Peanut Response to Carfentrazone-ethyl and Pyraflufen-ethyl Applied Postemergence1

Abstract

Abstract Field experiments were conducted at six locations in Texas in 2004 and 2005 to evaluate peanut tolerance to carfentrazone-ethyl and pyraflufen-ethyl. Carfentrazone-ethyl at 27 and 36 g ai/ha or pyraflufen-ethyl at 2.6 and 3.5 g ai/ha were applied early postemergence (EP) 28 to 51 days after planting (DAP) or late postemergence (LP) 93 to 121 DAP in weed-free plots. In the Texas High Plains, carfentrazone-ethyl and pyraflufen-ethyl applied EP resulted in 62 and 48% visual injury, respectively, when rated 14 days after treatment (DAT). With the exception of the low rate of carfentrazone-ethyl at one location, this injury was greater than the injury caused by paraquat at 210 g ai/ha plus bentazon at 280 g ai/ha. All injury declined over time, but was still apparent at harvest (up to 3%). Peanut injury from applications made late postemergence did not exceed 16%. In the Rolling Plains, peanut injury did not exceed 12% at Lockett and 25% at Rochester regardless of herbicide, rate, or timing. In south Texas, peanut injury ranged from 14 to 19% and 6 to 8% following EP and LP applications, respectively. At this location, carfentrazone-ethyl and pyraflufen-ethyl at the low rate caused less injury than paraquat plus bentazon when applied EP. Peanut yield was reduced by herbicide treatment at two of six locations. Greatest yield losses were observed at Lamesa in 2004, where all carfentrazone-ethyl treatments, except the lowest rate applied LP, and all pyraflufen-ethyl treatments caused a yield reduction when compared to the non-treated control. No reduction in grade from the non-treated control was observed at the five locations where grade analysis was performed.