HRAC GROUP 2 (LEGACY B) RESISTANT ANNUAL SEDGE
(Cyperus compressus)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

United States, Alabama

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INTRODUCTION ANNUAL SEDGE Annual Sedge (Cyperus compressus) is a monocot weed in the Cyperaceae family.  In Alabama this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2015 and infests Turf.   Group 2 (Legacy B) herbicides are known as Inhibition of Acetolactate Synthase (Inhibition of Acetolactate Synthase ).  Research has shown that these particular biotypes are resistant to halosulfuron-methyl, imazapic, sulfometuron-methyl, and trifloxysulfuron-Na and they may be cross-resistant to other Group 2 (Legacy B) herbicides. The 'Group' letters/numbers that you see throughout this web site refer to the classification of herbicides by their site of action. To see a full list of herbicides and HRAC herbicide classifications click here.

QUIK STATS (last updated Jan 14, 2016 ) Common Name Annual Sedge Species Cyperus compressus Group Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B) Herbicides halosulfuron-methyl, imazapic, sulfometuron-methyl, and trifloxysulfuron-Na Location United States, Alabama Year 2015 Situation(s) Turf Contributors - (Alphabetically) Scott Mcelroy  Edit this Case  |  Add New Case of Resistance  |  Add Note

NOTES ABOUT THIS BIOTYPE DOSE RESPONSE Scott Mcelroy Patrick E. McCullough, Jialin Yu, J. Scott McElroy, S. Chen, H. Zhang, Timothy L. Grey, and Mark A. Czarnota (2016) ALS–Resistant Annual Sedge (Cyperus compressus) Confirmed in Turfgrass. Weed Science: January-March 2016, Vol. 64, No. 1, pp. 33-41. 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. Edit this Note  |  Add New Note

ACADEMIC ASPECTS Confirmation Tests Greenhouse, and Laboratory trials comparing a known susceptible Annual Sedge biotype with this Annual Sedge biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.   Genetics Genetic studies on HRAC Group 2 resistant Annual Sedge have not been reported to the site.  There may be a note below or an article discussing the genetics of this biotype in the Fact Sheets and Other Literature   Mechanism of Resistance Studies on the mechanism of resistance of Group 2 (Legacy B) resistant Annual Sedge from Alabama indicate that resistance is due to an altered target site.  There may be a note below or an article discussing the mechanism of resistance in the Fact Sheets and Other Literature   Relative Fitness There is no record of differences in fitness or competitiveness of these resistant biotypes when compared to that of normal susceptible biotypes.  If you have any information pertaining to the fitness of Group 2 (Legacy B) resistant Annual Sedge from Alabama please update the database.   Edit Case  |  Add Note  |  Add Article  |  Add New Case  |  Help

CONTRIBUTING WEED SCIENTISTS SCOTT MCELROY Assistant Professor Auburn University Depart. Of Agronomy And Soils 201 Funchess Hall Auburn, 36830, Alabama United States Email Scott Mcelroy Web   : Web Site Link

ACKNOWLEDGEMENTS The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Alabama have been instrumental in providing you this information. Particular thanks is given to Scott Mcelroy for providing detailed information.

Herbicide Resistant Annual Sedge Globally (Cyperus compressus) Herbicide Resistant Annual Sedge Globally (Cyperus compressus) Drag a column header and drop it here to group by that column Herbicide Resistant Annual Sedge Globally (Cyperus compressus) # Country Country StateName FirstYear Situation Active Ingredients CountryID Site of Action WeedID Species CommonName ResistID 1 United States (Alabama) United States Alabama 2015 Turf halosulfuron-methyl, imazapic, sulfometuron-methyl, and trifloxysulfuron-Na 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B) 329 Cyperus compressus Annual Sedge 11012

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McCullough, P. E., J. Yu, J. S. McElroy, S. Chen, H. Zhang, T. L. Grey, and M. A. Czarnota. 2016. ALS–​resistant ​annual ​sedge (Cyperus compressus) ​confirmed in ​turf grass.. Weed Science 64 : 41 - .

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..

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