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Accepted manuscript

Interaction of glyphosate with auxin herbicides for control of Benghal dayflower (Commelina Benghalensis) at advanced growth stages

Published online by Cambridge University Press:  19 March 2025

Willian F. Larini*
Affiliation:
PhD Student, Federal University of Paraná, Curitiba, Paraná, Brazil
Alfredo Junior P. Albrecht
Affiliation:
Professor, Federal University of Paraná, Palotina, Paraná, Brazil
Debora C. Neuberger
Affiliation:
Undergraduate student, Federal University of Paraná, Palotina, Paraná, Brazil
Arthur A. M. Barroso
Affiliation:
Professor, Federal University of Paraná, Curitiba, Paraná, Brazil.
Leandro P. Albrecht
Affiliation:
Professor, Federal University of Paraná, Palotina, Paraná, Brazil
*
Author for correspondence: Willian Felipe Larini, Federal University of Paraná, n.1540, 80035-050, Curitiba, Paraná, Brazil., E-mail: [email protected]
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Abstract

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Auxinic herbicides are the second most used in Brazil, often combined with glyphosate in pre-plant burndowns management. However, their efficacy against Benghal dayflower at advanced growth stages remains poorly understood. Two field experiments were conducted in 2021 and 2022 on no-till fields naturally infested with Benghal dayflower at an advanced growth stage (∼50 cm height, 100% soil coverage) to evaluated the control efficacy of 2,4-D at 966 g ae ha-1, triclopyr at 720 g ae ha-1, fluroxypyr at 400 g ae ha-1 and dicamba at 720 g ae ha-1, combined or not with glyphosate (1,550 g ae ha-1). Dicamba was also tested at rates from 288 to 1,008 g ae ha⁻¹. Results indicate Benghal dayflower exhibits variable responses to auxin herbicides, influenced by both chemical family and the herbicide molecule. None of the treatments provided complete control at 8 wk after application (WAA). The highest visible control (∼77%) and dry mass reduction (∼57%) were provided by triclopyr (isolated or combined with glyphosate) and 2,4-D (combined with glyphosate), followed by fluroxypyr (isolated or combined with glyphosate) and 2,4-D (isolated), providing ∼69% visible control and 54% dry mass reduction. Even when statistical differences were detected by adding glyphosate to auxin herbicides, these differences were not sufficient to characterize a synergistic effect or improve control consistency. Dicamba (isolated or combined with glyphosate) provided the lowest control (∼54%) and dry mass reduction (∼30%). Additionally, dicamba doses up to 1008 g ae ha⁻¹ did not provide complete control (∼60% visible control and 51% dry mass reduction), suggesting that dicamba limitations cannot be mitigated through dose increase. By highlighting the challenges in controlling Benghal dayflower at advanced growth stages, these results emphasize the importance of early-stage weed control and the need to carefully assess which auxin herbicides to use and when glyphosate mixtures are necessary.

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