Tolerance of Sweetpotato to Herbicides Applied in Plant Propagation Beds

Field and greenhouse studies were conducted in 2016 and 2017 to determine sweetpotato tolerance to herbicides applied to plant propagation beds. Herbicide treatments included PRE application of flumioxazin (107 g ai ha−1),S-metolachlor (800 g ai ha−1), fomesafen (280 g ai ha−1), flumioxazin plusS-metolachlor (107 g ai ha−1+ 800 g ai ha−1), fomesafen plusS-metolachlor (280 g ai ha−1+ 800 g ai ha−1), fluridone (1,120 or 2,240 g ai ha−1), fluridone plusS-metolachlor (1,120 g ai ha−1+ 800 g ai ha−1), napropamide (1,120 g ai ha−1), clomazone (420 g ai ha−1), linuron (560 g ai ha−1), linuron plusS-metolachlor (560 g ai ha−1+ 800 g ai ha−1), bicyclopyrone (38 or 49.7 g ai ha−1), pyroxasulfone (149 g ai ha−1), pre-mix of flumioxazin plus pyroxasulfone (81.8 g ai ha−1+ 104.2 g ai ha−1), or metribuzin (294 g ai ha−1). Paraquat plus non-ionic surfactant (280 g ai ha−1+ 0.25% v/v) POST was also included. After plants in the propagation bed were cut and sweetpotato slip number, length, and weight had been determined, the slips were then transplanted to containers and placed either in the greenhouse or on an outdoor pad to determine any effects from the herbicide treatments on initial sweetpotato growth. Sweetpotato slip number, length, and/or weight were affected by flumioxazin with or withoutS-metolachlor,S-metolachlor with or without fomesafen, clomazone, and all fluridone treatments. In the greenhouse studies, initial root growth of plants after transplanting was inhibited by fluridone (1,120 g ai ha−1) and fluridone plusS-metolachlor. However, by 5 wk after transplanting few differences were observed between treatments. Fomesafen, linuron with or withoutS-metolachlor, bicyclopyrone (38 or 49.7 g ai ha−1), pyroxasulfone with or without flumioxazin, metribuzin, and paraquat did not cause injury to sweetpotato slips in any of the studies conducted.