Glufosinate Application Timing and Rate Affect Peanut Yield

Abstract

ABSTRACT Field studies were conducted at 13 locations across the US peanut belt during 2010–2012 to evaluate peanut response to postemergence applications of glufosinate. Glufosinate was applied at 0, 41, 82, 164, 328 and 656 g ai/ha 30, 60, and 90 days after planting (DAP). There was a significant interaction for peanut yield between application time and glufosinate rate; peanut yield data were regressed on rate of glufosinate and fit to a log-logistic dose response curve by application timing. At 30 DAP, peanut yield ranged from 16 to 92% of the non-treated control, with glufosinate at 266 g/ha causing an estimated 50% reduction in yield (Y50). At 60 DAP, peanut yield ranged from 16 to 82% of the nontreated control, with Y50 = 266 g/ha of glufosinate. Peanut yield when glufosinate was applied at 90 DAP ranged from 20 to 78% of the non-treated control; Y50 = 187 g/ha of glufosinate, which was lower than that at 30 DAP and indicated greater peanut sensitivity. Peanut plants treated at 30 DAP had more time to recover from glufosinate injury at the lower rates and/or were in a less susceptible stage of growth relative to 90 DAP. These data provide peanut growers across the US with an estimate of potential yield losses associated with mis-application, off-target movement, or sprayer contamination of glufosinate.