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Accepted manuscript

SELECTIVITY AND EFFICACY OF TERBUTHYLAZINE AS AN ALTERNATIVE HERBICIDE APPLIED ALONE OR IN COMBINATION FOR THE CONTROL OF WEEDS IN WHEAT

Published online by Cambridge University Press:  17 December 2025

Leandro Galon
Affiliation:
Associate Professor, Department Agronomy, Federal University of Fronteira Sul, Erechim, RS, Brazil
Érica Maria Hojnowski
Affiliation:
Student, Faculty of Agronomy, Department Agronomy, Federal University of Fronteira Sul, Erechim, RS, Brazil
Gilson Lucas Müller
Affiliation:
Student, Faculty of Agronomy, Department Agronomy, Federal University of Fronteira Sul, Erechim, RS, Brazil
Douglas Alessandro Haboski
Affiliation:
Student, Faculty of Agronomy, Department Agronomy, Federal University of Fronteira Sul, Erechim, RS, Brazil
Gabrieli Enge Zamboni
Affiliation:
Student, Post Graduation Program in Environmental Science and Technology of the Federal University of Fronteira Sul, Erechim, RS, Brazil
Germani Concenço
Affiliation:
Researcher, Laboratory of Sustainable Cropping Systems, Embrapa Temperate Agriculture, Pelotas, RS, Brazil.
Gisele Bigolin
Affiliation:
Student, Faculty of Agronomy, Department Agronomy, Federal University of Fronteira Sul, Erechim, RS, Brazil
Letícia Bampi
Affiliation:
Associate Professor, Department Agronomy, Federal University of Fronteira Sul, Erechim, RS, Brazil
André Andres
Affiliation:
Researcher, Laboratory of Sustainable Cropping Systems, Embrapa Temperate Agriculture, Pelotas, RS, Brazil.
Gismael Francisco Perin
Affiliation:
Associate Professor, Department Agronomy, Federal University of Fronteira Sul, Erechim, RS, Brazil
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Abstract

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Herbicides are commonly used for weed control in wheat production due to their effectiveness, speed, and lower cost compared to other management methods. This study aimed to evaluate the selectivity and efficacy of herbicides applied alone or in combination for controlling major weed species infesting wheat. Field experiments were conducted in 2022 and 2023 using a randomized complete block design with four replications. Terbuthylazine (500 and 750 g ha-1) + adjuvant, carfentrazone-ethyl (120 g ha-1), saflufenacil and pyraflufen-ethyl (3.75 and 5 g ha-1) + clodinafop-propargyl caused the highest phytotoxicity to wheat. The best wheat physiological performance (internal CO2 concentration, photosynthesis and transpiration rates, stomatal conductance, water use, and carboxilation efficiencies) was observed with terbuthylazine (750 g ha-1), carfentrazone-ethyl (80 g ha-1), 2,4-D, and terbuthylazine + clodinafop-propargyl (750 + 96 g ha-1). Terbuthylazine (500 and 750 g ha-1) and pyraflufen-ethyl (3.75 and 5 g ha-1) combined with clodinafop-propargyl (96 g ha-1), provided the most effective control of wild radish and ryegrass and resulted in the highest grain yields. Regarding the grain yield components of wheat (number of plants per meter, number of spikes, spike length, number of filled and sterile grains, hectoliter weight, thousand-grain mass, and grain yield), the weed-free control and the treatment with terbuthylazine + clodinafop-propargyl (750 + 96 g ha⁻¹) showed the best performance. In the absence of weed control, average grain yield losses reached 91%. The herbicides terbuthylazine and pyraflufen-ethyl demonstrated potential for the control of broadleaf weeds, such as wild radish, which exhibit resistance to acetolactate synthase inhibitors, and where 2,4-D is less effective under low-temperature conditions. However, further studies using commercial formulations, adjuvants, and varietal tolerance tests are required to validate the use of these herbicides in wheat in Brazil.

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