Aminocyclopyrachlor (AMCP) is a pyrimidine carboxylic acid herbicide that is being evaluated for weed control on highway right-of-ways. The goal of this study was to evaluate weed control capabilities and tolerance of desirable turf to AMCP. The objective of the weed efficacy trial was to determine if AMCP (66, 132, and 263 g ai ha⁻¹) was as effective as aminopyralid (18, 53, and 88 g ai ha⁻¹) for controlling two weed species, mat lippia and Bidens alba. In 2011, AMCP applied at 132 g ai ha⁻¹ resulted in 93% control of mat lippia at 2 mo after treatment (MAT) and 65% control at 3 MAT. In 2012, AMCP at 66 or 132 g ha⁻¹ resulted in 93 to 97% control of mat lippia, respectively, at 3 MAT. Aminopyralid, applied POST, never exceed 10% control of mat lippia in 2011 and 60% control in 2012. AMCP, applied POST, at 66 g ha⁻¹, controlled of B. alba 84%, similar to the 89% control seen with aminopyralid at 88 g ha⁻¹. The level of control from AMCP of the two weed species was equal to or greater than aminopyralid. An additional objective was to determine the tolerance of common bermudagrass and ‘Pensacola' bahiagrass to AMCP (66, 132, and 263 g ai ha⁻¹) and imazapic (35 and 70 g ai ha⁻¹) applied alone and in combination. Applications were made in late spring during seedhead initiation. No additional chlorosis was detected when imazapic was applied in combination with AMCP for either turf species. Averaged across imazapic rates, AMCP at 66 and 132 g ha⁻¹, within the suggested rate range (48.5–132 g ai ha⁻¹), did not cause greater than 25% chlorosis at any time. Chlorosis observed for AMCP applied alone and in combination with imazapic was acceptable and decreased to zero by 8 to 10 wk after treatment.

Nomenclature: Aminocyclopyrachlor; aminopyralid; imazapic; ‘Pensacola' bahiagrass, Paspalum notatum FLUEGGE; common bermudagrass, Cynodon dactylon L. PERS.; mat lippia, Phyla nodiflora L. GREENE; Bidens alba L. DC.

Aminocyclopyrachlor (AMCP) es un herbicida pyrimidine carboxylic acid que está siendo evaluado para el control de malas hierbas en carreteras y caminos. El objetivo de este estudio fue evaluar la capacidad de control de malezas de AMCP y la tolerancia de céspedes deseables. El objetivo del ensayo de eficacia para el control de malezas fue determinar si AMCP (66, 132, y 263 kg ai ha⁻¹) fue tan efectivo como aminopyralid (18, 53, y 88 g ai ha⁻¹) para el control de dos especies de malezas, Phyla nodiflora y Bidens alba. En 2011, AMCP aplicado a 132 g ai ha⁻¹ resultó en 93% de control de P. nodiflora a 2 meses después del tratamiento (MAT) y 65% de control a 3 MAT. En 2012, AMCP a 66 ó 132 g ha⁻¹ resultó en 93 y 97% de control de P. nodiflora, respectivamente, a 3 MAT. Aminopyralid aplicado POST nunca superó 10% de control de P. nodiflora en 2011 y 60% de control en 2012. AMCP aplicado POST a 66 g ha⁻¹ controló B. alba 84%, lo cual fue similar al 89% de control observado con aminopyralid a 88 g ha⁻¹. El nivel de control con AMCP de las dos especies de malezas fue igual o mayor que con aminopyralid. Un objetivo adicional fue determinar la tolerancia del césped Cynodon dactylon y de Paspalum notatum 'Pensacola' a AMCP (66, 132, y 263 g ai ha⁻¹) e imazapic (35 y 70 g ai ha⁻¹) aplicados solos y combi