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Field studies at six locations over 3 yr in Kansas compared pyroxsulam at two application timings to competitive standards for winter annual weed control in winter wheat. Pyroxsulam applied fall-POST (FP) controlled downy brome 84 to 99% and was similar to or greater than sulfosulfuron, propoxycarbazone, or propoxycarbazone plus mesosulfuron. Downy brome control was lower when application timing was delayed until spring (SP), such that no herbicide provided more than 90% downy brome control. Cheat control was 97% or more with almost all herbicides applied FP, and greater than 90% in most locations when herbicides were applied SP. Sulfosulfuron was the exception with only 30 to 81% cheat control. All FP-applied herbicides, except sulfosulfuron at Manhattan, KS, controlled blue mustard 95% or more. Pyroxsulam and propoxycarbazone plus mesosulfuron FP completely controlled henbit at Hesston, KS, in 2009, but no herbicide treatment provided more than 60% control when applied SP. Averaged over application timings, pyroxsulam provided the greatest henbit control (76 and 78%) at Manhattan and Hays, respectively, in 2009, and FP treatments were 33 and 28 percentage points more effective than SP treatments at those locations. Averaged over application timing, wheat yields did not differ between herbicide treatments in five of six locations. Averaged over herbicide treatment, FP-treated wheat yielded more grain than SP-treated wheat at three of the six locations.
Nomenclature: Mesosulfuron; propoxycarbazone; pyroxsulam; sulfosulfuron; blue mustard, Chorispora tenella (Pallas) DC. COBTE; cheat, Bromus secalinus L. BROSE; downy brome, Bromus tectorum L. BROTE; henbit, Lamium amplexicaule L. LAMAM; common wheat, Triticum aestivum L.
Key words: DE-742, GF-1274, herbicide, treatment stage.
En seis localidades de Kansas, se realizaron estudios de campo durante tres años comparando pyroxsulam en dos diferentes tiempos de aplicación en estándares competitivos para el control de maleza anual de invierno, en cultivo de trigo invernal (Triticum aestivum). El pyroxsulam aplicado en post emergencia en otoño (FP) controlóBromus tectorum 84 a 99% y obtuvo resultados similares o mayores que sulfosulfurón, propoxycarbazone o propoxycarbazone más mesosulfurón. El control de B. tectorum fue menor cuando las etapas de aplicación se retrasaron hasta la primavera (SP), de tal manera, que ningún herbicida proporcionómás de 90% de control de esta maleza. El control de B. secalinus fue de 97% o más con todos los herbicidas...