Weed Control and Turf Safety of Single and Sequential Applications of Herbicides Over Spring Seedings

Weed control is important during establishment of cool-season grasses, especially when seeded in spring near summer annual weed germination. Our objectives were to determine (i) turf safety and weed control from sequential applications of newly-released herbicides on tall fescue at three seeding dates (May, June, July) and (ii) turf safety and weed control from newly-released herbicides applied at seeding or shortly after emergence of spring-seeded Kentucky bluegrass or tall fescue. No herbicides tested negatively affected turfgrass establishment and usually improved turf establishment by reducing weed competition. Mesotrione consistently provided effective weed control and turf cover from either single or sequential applications over different locations, years, seeding dates, and turf species. Quinclorac or siduron applied as single or sequential applications or quinclorac+carfentrazone as a single application provided effective weed control and turf cover depending on seeding date and application regime. Although spring seeding can be achieved with high maintenance, it is strongly recommended to seed cool season grasses at the optimal time from late summer to early fall.