Studies were conducted in 2012 and 2013 to determine the effect of fomesafen based Palmer amaranth control program in ‘Covington' and ‘Evangeline' sweetpotato cultivars. Treatments consisted of fomesafen pretransplant alone at 0.20, 0.28, 0.36, 0.42, 0.56, and 0.84 kg ai ha⁻¹ or followed by (fb) S-metolachlor at 1.12 kg ai ha⁻¹ 0 to 7 d after transplanting (DAP), fomesafen at 0.28 kg ha⁻¹ fb S-metolachlor at 1.12 kg ha⁻¹14 DAP, flumioxazin pretransplant at 0.105 kg ai ha⁻¹, S-metolachlor at 1.12 kg ha⁻¹ 0 to 7 DAP, clomazone at 0.63 kg ha⁻¹ 0 to 7 DAP, napropamide at 2.24 kg ha⁻¹ 0 to7 DAP, flumioxazin fb S-metolachlor 0 to 7 DAP, and flumioxazin fb clomazone fb S-metolachlor 14 DAP. Fomesafen pretransplant at 0.28 to 0.84 kg ha⁻¹ alone or followed by S-metolachlor at 1.12 kg ha⁻¹ 0 to 7 DAP provided 80 to 100% Palmer amaranth control without reduction of yield and significant (< 13%) injury in Covington and Evangeline sweetpotato. Flumioxazin alone or fb S-metolachlor and flumioxazin fb clomazone fb S-metolachlor provided Palmer amaranth control (≥ 95%) with little injury (≤ 5%) and similar yield to the weed-free check. Clomazone alone did not cause injury, but controlled only 24 to 32% of Palmer amaranth at 50 DAP, which resulted in reduced no. 1, marketable, and total sweetpotato yield. Napropamide provided inconsistent control of Palmer amaranth in both years; therefore jumbo and total sweetpotato yield was reduced as compared to the weed-free check in 2012. Palmer amaranth control, sweetpotato cultivar tolerance, and yield in treatments with fomesafen fb S-metolachlor were similar to flumioxazin fb S-metolachlor. In conclusion, a herbicide program consisting of pretransplant fomesafen (0.28 to 0.42 kg ha⁻¹) fb S-metolachlor (1.12 kg ha⁻¹) is a potential option to control Palmer amaranth without causing significant injury and yield reduction in sweetpotato.

Nomenclature: Clomazone; flumioxazin; fomesafen; S-metolachlor; napropamide; Palmer amaranth, Amaranthus palmeri S. Wats.; sweetpotato, Ipomoea batatas (L.) Lam. ‘Covington', ‘Evangeline'.

En 2012 y 2013, se realizaron estudios para determinar el efecto de programas de control de Amaranthus palmeri basados en el uso de fomesafen sobre los cultivares de batata ‘Covington’ y ‘Evangeline’. Los tratamientos consistieron de fomesafen solo en pre-trasplante a 0.20, 0.28, 0.36, 0.42, 0.56, y 0.84 kg ai ha⁻¹ o seguido por (fb) S-metolachlor a 1.12 kg ai ha⁻¹ 0 a 7 d después del trasplante (DAP), fomesafen a 0.28 kg ha⁻¹ fb S-metolachlor a 1.12 kg ha⁻¹ 14 DAP, flumioxazin en pre-trasplante a 0.105 kg ai ha⁻¹, S-metolachlor a 1.12 kg ha⁻¹ 0 a 7 DAP, clomazone a 0.63 kg ha⁻¹ 0 a 7 DAP, napropamide a 2.24 kg ha⁻¹ 0 a 7 DAP, flumioxazin fb S-metolachlor 0 a 7 DAP, y flumioxazin fb clomazone fb S-metolachlor 14 DAP. Fomesafen solo en pre-trasplante de 0.28 a 0.84 kg ha⁻¹ o seguido por S-metolachlor a 1.12 kg ha⁻¹ 0 a 7 DAP brindó 80 a 100% de control de A. palmeri sin reducir el rendimiento ni causar daño significativo (<13%) en batata Covington y Evangeline. Flumioxazin solo o fb S-metolachlor y flumioxazin fb clomazone fb S-metolachlor controlaron A. palmeri (≥95%), causaron poco daño (≤5%), y el rendimiento fue similar al testigo libre de malezas. Clomazone solo no causó daño, pero el control de