Hostname: page-component-54dcc4c588-sdd8f Total loading time: 0 Render date: 2025-10-03T01:11:18.345Z Has data issue: false hasContentIssue false
Accepted manuscript

Full-season herbicide programs to control a seven-way-resistant Palmer amaranth accession under soybean technologies

Published online by Cambridge University Press:  25 September 2025

Pâmela Carvalho-Moore*
Affiliation:
Former Graduate Research Assistant, Department of Crop, Soil and Environmental Sciences, University of Arkansas, Fayetteville, AR, USA
Jason K. Norsworthy
Affiliation:
Distinguished Professor and Elms Farming Chair of Weed Science, Department of Crop, Soil and Environmental Sciences, University of Arkansas, Fayetteville, AR, USA
L. Tom Barber
Affiliation:
Professor and Extension Weed Scientist, Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Lonoke, AR, USA
Ingo Meiners
Affiliation:
Biology R & D Group Leader – Weed Control, BASF Corporation, Research Triangle Park, NC, USA
Aimone Porri
Affiliation:
Laboratory Head – Weed Resistance Research, BASF SE, Limburgerhof, Germany
*
Corresponding author: Pâmela Carvalho-Moore, University of Arkansas, 1354 W Altheimer Dr, Fayetteville, AR 72704 (pcarvalh@uark.edu)
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

A seven-way herbicide-resistant Palmer amaranth accession (MSR2) was identified in AR. Herbicide programs providing season-long control of this problematic accession need to be investigated, especially within the current soybean portfolio. Therefore, this study aimed to evaluate the efficacy of different soybean herbicide programs for controlling seven-way-resistant Palmer amaranth accession, MSR2, emphasizing the contribution of residual herbicides to full-season suppression. Field experiments were conducted in 2022 and 2023 in Fayetteville, AR, in an area infested by MSR2. A total of 14 herbicide programs were tested, targeting available soybean technologies that enable glyphosate, glufosinate, dicamba, and 2,4-D. All herbicide programs had one or two postemergence herbicides applied at early postemergence (EPOST) and late postemergence (LPOST). Additionally, eight herbicide programs included residual herbicides at preemergence (PRE; S-metolachlor plus metribuzin) and EPOST (S-metolachlor). A nontreated control was included for comparison. Visible Palmer amaranth control (%) was assessed at LPOST and 2 weeks after LPOST (2 WA LPOST). Palmer amaranth plants were counted from two 0.25 m2 quadrats randomly marked at each evaluation, and the density reduction (%) was calculated compared to the nontreated control. Preplanned orthogonal contrasts were conducted to compare herbicide programs with or without residual herbicides. Overall, in both years, the highest MSR2 control at both evaluations was observed in the herbicide programs that included residuals at PRE and EPOST with postemergence treatments of 2,4-D or dicamba (single or mixed). For Palmer amaranth density, herbicide programs that relied on residuals at PRE and EPOST with sequential postemergence applications of 2,4-D plus glufosinate or dicamba plus glyphosate obtained higher reduction levels. Findings reveal that the addition of residual herbicides is crucial in controlling multiple-herbicide-resistant Palmer amaranth biotypes, like MSR2. Herbicide programs based solely on postemergence applications were ineffective in controlling accession MSR2.

Information

Type
Research Article
Creative Commons
Creative Common License - CCCreative Common License - BYCreative Common License - NCCreative Common License - ND
This is an Open Access article, distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives licence (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is unaltered and is properly cited. The written permission of Cambridge University Press must be obtained for commercial re-use or in order to create a derivative work.
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Weed Science Society of America