Selectivity of glyphosate tank mixtures for RR soybean Seletividade de glyphosate em misturas em tanque para soja RR

• Published in: Planta daninha 2011-12, Vol.29 (4), p.929-937
• Main Authors: D.G Alonso, J Constantin, R.S Oliveira Jr, J.G.Z Arantes, S.D Cavalieri, G Santos, F.A Rios, L.H.M Franchini
• Format: Article
• Language: English
• Subjects: glyphosate-resistant soybean; herbicidas; herbicides; injuria; injury; soja resistente ao glyphosate; tolerance; tolerância
• ISSN: 0100-8358
• DOI: 10.1590/S0100-83582011000400024

An active ingredients mixture of different action mechanisms is an essential tool to prevent or manage areas with resistant weeds. However, it is important that such a mixture provides adequate selectivity to the crop. The aim of this work was to evaluate glyphosate selectivity to glyphosate-resistant (RR) soybean, and also verify if there is selectivity in mixtures with other active ingredients applied postemergence aimed at new control strategies, which might be used in RR soybean cultivation. The herbicides and respective rates (g ha-1) evaluated were: glyphosate (720, 960, 1,200, and 1,440), and the mixtures of glyphosate (960) with cloransulam-methyl (30.24), fomesafen (125), lactofen (72), chlorimuron-ethyl (12.5), flumiclorac-pentyl (30), bentazon (480), or imazethapyr (80). All treatments were applied in postemergence when the soybean crop was at V2 to V3 stage. Treatments with glyphosate or in mixtures with postemergent herbicides showed visual effects of phytotoxicity when applied to the glyphosate-resistant soybean. Effects such as reduction in plant height, crop closure, number of pods per plant, and hundred grain weight could be observed. However, the effects related to plant development were mostly transient and did not persist during the crop cycle. Among the studied treatments, only the mixture of glyphosate and lactofen was not selective to the crop, promoting negative effects on most characteristics analyzed and consequently reducing grain yield.A mistura de ingredientes ativos de diferentes mecanismos de ação é uma ferramenta essencial para prevenir ou manejar áreas com plantas daninhas resistentes. No entanto é importante que tais associações forneçam adequada seletividade para a cultura. O objetivo deste trabalho foi avaliar a seletividade do glyphosate a soja RR, e verificar também, se existe seletividade a misturas com outros ingredientes ativos, aplicados em pós-emergência, visando novas estratégias de controle que poderão ser empregadas no cultivo da soja RR. Os herbicidas e respectivas doses (g ha-1) avaliadas foram: glyphosate isolado (720, 960, 1.200 e 1.440) e as misturas de glyphosate (960) com cloransulam-methyl (30,24), fomesafen (125), lactofen (72), chlorimuron-ethyl (12,5), flumiclorac-pentyl (30), bentazon (480) e imazethapyr (80). Todos os tratamentos foram aplicados em dose única em pós-emergência quando a soja estava no estádio V2 a V3. Tratamentos com glyphosate isolado ou em mistura com herbicidas pós-emergentes apl