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A Survey for Diclofop-Methyl Resistance in Italian Ryegrass from Tennessee and How To Manage Resistance in Wheat

  • Andrew T. Ellis (a1), Lawrence E. Steckel (a1), Christopher L. Main (a1), Marcel S. C. De Melo (a2), Dennis R. West (a1) and Thomas C. Mueller (a1)...


Italian ryegrass resistance to diclofop has been documented in several countries, including the United States. The purpose of this research was to screen selected putative resistant populations of Italian ryegrass for resistance to the acetyl-CoA carboxylase (ACCase)–inhibiting herbicides diclofop and pinoxaden and the acetolactate synthase (ALS)–inhibiting herbicides imazamox, pyroxsulam, and mesosulfuron in the greenhouse and to use field experiments to develop herbicide programs for Italian ryegrass control. Resistance to diclofop was confirmed in eight populations from Tennessee. These eight populations did not show cross-resistance to pinoxaden. One additional population (R1) from Union County, North Carolina, was found to be resistant to both diclofop and pinoxaden. The level of resistance to pinoxaden of the R1 population was 15 times that of the susceptible population. No resistance was confirmed to any of the ALS-inhibiting herbicides examined in this research. Field experiments demonstrated PRE Italian ryegrass control with chlorsulfuron (71 to 94%) and flufenacet + metribuzin (84 to 96%). Italian ryegrass control with pendimethalin applied PRE or delayed preemergence (DPRE) was variable (0 to 85%). POST control of Italian ryegrass was acceptable with pinoxaden, mesosulfuron, flufenacet + metribuzin, and chlorsulfuron + flucarbazone (> 80%). Application timing and herbicide treatment had no effect on wheat yield, except for diclofop and pendimethalin treatments, in which uncontrolled Italian ryegrass reduced wheat yield.

La resistencia de Lolium perenne L. ssp. multiflorum Lam. Husnot LOLMU al diclofop ha sido documentada en varios países incluyendo los EU. El propósito de este trabajo fue examinar la supuesta resistencia de poblaciones seleccionadas de Lolium perenne L. spp. multiflorum Lam. Husnot LOLMU a herbicidas inhibidores de AC Case diclofop y pinoxaden y a los herbicidas inhibidores ALS imazamox, pyroxsulam y mesosulfuron en el invernadero. También fue su objetivo, utilizar experimentos de campo para desarrollar programas de herbicidas en el control de Lolium perenne L. spp. multiflorum Lam. Husnot LOLMU. La resistencia al diclofop se confirmó en ocho poblaciones de Tennessee. Estas ocho poblaciones no mostraron resistencia cruzada a pinoxaden. Una población adicional del condado Unión de Carolina del Norte (R1) fue detectada como resistente a ambos diclofop y pinoxaden. El nivel de resistencia al pinoxaden de la población (R1) resultó ser 15 veces mayor que el de la población susceptible. No se confirmó resistencia a ninguno de los herbicidas inhibidores ALS examinados en esta investigación. Experimentos de campo mostraron control de Lolium perenne L. spp. multiflorum Lam. Husnot LOLMU en pre-emergencia (PRE) con chlorosulfuron (71 a 94%), y flufenacet + metribuzin (84 a 96%). El control de Lolium perenne L. spp. multiflorum Lam. Husnot LOLMU con pendimetalina PRE o Pre-emergencia tardía (DPRE) fue variable (0 a 85%). El control post-emergencia de Lolium perenne L. spp. multiflorum Lam. Husnot LOLMU alcanzó un nivel aceptable con pinoxaden, mesosulfuron, flufenacet + metribuzin, y chlorsulfuron + flucarbazone (> 80%). El tiempo de aplicación y el tipo de herbicida no tuvo efecto en el rendimiento del trigo, excepto en el caso de los tratamientos de diclofop y pendimetalina donde la falta de control de Lolium perenne L. spp. multiflorum Lam. Husnot LOLMU redujo el rendimiento del trigo.


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A Survey for Diclofop-Methyl Resistance in Italian Ryegrass from Tennessee and How To Manage Resistance in Wheat

  • Andrew T. Ellis (a1), Lawrence E. Steckel (a1), Christopher L. Main (a1), Marcel S. C. De Melo (a2), Dennis R. West (a1) and Thomas C. Mueller (a1)...


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