An Evaluation of Pre-emergence Metam-Potassium and S-metolachlor for Yellow Nutsedge (Cyperus esculentus) Management in Sweetpotato. (8th May 2017) - Meyers, Stephen L.
Abstract : Field studies were conducted in 2014 and 2015 at Pontotoc, MS to evaluate combinations of metam-potassium and S -metolachlor for yellow nutsedge control and sweetpotato crop response. Treatments consisted of a factorial of five metam-potassium rates (0, 149, 261, 372, and 484 kgha −1 ) by three S -metolachlor rates (0, 0.80, and 1.34 kgha −1 ). Additionally, a hand-weeded check was included for comparison. Crop injury was limited to ≤4% at 4 weeks after transplanting (WAP) and was transient. At 2 WAP yellow nutsedge control was 58, 74, and 76% in plots treated with S -metolachlor at 0, 0.80, and 1.34 kgha −1, respectively. Nutsedge control in all treatments decreased from 2 to 15 WAP. At 15 WAP, S -metolachlor at 0, 0.80, and 1.34 kg ha −1 provided 35, 68, and 70% yellow nutsedge control, respectively. Metam-potassium rate did not influence yellow nutsedge control after transplanting. Sweetpotato yields in the hand-weeded check were 4, 640; 22, 180; 7, 180; 34, 000; and 1, 360 kgha −1 for jumbo, no. 1, canner, marketable, and cull grades, respectively. S -metolachlor applied at either 0.80 or 1.34 kgha −1 provided jumbo, no. 1, and marketable sweetpotato yields equivalent to the hand-weeded check. Canner and cull yields were not influenced by S -metolachlor rate. Metam-potassium rates used in the present study resulted in yields equal to or greater than the hand-weeded check.