Studies were conducted in 2010 and 2011 to determine the effect of herbicide-based Palmer amaranth management systems in ‘Covington' sweetpotato. Treatments consisted of three herbicide application times. Pretransplant applications were flumioxazin at 107 g ai ha⁻¹, fomesafen at 280 g ai ha⁻¹, flumioxazin at 70 g ha⁻¹ plus pyroxasulfone at 89 g ai ha⁻¹, or no herbicide. A second herbicide application was applied within 1 d after transplanting (DAP) and consisted of S-metolachlor at 800 g ai ha⁻¹, clomazone at 630 g ai ha⁻¹, or no herbicide. Two weeks after planting (WAP) plots received S-metolachlor at 800 g ha⁻¹, metribuzin at 140 g ai ha⁻¹, a tank mix of S-metolachlor at 800 g ha⁻¹ plus metribuzin at 140 g ha⁻¹, hand-weeding followed by (fb) S-metolachlor at 800 g ha⁻¹, or no herbicide. Crop tolerance, Palmer amaranth control, and sweetpotato yield in systems containing fomesafen pretransplant were similar to flumioxazin-containing systems. Systems containing flumioxazin plus pyroxasulfone pretransplant resulted in increased crop stunting and decreased sweetpotato yield in 2010, compared with systems containing flumioxazin or fomesafen, but were similar to systems with flumioxazin or fomesafen in 2011. In 2010, systems containing S-metolachlor applied within 1 DAP resulted in increased sweetpotato injury, similar Palmer amaranth control, and reduced no. 1, jumbo, and total sweetpotato yield, compared with systems with clomazone. In 2011, systems containing clomazone were more injurious to sweetpotato than systems receiving S-metolachlor, but Palmer amaranth control and sweetpotato yield were similar. Systems containing metribuzin 2 WAP resulted in increased sweetpotato injury and Palmer amaranth control (in 2010) but similar no. 1 and total sweetpotato yields, compared with systems containing S-metolachlor at 2 WAP. Hand-weeding fb S-metolachlor provided greater Palmer amaranth control and no. 1 sweetpotato yield than did systems of S-metolachlor without a preceding hand-weeding event in 2010.

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

Se realizaron estudios en 2010 y 2011 para determinar los efectos de sistemas basados en herbicidas para el manejo de Amaranthus palmeri en batata 'Covington'. Los tratamientos consistieron en tres momentos de aplicación de herbicidas. Las aplicaciones pre-trasplante fueron flumioxazin a 107 g ai ha⁻¹, fomesafen a 280 g ai ha⁻¹, flumioxazin a 70 g ha⁻¹ más pyroxasulfone a 89 g ai ha⁻¹, o sin herbicida. Una segunda aplicación fue realizada 1 d después del trasplante (DAP) y consistió de S-metolachlor a 800 g ai ha⁻¹, clomazone a 630 g ai ha⁻¹, o sin herbicida. Dos semanas después de la siembra (WAP), las parcelas recibieron S-metolachlor a 800 g ha⁻¹, metribuzin a 140 g ai ha⁻¹, una mezcla en tanque de S-metolachlor a 800 g ha⁻¹ más metribuzin a 140 g ha⁻¹, deshierba manual seguida por (fb) S-metolachlor a 800 g ha⁻¹, o sin herbicida. La tolerancia del cultivo, el control de A. palmeri, y el rendimiento de la batata en sistemas que tuvieron fomesafen en pre-trasplante fueron similares a los sistemas con flumioxazin. Los sistemas que tuvieron flumioxazin más pyroxasulfone en pre-trasplante retrasaron el crecimiento del cultivo y disminuyeron el rendimiento de la batata en 2010, al compararse con si