ALS–Resistant Annual Sedge (Cyperus compressus) Confirmed in Turfgrass. Issue 1 (March 2016)

• Record Type: Journal Article
• Authors: McCullough, Patrick E.; Yu, Jialin; McElroy, J. Scott; Chen, S.; Zhang, H.; Grey, Timothy L.; Czarnota, Mark A.
• Is Part Of: Weed science. Volume 64: Issue 1(2016)
• Page Start: 33
• Page End: 41
• Publication Date: 2016-03
• Subjects: Glufosinate, -- glyphosate, -- halosulfuron, -- imazapic, -- MSMA, -- sulfentrazone, -- sulfosulfuron, -- trifloxysulfuron, -- annual sedge, Cyperus compressus L., -- bermudagrass, Cynodon dactylon L. (Pers.) × Cynodon transvaalensis Burtt-Davy; Efficacy, -- mutation, -- sedge, -- sod, -- turf, -- sulfonylurea; 632.505
• DOI: 10.1614/WS-D-15-00094.1
• Languages: English
• ISSNs: 0043-1745

Abstract

Abstract : Acetolactate synthase (ALS) inhibitors are widely used for POST control of sedges 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. Research was conducted to evaluate the resistance level of this biotype to halosulfuron, efficacy of ALS-inhibiting herbicides and other mechanisms of action for control, and the molecular and physiological basis for resistance. In greenhouse experiments, the halosulfuron rate required to reduce shoot biomass 50% in comparison with the nontreated at 8 wk after treatment (WAT) were 8 and > 1, 120 g ai ha −1 for the S (susceptible) and R biotypes, respectively. Imazapic, sulfosulfuron, and trifloxysulfuron reduced biomass of the S biotype greater than 60% at 8 WAT, but biomass was reduced less than 20% for the R biotype. Glufosinate, glyphosate, MSMA, and sulfentrazone reduced shoot biomass of the R biotype by 93, 86, 97, and 45%, respectively. In laboratory experiments, the halosulfuron concentration required to inhibit ALS activity by 50% in excised leaf tissues was 5.8 and > 1, 000 μM 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 and herbicide resistance in a sedge species from a turfgrass system.