistente a glyphosate, en soya resistente a glufosinate. Los tratamientos pre-siembra con 2,4-D, flumioxazin, glufosinate, paraquat, saflufenacil, y sulfentrazone brindaron 79 a 99% de control de A. trifida 21 d después del tratamiento (DAT), y la subsecuente aplicación de glufosinate solo o en mezclas en tanque resultaron en 90 a 99% de control a 21 DAT. La aplicación pre-siembra de S-metolachlor más metribuzin o chlorimuron, flumioxazin más thifensulfuron seguidos de glufosinate resultaron en <40% de control de A. trifida, y los rendimientos de la soya fueron <870 kg ha−1. Aunque fue estadísticamente comparable a otros tratamientos, la aplicación pre-siembra de mezclas en tanque de 2,4-D o saflufenacil seguidas de glufosinate resultaron en el mayor nivel de control (>97%) y el mayor rendimiento de la soya (2,624 a 3
