Can Loyant-Coated Urea Mitigate Off-target Movement to Soybean?

Following the commercial launch of Loyant® (florpyrauxifen-benzyl) in 2018, occurrences of off-target movement of the herbicide were prevalent onto soybean [Glycine max (L.) Merr.] in proximity to rice (Oryza sativa L.). Field experiments were conducted in 2020 and 2021, in Fayetteville, Ark., to determine if Loyant-coated urea prills could mitigate damage to soybean from the herbicide in the instance of an off-target movement event in comparison to simulated spray drift. Seven low-dose rates of Loyant ranging from 0 to 3 fl oz/ac, were applied over the top of soybean at V3 as a foliar spray or coated urea and evaluated for visible injury at 7, 14, 21, and 28 days after treatment (DAT). In addition to visible injury, soybean yield was collected at harvest. A Weibull Growth curve (R2 = 0.99) was used to model visible injury at 21 DAT, and a Logistic 3P curve was fit for relative grain yield following harvest (R2 = 0.85), both as a function of herbicide rate. Additionally, a Logistic 3P model was used to regress the relationship between visible injury and relative soybean yield (R2 = 0.86). The predicted (a = 0.05) Loyant dose needed to elicit 80% visible injury to soybean from a coated or foliar application was 9.8 and 0.3 fl oz/ac, respectively, which was a 33-fold increase in soybean sensitivity when foliar spray drift occurs. At the maximum tested rate of Loyant (3 fl oz/ac), 100% of soybean yield was protected when the herbicide was coated on urea (54 bu./ac) in contrast to simulated spray drift (2 bu./ac). In areas where soybean is adjacent to rice, applications of Loyantcoated urea will likely mitigate injury to soybean as opposed to spray drift of the herbicide. [ABSTRACT FROM AUTHOR]