Interaction of acetyl-CoA carboxylase enzyme inhibiting herbicides with auxin herbicides on ryegrass

This study aimed to evaluate the antagonistic effect of the mixture ofacetyl coenzyme-A carboxylase (ACCase) enzyme inhibiting herbicides and auxin herbicides in Lolium multiflorum and to determine mechanisms to mitigate this possible effect. The first experiments were conducted by associating the herbicide clethodim (108 g a.i. ha−1), quizalofop-p-ethyl (54 g a.i. ha−1), and clethodim + quizalofop-p-ethyl (108+54 g a.i. ha−1) with 2,4-D (1005 g a.e. ha−1) or triclopyr (720 g a.e. ha−1), in addition to the sole application of the respective graminicides. Another experiment included clethodim (54; 81; 108; 162; 216 g a.i. ha−1), quizalofop-p-ethyl (27; 40.5; 54; 81; 108 g a.i. ha−1), and clethodim + quizalofop-p-ethyl (54+27; 81+40.5; 108+54; 162+81; 216+108 g a.i. ha−1) mixed with 2,4-D (1005 g a.e. ha−1), or triclopyr (720 g a.e. ha−1), in addition to the control treatments without herbicide application. In the second experiment, herbicides clethodim (108 g a.i. ha−1), quizalofop-p-ethyl (54 g a.i. ha−1), and clethodim + quizalofop-p-ethyl (108+54 g a.i. ha−1) in combination with the herbicides 2,4-D (1005 g a.e. ha−1) or triclopyr (720 g a.e. ha−1)had malathion (1000 g a.i. ha−1) or glyphosate (720 g a.e. ha−1) mixed, in addition to the sole applications of the graminicides. The herbicide clethodim + quizalofop-p-ethyl did not present an antagonistic interaction with the auxin herbicides, and obtained 85% weed control. To obtain control similar to the sole application of this graminicide, the dose of the herbicide clethodim needs to be increased by 20%. However, the mixture of the herbicide quizalofop-p-ethyl with 2,4-D and triclopyr affects the ryegrass control. The use of strategies that increase the absorption of ACCase herbicides or the inhibition of P450 enzymes are ways to mitigate the antagonistic effect caused by the association of the two auxin herbicides. RESUMO: O objetivo do trabalho foi avaliar o efeito antagônico da mistura de herbicidas inibidores da enzima ACCase e herbicidas auxínicos em Lolium multiflorum e determinar mecanismos de mitigação deste possível efeito. No primeiro momento foram conduzidos experimentos associando o herbicida clethodim (108 g i.a. ha-1), quizalofop-p-ethyl (54 g i.a. ha-1) e clethodim + quizalofop-p-ethyl (108 + 54 g i.a. ha-1) com 2,4-D (1005 g e.a. ha-1) ou triclopyr (720 g e.a. ha-1), além da aplicação isolada dos respectivos graminicidas. Outro experimento contou com clethodim (54; 81; 108; 162; 216 g i.a