Postemergence Yellow Nutsedge Management in Sweetpotato

Abstract

Field studies were conducted in 2013 at Houlka, MS and in 2014 at Houston, MS to evaluate herbicide programs for yellow nutsedge control and sweetpotato crop response. Treatments consisted of halosulfuron-methyl at 13, 26, and 34 g ai ha−1 2 wk after transplanting (WAP) followed by (fb) S-metolachlor at 856 g ai ha−1 4 WAP; a sequential application of 13 g ha−1 halosulfuron-methyl at 2 and 4 WAP; and halosulfuron-methyl at 13 g ha−1 plus either S-metolachlor or 1,123 g ai ha−1 alachlor 2 WAP. Crop injury in treated plots ranged from 29 to 44% at 3 WAP. Injury from the sequential application increased slightly between 3 and 5 WAP (29 to 38%), but decreased between 5 WAP and harvest (19%). Injury with all other treatments was unchanged from 5 WAP through harvest. The sequential application of halosulfuron-methyl provided the greatest control of yellow nutsedge throughout the duration of the study with ≥ 83% control from 5 WAP through harvest. Control from all other treatments ranged from 38 to 78% from 5 WAP through harvest. No. 1, canner, and marketable sweetpotato yields of the hand-weeded check were 19,900; 7,140; and 27,590 kg ha−1, respectively. No. 1, canner, and marketable yields of the weedy check were only 15, 51, and 25% of the hand-weeded check, respectively. With the exception of halosulfuron-methyl at 13 g ha−1 fb S-metolachlor, which was similar to the weedy check, no. 1 and marketable yields with all treatments were greater than the weedy check, but less than the weed-free check. A sequential application of halosulfuron-methyl and a tank mix of halosulfuron-methyl plus S-metolachlor would fit well into an overall yellow nutsedge management program in sweetpotato. However, as halosulfuron-methyl is not registered for use in sweetpotato, growers must continue to manage yellow nutsedge primarily with crop rotation and sanitation.