218-4 ALS Resistant Annual Sedge Confirmed in Georgia.
See more from this Division: C05 Turfgrass Science
See more from this Session: Turfgrass Science: I
Abstract:
Abstract. Acetolactate synthase (ALS) inhibitors are widely used for POST control of sedges (Cyperus spp.) in turfgrass. A suspected resistant (R)-biotype of annual sedge was collected from a bermudagrass turf in Georgia with a history of exclusive use of halosulfuron-methyl. The objectives of this research were to evaluate (1) the resistance levels to halosulfuron-methyl, (2) efficacy of various herbicides for control, and (3) the molecular and physiological basis for resistance. In greenhouse experiments, the halosulfuron-methyl rate required to reduce shoot biomass 50% from the nontreated at 8 weeks after treatment (WAT) measured 8 and >1120 g ai ha-1 for the S and R-biotype, respectively. Imazapic, sulfosulfuron, and trifloxysulfuron-sodium reduced biomass of the S-biotype >60% at 8 WAT, but biomass was reduced ≤20% for the R-biotype. Glufosinate, glyphosate, MSMA, and sulfentrazone reduced shoot biomass of the R-biotype by 93, 86, 97, and 45%. In laboratory experiments, the halosulfuron-methyl concentration required to inhibit isolated ALS enzymes 50% measured 58 and >1000 mM for the S and R-biotypes, respectively. Gene sequencing of the R-biotype revealed a Pro-197-Ser substitution that confers resistance to ALS-inhibitors. This is the first report of ALS-inhibitor resistance in annual sedge. This is also the first report of ALS-resistance in a sedge species from a turfgrass system.
See more from this Division: C05 Turfgrass Science
See more from this Session: Turfgrass Science: I