Successful weed control before seeding is necessary for proper turfgrass establishment. However, herbicide labels differ in the time required between application and seeding. The objective of this research was to determine the influence of four postemergence broadleaf combination herbicides on tall fescue (Festuca arundinacea) cover, normalized difference vegetation index (NDVI), and canopy height when seeded 0, 3, 7, and 14 days after herbicide application. Herbicide treatments included the following: 1) a nontreated control; 2) 0.03 lb/acre carfentrazone-ethyl + 0.09 lb/acre methylchlorophenoxypropionic acid (MCPP) + 1.44 lb/acre 2,4-dichlorophenoxyacetic acid (2,4-D) + 0.30 lb/acre dicamba; 3) 0.20 lb/acre fluroxypyr + 0.01 lb/acre halauxifen-methyl + 1.44 lb/acre 2,4-D choline; 4) 0.20 lb/acre triclopyr + 0.003 lb/acre pyraflufen-ethyl + 1.72 lb/acre 2,4-D + 0.14/acre dicamba; and 5) 0.04 lb/acre penoxsulam + 0.04 lb/acre sulfentrazone + 0.40 lb/acre 2,4-D + 0.11 lb/acre dicamba. Penoxsulam + sulfentrazone + 2,4-D + dicamba reduced tall fescue cover, NDVI, and canopy height compared with the nontreated. This research demonstrates seeding between 0 to 14 days after an application of carfentrazone-ethyl + MCPP + 2,4-D + dicamba, fluroxypyr + halauxifen-methyl + 2,4-D choline, or triclopyr + pyraflufen-ethyl + 2,4-D + dicamba will result in successful tall fescue establishment under the conditions evaluated in these experiments.
The objective of this greenhouse study was to evaluate tall fescue (Festuca arundinacea) seedling growth when seeded after herbicide application. Herbicide treatments included a nontreated control; 1.19 lb/acre 2,4-dichlorophenoxyacetic acid (2,4-D) + 0.32 lb/acre methylchlorophenoxypropionic acid (MCPP) + 0.32 lb/acre dicamba; 0.75 lb/acre quinclorac; and 0.06 lb/acre halosulfuron-methyl. Seeding was done at 0, 3, 7, or 14 days after herbicide application to soil media. Two identical experiments were conducted in the greenhouse: Expt. 1 seedling growth from January to March and Expt. 2 from May to July (temperatures higher). Seeding dates after herbicide application did not influence growth. Average dry shoot weight reductions and dry root weight reductions caused by postemergence herbicides were 2,4-D + MCPP + dicamba (33% shoot and 27% root in Expt. 2), quinclorac (30% shoot and 37% root in Expt. 2), and halosulfuron-methyl (51% shoot in Expt. 2; 81% root in Expts. 1 and 2). Although application of these herbicides before seeding in the field may result in no visual impact, they can impact seedling shoot and root growth, particularly under higher growth temperatures.