Evaluation of Tenacity Selected Fine Fescues to Eleven Rates of Tenacity from 0-8966 Grams a.I. ha-1.

The fine fescues (Festuca spp.) are a group of cool-season grasses that are better adapted to cool, dry, shaded environments, infertile, acidic soils and drought conditions. They also exhibit the best performance under lower fertility levels than other cool-season turfgrasses. These qualities give them the reputation of being low maintenance grasses. Tenacity is an HPPD inhibiting herbicide that has good pre- and post-emergent control of many problematic grassy weeds including Poa annua.  Currently the Tenacity label does not recommend use in fine fescues at seeding.  The Rutgers Breeding program has been working to breed Tenacity tolerant fine fescues where the herbicide can be utilized safely.  This research is an evaluation of three lines of hard fescue, three lines of Chewings fescue and three lines of strong creeping red fescue from the Tenacity selected breeding material and were selected based on their injury from a field application of Tenacity.  Plants were established from vegetative plugs in conetainers and kept in a growth chamber maintained at 25/15 ℃ day/night temperature and 50% humidity and ten hour photoperiod.  Herbicide treatments were applied in a spray chamber set to deliver 280 L ha^-1 at rates of 0, 17.5, 35, 70, 140, 280, 560, 1121, 2242, 4483, and 8966 grams a.i. ha^-1  + 0.25% non ionic surfactant.  Visual percent injury ratings were taken and means separated using fishers protected LSD.  Hard fescues were the most tolerant species and strong creeping red fescue the least tolerant species overall.