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Imazethapyr Co-Application Interactions in Imidazolinone-Resistant Rice

  • John Caleb Fish (a1), Eric P. Webster (a1), David C. Blouin (a2) and Jason A. Bond (a3)


A study was conducted to evaluate interactions of imazethapyr co-application with propanil, thiobencarb, or a prepackaged mixture of propanil plus thiobencarb. At 7, 14, 21, and 49 d after treatment (DAT), synergism occurred for red rice treated with imazethapyr at 70 g ai ha−1 mixed with propanil plus thiobencarb at 1,680 and 3,360 g ai ha−1. A synergistic response was also observed with imazethapyr at 70 g ha−1 mixed with propanil at 1,680 g ha−1; however, all other co-applications evaluated resulted in a neutral response with no antagonism observed. At 7 DAT, antagonism was observed for barnyardgrass when treated with imazethapyr at 70 g ha−1 mixed with propanil plus thiobencarb at 1,680 g ha−1, propanil at 840 g ha−1, or thiobencarb at 840 and 1,680 g ha−1; however, a synergistic response occurred for barnyardgrass control at 14, 21, and 49 DAT with imazethapyr at 70 g ha−1 mixed with propanil plus thiobencarb at 3,360 g ha−1. The synergistic response observed for red rice and barnyardgrass control with a mixture of imazethapyr plus propanil plus thiobencarb can benefit producers by increasing control of red rice and barnyardgrass, and this mixture contains three herbicides with three different modes of action, which can be part of an overall resistance-management strategy in imidazolinone-resistant (IR) rice.

Se realizó un estudio para evaluar las interacciones de imazethapyr co-aplicado con propanil, thiobencarb, o en mezclas pre-empacadas de propanil más thiobencarb. A 7, 14, 21, y 49 días después del tratamiento (DAT), ocurrió un sinergismo en arroz rojo tratado con imazethapyr a 70 g ai ha−1 mezclado con propanil más thiobencarb a 1,680 y 3,360 g ai ha−1. También se observó una respuesta sinérgica con imazethapyr a 70 g ha−1 mezclado con propanil a 1,680 g ha−1. Sin embargo, todas las demás co-aplicaciones evaluadas resultaron en una respuesta neutral sin observarse ningún antagonismo. A 7 DAT, se observó un antagonismo en Echinochloa crus-galli tratada con imazethapyr a 70 g ha−1 mezclado con propanil más thiobencarb a 1,680 g ha−1, propanil a 840 g ha−1, o thiobencarb a 840 y 1,680 g ha−1. Sin embargo, una respuesta sinérgica ocurrió en el control de E. crus-galli a 14, 21, y 49 DAT con imazethapyr a 70 g ha−1 mezclado con propanil más thiobencarb a 3,360 g ha−1. La respuesta sinérgica observada en el control de arroz rojo y de E. crus-galli con mezclas de imazethapyr más propanil más thiobencarb pueden beneficiar a los productores al incrementar el control de estas dos malezas. Además, estas mezclas contienen tres herbicidas con tres modos de acción diferentes, lo que puede ser parte de una estrategia general de manejo de resistencia en arroz resistente a imidazolinone (IR).


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