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QUIK STATS (last updated Mar 08, 2023 )
NOTES ABOUT THIS BIOTYPE
This article is available online at https://doi.org/10.3390/agronomy10081133
Scarabel L., Farinati S., Sattin M. Occurrence of resistance to ALS inhibitors in European Cyperus esculentus L.: characterisation and implications for management. Agronomy 2020, 10, 1133.
Yellow nutsedge (C. esculentus) is a perennial geophyte and invasive weed which is very difficult to control in rice and other irrigated row crops. Acetolactate synthase (ALS) inhibitors are the most commonly used herbicides to control sedges in rice. Failure to control C. esculentus was recently reported in a rice field in north-western Italy. The resistance status of this C. esculentus population was determined through a whole-plant bioassay. The mechanism underlying the resistance was elucidated, and the available chemical and non-chemical control options were discussed. The population proved to be resistant to halosulfuron and azimsulfuron at the recommended field rate. The ALS trancripts amplified from resistant and susceptible plants revealed the presence of a Pro197-to-Arg amino acid substitution in resistant plants, indicating that the resistance mechanism is target-site mediated. This is the first confirmation of herbicide resistance in C. esculentus in Europe. Resistance management should be based on an integrated approach, through the combination of diversified cultural and agronomic practices that can limit its spread and propagation through tubers.
CONTRIBUTING WEED SCIENTISTS
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.