Herbicide Resistance Management Via Fraise Mowing

ABSTRACT Fraise mowing is a turfgrass cultivation practice used to mechanically control annual bluegrass via a combination of physical removal and seedbank depletion. Research was conducted to determine if fraise mowing could restore the efficacy of annual bluegrass control herbicides lost due to resistance. Herbicide treatments were applied to plots within separate fraise-mowed and non-fraise-mowed experiments conducted on a hybrid bermudagrass golf course fairway infested with annual bluegrass resistant to herbicides from Groups 2, 3, 5, and 29. Fraise mowing was performed on June 18, 2024 and June 23, 2025 to a 1.3 cm depth. Herbicide treatments included prodiamine, oxadiazon, indaziflam, simazine, metribuzin, pronamide, tetflupyrolimet, glyphosate, glufosinate, diquat dibromide, flumioxazin, foramsulfuron, and thiencarbazone + foramsulfuron + halosulfuron. Herbicides were applied according to label directions at preemergence (PRE), early-postemergence (EPOST), mid-postemergence (MPOST), or late postemergence (LPOST) timings during 2024-2026. In the fraise-mowed experiment, indaziflam, tetflupyrolimet, prodiamine, pronamide, simazine, and metribuzin controlled annual bluegrass 86 to 100% by 12 wk after initial treatment (WAIT) and 61 to 88% by 24 WAIT. Without fraise mowing, these herbicides resulted in ≤ 53% and ≤ 73% control 24 WAIT in 2024 and 2025, respectively. Increased efficacy may be related to a reduction in the annual bluegrass seedbank from fraise mowing as the practice reduced plant counts in non-treated check plots 75 to 88% each year. MPOST applications of diquat dibromide and flumioxazin controlled annual bluegrass 18 to 34% 6 WAIT in the fraise mowed experiment; whereas these same applications resulted in ≤ 10% control when applied to non-fraise mowed hybrid bermudagrass. MPOST applications of glyphosate and glufosinate and LPOST applications of foramsulfuron and thiencarbazone + foramsulfuron + halosulfuron performed similarly in both experiments. Restored use of residual herbicides lost due to resistance may remove barriers to adopting the practice of fraise mowing for annual bluegrass control.