Field studies were conducted at Clinton, NC (2009, 2010), and Kinston, NC (2010), to determine ‘Covington' sweetpotato tolerance to flumioxazin applied after transplanting. Flumioxazin was directed to 25% of the sweetpotato vine beginning at the distal end (shoot tip), 25% of the vine beginning at the proximal end (crown), or to the entire vine (over-the-top) and was applied at 2 or 5 wk after transplanting (WAP). Applications made at 2 WAP resulted in 10 to 16% foliar necrosis at 3 WAP. Necrosis was transient and ≤ 2% by 6 WAP. Stunting injury at 6 WAP for flumioxazin applied at 2 WAP was greatest (12%) with the over-the-top application, followed by crown (5%), and shoot tip (1%) applications. Applications made at 5 WAP resulted in 35, 23, and 15% foliar necrosis at 6 WAP for over-the-top, crown, and shoot tip applications, respectively. By 12 WAP, stunting injury for all treatments was ≤ 3%. No. 1, jumbo, canner, and total marketable sweetpotato yield of the nontreated check was 36,670; 7,610; 7,170; and 51,450 kg ha⁻¹, respectively. No. 1 and total marketable sweetpotato yields were reduced when flumioxazin was applied at 2 or 5 WAP. No. 1 sweetpotato yield was reduced when flumioxazin was applied to the crown or over-the-top (27,240 and 28,330 kg ha⁻¹, respectively). Sweetpotato receiving flumioxazin applied to the shoot tip had similar no. 1 (31,770 kg ha⁻¹) yields as the nontreated check, crown, and over-the-top applications. Total marketable sweetpotato yield was reduced by flumioxazin application to shoot tip, crown, and over-the-top (45,350; 40,100; 40,370 kg ha⁻¹, respectively). Neither flumioxazin application timing nor placement influenced either jumbo- or canner-grade sweetpotato yields. Currently, after-transplant applications of flumioxazin do not appear to be a suitable fit for POST weed control in North Carolina sweetpotato production systems.

Nomenclature: Flumioxazin; sweetpotato; Ipomoea batatas (L.) Lam. ‘Covington'.

Se realizaron estudios de campo en Clinton, NC (2009, 2010) y Kinston, NC (2010) para determinar la tolerancia de la batata 'Covington' a aplicaciones de flumioxazin después del trasplante. La aplicación de flumioxazin fue dirigida al 25% de la enredadera de la batata empezando en la parte distal (punta del tallo), 25% de la enredadera empezando en la parte basal (corona), o en la enredadera entera (cobertura total), y se aplicó 2 y 5 semanas después del trasplante (WAP). Las aplicaciones hechas a 2 WAP resultaron en 10 a 16% de necrosis foliar 3 WAP. La necrosis fue transitoria y ≤2% a 6 WAP. El retraso en el crecimiento observado a 6 WAP debido a la aplicación de flumioxazin a 2 WAP fue mayor (12%) con la aplicación de cobertura total, seguida de la aplicación a la corona (5%) y a la punta del tallo (1%). Las aplicaciones hechas a 5 WAP resultaron en 35, 23, y 15% de necrosis foliar a 6 WAP para las aplicaciones de cobertura total, a la corona y a la punta del tallo, respectivamente. A 12 WAP, el retraso en el crecimiento fue ≤3% para todos los tratamientos. Los rendimientos de batata No. 1, jumbo, canner y total comercializable del testigo sin tratamiento fueron 36,670; 7,610; 7,170; y 51,450 kg ha⁻¹, respectivamente. El rendimiento de batata No. 1 y total comercializable se redujo cuando se aplicó flumioxazin a 2 ó 5 WAP. Los rendimientos de batata No. 1 se redujeron cuando se aplicó flumioxazin a la corona y en cobertura total (27,240 y 28,330 kg ha⁻¹, respectivamente). La batata que recibió flumioxazin en la punta del tallo tuvo rendimientos No. 1 (31,770 kg ha⁻¹) similares al testigo sin tratamiento, y las aplicaciones a la corona y de cobertura total. El rendimiento total comercializable de la batata se redujo debido a las aplicaciones de flumioxazin sobre la punta del tallo, la corona y de cobertur