First report of resistance to acetolactate-synthase-inhibiting herbicides in yellow nutsedge (Cyperus esculentus): confirmation and characterization

Pest Manag Sci. 2015 Sep;71(9):1274-80. doi: 10.1002/ps.3922. Epub 2014 Nov 10.


Background: Yellow nutsedge is one of the most problematic sedges in Arkansas rice, requiring the frequent use of halosulfuron (sulfonylurea) for its control. In the summer of 2012, halosulfuron at 53 g ha(-1) (labeled field rate) failed to control yellow nutsedge. The level of resistance to halosulfuron was determined in the putative resistant biotype, and its cross-resistance to other acetolactate synthase (ALS) inhibitors from four different herbicide families. ALS enzyme assays and analysis of the ALS gene were used to ascertain the resistance mechanism.

Results: None of the resistant plants was killed by halosulfuron at a dose of 13 568 g ha(-1) (256× the field dose), indicating a high level of resistance. Based on the whole-plant bioassay, the resistant biotype was not controlled by any of the ALS-inhibiting herbicides (imazamox, imazethapyr, penoxsulam, bispyribac, pyrithiobac-sodium, bensulfuron and halosulfuron) tested at the labeled field rate. The ALS enzyme from the resistant biotype was 2540 times less responsive to halosulfuron than the susceptible biotype, and a Trp574 -to-Leu substitution was detected by ALS gene sequencing using the Illumina HiSeq.

Conclusion: The results suggest a target-site alteration as the mechanism of resistance in yellow nutsedge, which accounts for the cross-resistance to other ALS-inhibiting herbicide families.

Keywords: ALS assay; ALS gene sequencing; Cyperus esculentus; Illumina HiSeq; herbicide resistance mechanism; yellow nutsedge.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetolactate Synthase / antagonists & inhibitors*
  • Acetolactate Synthase / genetics
  • Arkansas
  • Cyperus / drug effects*
  • Cyperus / enzymology
  • Herbicide Resistance / genetics*
  • Herbicides / pharmacology*
  • Mutation
  • Polymorphism, Single Nucleotide
  • Sulfonylurea Compounds / pharmacology*


  • Herbicides
  • Sulfonylurea Compounds
  • halosulfuron methyl
  • Acetolactate Synthase