Field studies were conducted to evaluate POST herbicides with adjuvants for the control of three-cornered jack in winter wheat. The herbicides evaluated were fluroxypyr 9.7% w/w MCPA 38.8% w/w (formulated mixture [450 g ai ha⁻¹]), carfentrazone-ethyl (20 g ai ha⁻¹), bromoxynil 26.8% w/w MCPA 40.0% w/w (formulated mixture [450 g ai ha⁻¹]), thifensulfuron-methyl (75 g ai ha⁻¹), and tribenuron-methyl (75 g ai ha⁻¹), applied alone or tank mixed with the adjuvants alkyl ether sulfate sodium salt (625 mL ha⁻¹) or fatty alcohol ethoxylate (375 mL ha⁻¹). The addition of adjuvants to carfentrazone-ethyl resulted in > 94% control of three-cornered jack. Both adjuvants enhanced the efficacy of all herbicides for control of three-cornered jack, except thifensulfuron-methyl. However, a maximum increase in phytotoxicity on three-cornered jack was achieved with the addition of either adjuvant to tribenuron-methyl compared with herbicides used alone. Bromoxynil MCPA and carfentrazone-ethyl gave maximum wheat yield and yield components.

Nomenclature: Fluroxypyr MCPA; carfentrazone-ethyl; bromoxynil MCPA; thifensulfuron-methyl; tribenuron-methyl; three-cornered jack, Emex australis Steinheil; wheat, Triticum aestivum L.

Se realizaron estudios de campo para evaluar herbicidas POST con adyuvantes para el control de Emex australis en trigo de invierno. Los herbicidas evaluados fueron fluroxypyr 9.7% w/w MCPA 38.8% w/w (mezcla en formulación [450 g ai ha⁻¹]), carfentrazone-ethyl (20 g ai ha⁻¹), bromoxynil 26.8% w/w MCPA 40.0% w/w (mezcla en formulación [450 g ai ha⁻¹]), thifensulfuron-methyl (75 g ai ha⁻¹), y tribenuron-methyl (75 g ai ha⁻¹), aplicados solos o en mezcla en tanque con los adyuvantes sal de alkyl ether sulfate sodium (625 mL ha⁻¹) o alcohol graso ethoxylate (375 mL ha⁻¹). La adición de adyuvantes a carfentrazone-ethyl resultó en >94% de control de E. australis. Ambos adyuvantes mejoraron la eficacia de todos los herbicidas para el control de E. australis, excepto thifensulfuron-methyl. Sin embargo, un incremento máximo de fitotoxicidad en E. australis se alcanzó con la adición de cualquiera de los adyuvantes a tribenuron-methyl al compararse con los herbicidas usados solos. Bromoxynil MCPA y carfentrazone-ethyl brindaron el mayor rendimiento y componentes de rendimiento del trigo.