Turf managers traditionally avoid seeding cool-season turfgrass in spring due to summer annual weed interference and poor growing conditions for cool-season grasses. Siduron is the most accepted herbicide for weed control in spring-seeded tall fescue, but it has low residual activity and does not control many weeds other than crabgrass. Isoxaflutole, mesotrione, and quinclorac were evaluated as alternatives to siduron. Single applications of these herbicides controlled crabgrass equivalent to or better than siduron. Sequential applications of isoxaflutole, mesotrione, or quinclorac effectively controlled smooth crabgrass without injuring tall fescue. Isoxaflutole and mesotrione controlled broadleaf plantain, henbit, and yellow woodsorrel; quinclorac marginally controlled henbit; and siduron did not control broadleaf weeds. Turfgrass cover 9 wk after seeding was dependent on environment and equivalent between treatments except at a location with predominately broadleaf weeds where siduron treatments resulted in less cover due to weed infestation. Sequential applications of isoxaflutole, mesotrione, and quinclorac provide an effective, safe option for chemical weed control during establishment of cool-season turfgrass.
Nomenclature: Isoxaflutole, mesotrione, quinclorac, siduron, broadleaf plantain, Plantago major L. #3 PLAMA, henbit, Lamium amplexicaule L. # LAMAM, smooth crabgrass, Digitaria ischaemum Schreb.ex Muhl. # DIGIS, yellow woodsorrel, Oxalis stricta L. # OXAST ‘Midnight’, tall fescue, Festuca arundinacea Schreb. ‘Crossfire II’.
Additional index words: Cool-season turfgrass, turfgrass establishment, turfgrass injury.
Abbreviations: EPOST, early postemergence; fb, followed by; GRF, Glade Road Research Facility, Blacksburg, VA; LPOST, late postemergence; TRC, Turfgrass Research Center, Blacksburg, VA; WAIT, weeks after initial treatment; WAP, weeks after planting.