RESUMO

Herbicides play an important role in preventing crop yield losses due to both their weed interference ability and their capacity for increasing soil conservation in no-till systems. Group A herbicides or acetyl-CoA carboxylase (ACCase) are essential tools the selective management of glyphosate resistance in grass weed species. In this review, we describe important aspects of ACCase biology and herbicides targeting this enzyme, along with a discussion on stewardship programs to delay the evolution of herbicide resistance which can evolve either through target site and/or non-target site mechanisms. Sixteen-point mutations have been reported to confer resistance to ACCase inhibitors. Each mutation confers cross resistance to a different group of herbicides. Metabolic resistance can result in resistance to multiple herbicides with different mechanisms of action (MoA), and herbicide detoxification is often conferred by cytochrome P450 monooxigenases and glutathione- S -transferases. Regardless of whether resistance mechanisms are target or non-target site, using herbicides with the same MoA will result in resistance evolution. Therefore, while field surveys and resistance mechanism studies are crucial for designing reactive management strategies, integrated weed management plays a central role in both reactive and proactive mitigation of herbicide resistance evolution.

Assuntos

RESUMO

Herbicides play an important role in preventing crop yield losses due to both their weed interference ability and their capacity for increasing soil conservation in no-till systems. Group A herbicides or acetyl-CoA carboxylase (ACCase) are essential tools the selective management of glyphosate resistance in grass weed species. In this review, we describe important aspects of ACCase biology and herbicides targeting this enzyme, along with a discussion on stewardship programs to delay the evolution of herbicide resistance which can evolve either through target site and/or non-target site mechanisms. Sixteen-point mutations have been reported to confer resistance to ACCase inhibitors. Each mutation confers cross resistance to a different group of herbicides. Metabolic resistance can result in resistance to multiple herbicides with different mechanisms of action (MoA), and herbicide detoxification is often conferred by cytochrome P450 monooxigenases and glutathione- S -transferases. Regardless of whether resistance mechanisms are target or non-target site, using herbicides with the same MoA will result in resistance evolution. Therefore, while field surveys and resistance mechanism studies are crucial for designing reactive management strategies, integrated weed management plays a central role in both reactive and proactive mitigation of herbicide resistance evolution.(AU)

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RESUMO

Com o advento do cultivo de algodão em segunda safra, o controle de plantas voluntárias de soja RR® tornou-se uma operação indispensável na cotonicultura. Assim, o presente trabalho teve por objetivo avaliar a eficiência de diferentes alternativas de controle químico de plantas voluntárias de soja RR®, mediante a avaliação de herbicidas empregados no algodão. Foram instalados dois experimentos em casa de vegetação, sendo um com plantas de soja em estádio V1 e o outro em V2. Foram avaliados 21 tratamentos, sendo que estes compostos pela aplicação isolada e em mistura dos herbicidas pyrithiobac-sodium, amonio-glufosinate, glyphosate e trifloxysulfuron-sodium em diferentes doses. As variáveis analisadas foram: controle aos 7 e 28 dias após a aplicação dos herbicidas (DAA); matéria seca e altura das plantas aos 28 DAA. Os resultados demonstraram que nenhuma das misturas entre os herbicidas apresentaram antagonismo no controle de soja RR®. Diferentes níveis de supressão podem ser obtidos pela aplicação dos herbicidas avaliados, porém, apenas o amonio-glufosinate isolado ou associado ao pyrithiobac-sodium controlou todas as plantas voluntárias, independentemente do estádio de aplicação. Em geral, a soja apresentou maior tolerância aos herbicidas testados quando em estádio de crescimento mais avançado.

With the advent of cotton cultivation in the second harvest, the control of volunteer soybean GR® has become an indispensable operation on cotton. So, this study had to evaluate the efficiency of different alternatives to chemical control of volunteer plants RR® soybean, through an assessment of herbicides used in cotton. Two experiments were established in greenhouse, one with soybean plants in stage V1 and the other in V2. There were evaluated 21 treatments, compounds by alone and in mixture of herbicides pyrithiobac-sodium, amonio-glufosinate, glyphosate and trifloxysulfuron-sodium at different rates. The variables analyzed were: control at 7 and 28 days after herbicide application (DAA), dry weight and plant height at 28 DAA. The results showed that none of the mixtures showed antagonism between the herbicides in control of GR® soybeans. Different levels of suppression can be obtained by application of the herbicides evaluated, but, only the amonio-glufosinate, isolated and associated with pyrithiobac-sodium controlled all volunteer plants, regardless of the application stage. In general, soybean was more tolerant to herbicides while in more advanced growth stage.

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