Evaluation of Preemergence and Postemergence Herbicide Programs Used in Peanut(Arachis hypogaea) for Benghal Dayflower (Commelina benghalensis) Control

Benghal dayflower is a troublesome invasive weed in southeastern U.S. peanut production. Benghal dayflower is difficult to control due to extended emergence and limited herbicide options. Field trials were conducted in Jay, FL in 2022 and 2023 to evaluate the effectiveness of preemergence and postemergence herbicides labeled for use in peanut for Benghal dayflower control. The most effective preemergence treatments (≥90% control) at 28 days after treatment (DAT) were: Diclosulam plus dimethenamid-P (0.02 plus 0.63 kg ha⁻¹), diclosulam plus flumioxazin (0.02 plus 0.06 kg ha⁻¹), diclosulam plus S-metolachlor (0.02 plus 1.33 kg ha⁻¹), flumioxazin plus S-metolachlor (0.06 plus 1.33 kg ha⁻¹), and fluridone plus S-metolachlor (0.16 plus 1.33 kg ha⁻¹). These herbicide programs provided 78% to 90% density reduction and 67% to 71% biomass reduction at 56 DAT. By 56 DAT, no preemergence treatment provided >76% control, highlighting the need for timely postemergence application. Only preemergence herbicide programs containing S-metolachlor reduced Benghal dayflower density by >85% at 56 DAT. Among postemergence programs, paraquat plus bentazon plus S-metolachlor, paraquat plus bentazon plus premix carfentrazone-ethyl:pyroxasulfone, and paraquat plus S-metolachlor plus premix acifluorfen:bentazon provided >85% control from 14 to 56 DAT. While imazapic plus premix carfentrazone-ethyl:pyroxasulfone provided >80% control at 14 DAT, efficacy declined to <70% by 56 DAT. Overall, the results indicate that optimal Benghal dayflower control in peanut requires effective residual herbicide at planting followed by a timely postemergence application, preferably a paraquat-based program.