-Herbicides aminocyclopyrachlor and indaziflam are under development in Brazil. Information about the behaviors in Brazilian soils and climate is scarce. Thus, the present work has aimed to evaluate the persistence of biological activity and leaching potential of aminocyclopyrachlor and indaziflam in contrasting textured soils by means of bioassays. For the evaluation of persistence, four experiments were performed, in which soils with different textures were studied in different time periods between herbicide application and bioindicator sowing (beet and soybeans). To determine leaching potential, three blades of rainfall (0, 30 and 60 mm) were simulated, each constituting a single experiment in soils with different textures and five bands of depth in the columns. The bioindicator used for the leaching tests was beet. The persistence of biological activity of aminocyclopyrachlor and indaziflam was greater than 150 days. In clayey soil there was less persistent aminocyclopyrachlor than in the loam texture. For indaziflam there was no difference in persistence between the two soils. Regarding the leaching potential, it was observed that the precipitations have the capacity to interfere with the leaching of herbicides aminocyclopyrachlor and indaziflam. Aminocyclopyrachlor has greater potential for leaching than indaziflam. The first one has its mobility increased when applied to soil of loam texture in relation to very clayey soil. As for indaziflam, marked differences between soils with different textures have not been noticed.Keywords: residual activity, bioassay, organic matter. RESUMO -Os herbicidas aminocyclopyrachlor e indaziflam encontram-se em fase de desenvolvimento no Brasil. Informações a respeito do comportamento deles em condições edafoclimáticas brasileiras são escassas. O presente trabalho foi desenvolvido com o objetivo de avaliar a persistência da atividade biológica e o potencial de lixiviação do aminocyclopyrachlor e indaziflam em solos de texturas contrastantes, por meio de bioensaios. Para avaliação da persistência foram realizados quatro experimentos, em que foram estudados solos com texturas distintas em diferentes períodos de tempo entre a aplicação dos herbicidas e a semeadura do bioindicador (beterraba e soja
RESUMO -Com o objetivo de avaliar o efeito residual de flumioxazin sobre a emergência de plantas daninhas em solos de texturas distintas, foi realizado um experimento em casa de vegetação. Os tratamentos foram constituídos pela combinação de quatro épocas de aplicação: 14, 10, 7 e 0 dias antes da semeadura das espécies de plantas daninhas, com duas doses de flumioxazin (25 e 40 g ha ) e uma testemunha sem aplicação para cada planta daninha em solos de texturas distintas. O efeito residual do herbicida flumioxazin foi avaliado por meio da contagem do número de plantas emersas de cada espécie aos 35 dias depois da semeadura (DDS). O controle do fluxo inicial de emergência de plantas daninhas variou em função do tipo de solo, do período de tempo entre a aplicação e a semeadura das espécies e também da dose. A. tenella, D. horizontalis, D. insularis, D. tortuosum, E. heterophylla, N. physaloides e S. latifolia foram as espécies mais sensíveis à aplicação de flumioxazin (25 e 40 g ha).Palavras-chave: herbicida, atividade residual, controle de plantas daninhas.ABSTRACT -This work aimed to evaluate the residual effect of flumioxazin on weed emergence in soils of distinct textures. Treatments were constituted by the combination of four periods of application (14, 10, 7 and 0 days before sowing) with two rates of flumioxazin (25 and 40 g ha ), and no herbicide application for each weed species in soils with distinct textures. Residual activity of flumioxazin was evaluated by counting the emerged weeds for each species at 35 days after sowing. Control of initial flows of weed emergence varied with soil type, period of time between herbicide application and weed sowing. A. tenella, D. horizontalis, D. insularis, D. tortuosum, E. heterophylla, N. physaloides and S. latifolia, in both soils, were the most susceptible species to flumioxazin, applied at 25 and 40 g ha -1 .
Resumo-Portulaca oleracea é encontrada interferindo em diversas culturas principalmente em hortaliças, além de culturas como cana-de-açúcar e algodão. O trabalho foi desenvolvido com objetivo de aperfeiçoar a recomendação de alternativas de herbicidas utilizados em préemergência do algodoeiro, para o controle de P. oleracea. O trabalho foi realizado em duas etapas em casa-de-vegetação: a primeira para estabelecer, por meio da curva dose-resposta, as doses de herbicidas capazes de promover o controle eficiente de P. oleracea; a segunda, para verificar o período de atividade residual proporcionado pelas doses consideradas eficientes, selecionadas na primeira etapa e, por doses recomendadas. Na primeira etapa, foram utilizadas doses crescentes dos herbicidas alachlor, diuron, clomazone, oxyfluorfen, pendimethalin, prometryne, s-metolachlor, trifluralin 600 e trifluralin 450. Na segunda etapa, uma dose eficiente e uma dose recomendada de cada herbicida, foram aplicadas em quatro épocas antecedendo a semeadura da planta daninha, avaliando a porcentagem de controle aos 0, 10, 20 e 30 dias após aplicação dos tratamentos (DAA). Verificou-se na primeira etapa que os herbicidas controlaram eficientemente P. oleracea, com exceção das duas formulações de trifluralin. No entanto, as doses eficientes (C 95) de alachlor e prometryne apresentam curta atividade residual, como observado na segunda etapa. A dose recomendada de prometryne promoveu o controle eficiente até aos 30 DAA, ao contrário de alachlor. Diuron, pendimethalin, oxyfluorfen, s-metolachlor, em ambas as doses utilizadas, além da trifluralin 600 e clomazone, em doses recomendadas, apresentaram atividade residual eficiente por períodos de até 30 DAA, para o solo de textura franco argilo-arenosa.
Some species of Amaranthus are widely distributed in cotton crops. In recent years, ineffective weed control after herbicide use of some species has been reported. The current study was installed in order to find effective alternatives to a proper management of these species. Two simultaneous experiments were carried out for each species in this study (Amaranthus lividus and Amaranthus hybridus), and in each of them, a different stage of weed development (2 to 4 and 4 to 6 leaves) was focused. Twenty two herbicide combinations were arranged in a completely randomized design with four replicates for each experiment. Treatments were composed by the single or combined application of pyrithiobac-sodium, ammonium-glufosinate, glyphosate and trifloxysulfuron-sodium at different doses. For pyrithiobac, the best weed control results for both A. lividus and hybridus were found with applications of doses ≥ 28 g ha-1. Glufosinate and glyphosate presented excellent control of both Amaranthus species, despite doses or stages of application. Comparing the use of single herbicides and tank mixtures, trifloxysulfuron+pyrithiobac resulted in improved weed control only for early applications. No negative effects of Amaranthus species were observed for mixtures of glyphosate and pyrithiobac. Mixtures of pyrithiobac and glufosinate increased A. lividus and A. hybridus control levels.
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