As auxin-type herbicide-resistant crops become commercially available, nozzle selection will become a highly important variable for maintaining efficacy of herbicide solutions while minimizing off-target movement. Field experiments were conducted in 2013 and 2014 in Keiser, AR, to evaluate interactions among the N,N-bis-(aminopropyl)methylamine form of dicamba formulated as Engenia™, the potassium salt of glyphosate formulated as Roundup PowerMax®, and glufosinate formulated as Liberty® applied with three different nozzle types. Three TeeJet nozzles with an 11004 orifice (Turbo TeeJet [TT], Air Induction Extended Range [AIXR], and Turbo TeeJet Induction [TTI]) were used. To supplement the field data, droplet spectra for each nozzle and tank mixture combination were determined at the West Central Research and Extension Center in North Platte, NE. For most herbicide treatments and nozzle combinations, Palmer amaranth control 4 wk after treatment was > 95% both years. In 2013, TT nozzles provided 96% control of barnyardgrass and TTI nozzles provided 89% control, averaged across herbicides, except for Engenia alone. A similar effect of nozzle selection was observed in 2014. When treatments were applied to 20-cm-tall barnyardgrass in 2014, compared with 8-cm-tall plants in 2013, an antagonistic effect was observed when Engenia was tank-mixed with Roundup PowerMax. The weed control data correlated with the droplet spectrum analysis such that as volume median diameter (Dv50) increased from TT nozzles to the TTI nozzles, efficacy decreased for most tank mixtures. Results from the droplet analysis showed that Dv50 relative to water decreased for Liberty alone and not when tank-mixed with Engenia or Roundup PowerMax. These results suggest that nozzle selection will play a key role in maximizing efficacy of POST applications in dicamba-resistant crops. Additionally, evaluating droplet spectra of potential dicamba-containing tank mixtures is critical for producing desired droplet size to minimize off-target movement.
Nomenclature: Dicamba; glufosinate; glyphosate; barnyardgrass, Echinochloa crus-galli (L.) Beauv.; Palmer amaranth, Amaranthus palmeri S. Wats.
Al estar los cultivos resistentes a herbicidas de tipo auxinas comercialmente disponibles, la selección de la boquilla se convertirá en una variable altamente importante para mantener la eficacia de las soluciones de herbicidas y para minimizar el movimiento a lugares no deseados. Se realizaron experimentos de campo en 2013 y 2014 en Keiser, AR, para evaluar las interacciones entre la forma N,N-bis-(aminopropyl)metylamine de dicamba formulado como Engenia™, la sal de potassium de glyphosate formulado como Roundup PowerMax®, y glufosinate formulado como Liberty®, aplicados con tres tipos diferentes de boquillas. Se usaron tres boquillas TeeJet con un orificio 11004 (Turbo TeeJet [TT], Air Induction Extended Range [AIXR], y Turbo TeeJet Induction [TTI]). Para complementar los datos de campo, se determinó el espectro de gotas para cada combinación de boquilla y mezcla en tanque, en el Centro de Investigación y Extensión del Oeste Central, en North Platte, Nebraska. Para la mayoría de los tratamientos de combinaciones de herbicidas y boquillas, el control de Amaranthus palmeri, 4 semanas después del tratamiento, fue >95% en ambos años. En 2013, las boquillas TT brindaron 96% de control de Echinochloa crus-galli y las boquillas TTI brindaron 89% de control, al ser promediados los herbicidas, excepto por Engenia solo. Un efecto similar de la selección de boquilla fue observado en 2014. Cuando los tratamientos fueron aplicados a plantas de E. crus-galli de 20 cm de altura en 2014, en comparación con plantas de 8 cm de altura en 2013, se observó un ef
