Controlling Glyphosate-Resistant Palmer Amaranth (Amaranthus palmeri) in Cotton with Resistance to Glyphosate, 2, 4-D, and Glufosinate. (June 2014)

• Record Type: Journal Article
• Authors: Merchant, Rand M.; Culpepper, A. Stanley; Eure, Peter M.; Richburg, John S.; Braxton, L. Bo
• Is Part Of: Weed technology. Volume 28:Number 2(2014)
• Page Start: 291
• Page End: 297
• Publication Date: 2014-06
• Subjects: 2, 4-D, -- 2, 4-DB, -- diuron, -- glufosinate, -- glyphosate, -- MSMA, -- Palmer amaranth, Amaranthus palmeri (S.) Wats. AMAPA, -- cotton, Gossypium hirsutum L.; Resistance management, -- tank mixtures, -- sequential herbicide applications; Weeds -- Periodicals; Weeds -- Control -- Periodicals; 632.5
• DOI: 10.1614/WT-D-13-00104.1
• Languages: English
• ISSNs: 0890-037X

Abstract

Abstract : Field experiments were conducted in Macon County, Georgia, during 2010 and 2011 to determine the impact of new herbicide-resistant cotton and respective herbicide systems on the control of glyphosate-resistant Palmer amaranth. Sequential POST applications of 2, 4-D or glufosinate followed by diuron plus MSMA directed at layby (late POST-directed) controlled Palmer amaranth 62 to 79% and 46 to 49% at harvest when the initial application was made to 8- or 18–cm-tall Palmer amaranth, in separate trials, respectively. Mixtures of glufosinate plus 2, 4-D applied sequentially followed by the layby controlled Palmer amaranth 95 to 97% regardless of Palmer amaranth height. Mixing glyphosate with 2, 4-D improved control beyond that observed with 2, 4-D alone, but control was still only 79 to 86% at harvest depending on 2, 4-D rate. Sequential applications of glyphosate plus 2, 4-D controlled Palmer amaranth 95 to 96% following the use of either pendimethalin or fomesafen. Seed cotton yield was at least 30% higher with 2, 4-D plus glufosinate systems compared to systems with either herbicide alone. The addition of pendimethalin and/or fomesafen PRE did not improve Palmer amaranth control or yields when glufosinate plus 2, 4-D were applied sequentially followed by the layby. The addition of these residual herbicides improved at harvest control (87 to 96%) when followed by sequential applications of 2, 4-D or 2, 4-D plus glyphosate; yields from these systems were similar to those with glufosinate plus 2, 4-D. Comparison of 2, 4-D and 2, 4-DB treatments confirmed that 2, 4-D is a more effective option for the control of Palmer amaranth. Results from these experiments suggest cotton with resistance to glufosinate, glyphosate, and 2, 4-D will improve Palmer amaranth management. At-plant residual herbicides should be recommended for consistent performance of all 2, 4-D systems across environments, although cotton with resistance to glyphosate, glufosinate, and 2, 4-D will allow greater flexibility in selecting PRE herbicide(s), which should reduce input costs, carryover concerns, and crop injury when compared to current systems.