Turf safety and effectiveness of dithiopyr and quinclorac for large crabgrass (Digitaria sanguinakis) control in spring-seeded turf

There are Limited options for controlling large crabgrass in spring-seeded cool-season turf. The objective of this experiment was to evaluate the safe ty and effectiveness of dithiopyr and quinclorac to control large crabgrass in spring-seeded Kentucky bluegrass and perennial ryegrass stands. Quinclo rac at 0.84 kg/ha and dithiopyr at 0.56 kg/ha were applied separately at va rious times prior to seeding and after emergence of Kentucky bluegrass and perennial ryegrass. Quinclorac applied once at 2, 4, 8, or 12 weeks after e mergence (WAE) or split-applied preplant incorporated (PPI) + 12 WAE will g ive season-long control of large crabgrass with no injury to spring-seeded Kentucky bluegrass or perennial ryegrass, Quinclorac applied PPI or 0 WAE i s safe to use in spring seedings, but it will not provide season-long contr ol of large crabgrass. Dithiopyr applied 2 or 4 WAE will control large crab grass season-long while not injuring spring-seeded Kentucky bluegrass or pe rennial ryegrass. However, dithiopyr applied PPI or 0 WAE will severely lim it germination of desirable turf, and dithiopyr applied 8 or 12 WAE will no t control mature crabgrass.