Chemical Interruption of Late Season Flowering to Improve Harvested Peanut Maturity

Peanut (Arachis hypogaea) is a botanically indeterminate plant where flowering, fruit initiation, and pod maturity occurs over an extended time period during the growing season. As a result, the maturity and size of individual peanut pods vary considerably at harvest. Immature kernels that meet commercial edible size specifications negatively affect quality during processing due to their increased propensity for off flavors, higher moisture and water activity, and variable roasting properties. As peanuts progress toward maturation, late season flowers set within 40 days till harvest will not have sufficient time to develop into mature, marketable pods prior to harvest. Research was conducted to determine the effect of late season flower termination on peanut yield, grade, and seed germination. Diflufenzopyr-Na (Diflufenzopyr) (BASF Biosciences), a synthetic auxin transport inhibitor, and the herbicide glyphosate were applied at three sub-lethal rates along with a ‘‘hand flower removal’’ and a nontreated control in both irrigated and non-irrigated plots. No differences in non-irrigated pod yield across all treatments were detected. Glyphosate at 56 and 112 g/ha increased non-irrigated sound mature kernels plus sound splits (SMKþSS) and decreased other kernels (OK). Non-irrigated seed germination was negatively affected by glyphosate. Diflufenzopyr at 17 and 25 g/ha increased irrigated peanut yield. Glyphosate at 112 and 168 g/ha increased irrigated SMKþSS and decreased OK and germination.