<b>HRAC Group 2</b> <font size='2'> (Legacy B) </font> resistant Cyperus difformis from United States, Arkansas

International Survey of Herbicide-Resistant Weeds

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Thursday, October 31, 2024

HRAC GROUP 2 (LEGACY B) RESISTANT SMALLFLOWER UMBRELLA SEDGE
(Cyperus difformis)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

United States, Arkansas

INTRODUCTION		SMALLFLOWER UMBRELLA SEDGE
Smallflower Umbrella Sedge (Cyperus difformis) is a monocot weed in the Cyperaceae family. In Arkansas this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2010 and infests Rice. 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 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 Jul 29, 2011 )
Common Name	Smallflower Umbrella Sedge
Species	Cyperus difformis
Group	Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicides	halosulfuron-methyl
Location	United States, Arkansas
Year	2010
Situation(s)	Rice
Contributors - (Alphabetically)	Jason Norsworthy
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Smallflower Umbrella Sedge biotype with this Smallflower Umbrella 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 Smallflower Umbrella 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

The mechanism of resistance for this biotype is either unknown or has not been entered in the database. If you know anything about the mechanism of resistance for this biotype then please update the database.

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 Smallflower Umbrella Sedge from Arkansas please update the database.

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CONTRIBUTING WEED SCIENTISTS

JASON NORSWORTHY

Professor University Of Arkansas Department Of Crop Soil, And Environmental Sciences 1366 West Altheimer Drive Williams Hall Fayetteville, 72704, Arkansas United States Email Jason Norsworthy Web : Web Site Link

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

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Herbicide Resistant Smallflower Umbrella Sedge Globally
(Cyperus difformis)

Country

FirstYear

Situation

Active Ingredients

Site of Action

Australia (New South Wales )

1994

Rice

bensulfuron-methyl

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Brazil

2000

Rice

cyclosulfamuron, and pyrazosulfuron-ethyl

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Greece

2009

Rice

azimsulfuron, and halosulfuron-methyl

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

India

2017

Rice

bispyribac-sodium

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Italy

1999

Rice

azimsulfuron, bensulfuron-methyl, and cinosulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Portugal

2023

Rice

bentazon, and penoxsulam

Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
PSII inhibitors - Histidine 215 Binders ( HRAC Group 6 (Legacy C3)

South Korea

2002

Rice

azimsulfuron, bensulfuron-methyl, cinosulfuron, cyclosulfamuron, ethoxysulfuron, halosulfuron-methyl, imazosulfuron, and pyrazosulfuron-ethyl

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Spain

2000

Rice

bensulfuron-methyl, and penoxsulam

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Turkey

2010

Rice

azimsulfuron, bensulfuron-methyl, bispyribac-sodium, and penoxsulam

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

United States (California)

1993

Rice

bensulfuron-methyl

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

United States (Arkansas)

2010

Rice

halosulfuron-methyl

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

United States (California)

2013

Rice

propanil

PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)

Literature about Similar Cases

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Ntoanidou, S., N. Kaloumenos, G. Diamantidis, P. Madesis, and I. Eleftherohorinos. 2016. Molecular basis of Cyperus difformis cross-resistance to ALS-inhibiting herbicides. . Pesticide Biochemistry and Physiology 127 : 38 - 45.

Applications of 64 times higher rates of azimsulfuron and halosulfuron-methyl failed to reduce by 50% growth of 10 putative resistant (R) Cyperus difformis (smallflower umbrella-sedge) populations collected from rice fields located in Northern Greece. However, the growth rate of the susceptible (S) population was reduced by 50% by 1/4 of the recommended rate of both herbicides. The als gene sequencing identified point mutations at Pro-197 position, leading to amino acid substitution by Ala or Ser of the ALS enzyme. The in vitro activity of the ALS enzyme indicated that the I₅₀ values (herbicide concentration required for 50% reduction of the ALS activity) ranged from 10.7 to 55.5 μM azimsulfuron and from 6.7 to 50.6 μM halosulfuron-methyl, whereas the respective values for the S population were 0.09 and 0.11 μM. These results strongly support that cross-resistance of 10 C. difformis populations was due to point mutations of the als gene, which resulted in a less-sensitive ALS enzyme. This study reports the presence of a 1240 bp intron in the C. difformis als gene with the Pro-197 point mutations near the splice junction..

Tehranchian, P., D. S. Riar, J. K. Norsworthy, V. Nandula, S. McElroy, S. Chen, and R. C. Scott. 2015. ALS-resistant smallflower umbrella sedge (Cyperus difformis) in Arkansas rice: physiological and molecular basis of resistance. Weed Science 63 : 561 - 568.

Smallflower umbrella sedge is a problematic weed in direct-seeded rice in the midsouthern United States. It recently has evolved resistance to the acetolactate synthase (ALS) –inhibiting herbicide halosulfuron in Arkansas rice. Studies were conducted (1) to determine if the resistant biotype is cross resistant to other ALS-inhibiting herbicides, (2) to evaluate alternative herbicide control options, and (3) to determine the mechanism of resistance. Whole-plant bioassay revealed that halosulfuron-resistant plants were not controlled by bispyribac–sodium, imazamox, and penoxsulam at the labeled field rate of each herbicide. The level of resistance to these herbicides, based on the lethal dose needed to kill 50% of plants (LD₅₀) was ≥ 15-fold compared to a susceptible biotype. Both biotypes were controlled >96% with bentazon and propanil and ≤ 23% with quinclorac, thiobencarb, and 2,4-D. Hence, effective control measures exist; albeit, the number of herbicide options appear limited. Based on in vitro ALS enzyme assays, altered target site is the mechanism of resistance to halosulfuron and imazamox. Massively parallel sequencing with the use of the Illumina HiSeq detected an amino acid substitution of Pro₁₉₇-to-His in the resistant biotype that is consistent with ALS-inhibiting herbicide resistance in other weed species..

H. Mennan, E. Kaya-Altop, S. Rasa, J.C. Streibig, D. Yatmaz, U. Budak, D. Sariaslan. 2013. Resistance to ACCase and ALS inhibiting herbicides in cereals in Turkey; What have we learned?. EWRS 16th SYMPOSIUM, Samsun 2013 : .

The herbicides are very effective tools for controlling weeds but their extensive use over time has resulted in evaluation of weed resistance to herbicides with different modes of action. ACCase and ALS inhibiting herbicides have been used extensively in winter wheat and rice fields to control grass and broadleaved weeds since last two decades in Turkey. Recently, many growers in various area of Turkey complained for reduced control ofBifora radiansandGalium aparinein winter cereals, andEchinochloa spp., andCyperus difformisin water seeding rice after use of ALS and ACCase inhibitor herbicides. Therefore, the aim of this study are to understand the occurrence and frequency of resistant biotypes of these species to ACCase and ALS inhibiting herbicides; does the mechanism of resistance are target site (TSR) or non-target site resistance (NTSR), risk assessment of herbicides history in evaluation of resistance and how crop rotation reduce selection for resistance? Forty-three rice fields were sampled randomly in 2005 to confirm the existence of cross and multiple herbicide resistance ofE. oryzoides,E. crus-galliandC. difformisinvolving ALS (penoxsulam, bispyribac-sodium) and ACCase Inhibitor (cyhalofob-butyl). The same and more fields re-sampled in 2011. In addition to that, greenhouse experiments were conducted from 1995 to 2011 to monitor possible resistance populations of B. radians andG. aparineto ALS inhibitor (chlorsulfuron and tribenuron-methyl) sampled from 13 winter wheat fields. A log-logistic dose-response curve was fitted to greenhouse data ofE. oryzoidesto obtain ED₉₀. On the basis of those data, resistance to ALS inhibitors was detected in 2 accessions in 2005. On the other hand, allE. oryzoidesaccessions were susceptible to ACCase Inhibitor in the same year. The effective dose response level of ED₉₀resulted in 36 and 9 resistant accessions to ALS and ACCase, respectively after re-sampling from same fields in 2011. Most of E. crus-galli accessions were effectively controlled with penoxsulam and cyhalofob-butyl in 2005. But, 4 accessions did not controlled with bispyribac-sodium and these accessions were characterized as resistant. The number of resistant accession significantly increased in 2011 and reached almost 75% in both inhibitors. Of the 43 C. difformis populations tested, 11 survived after treatments of penoxsulam and bispyribac-sodium in 2005. But, the application of four times recommended rate of these herbicides resulted only 3-5% fresh weight reduction of 40 C. difformis populations in 2011. The remaining 3 population with no evidence of penoxsulam and bispyribac-sodium resistance were controlled with almost double dose of these herbicides. A significant proportion of the populations in all species were found to be non-target site resistant..

E. Kaya–Altop, H. Mennan. 2013. Determination of ALS herbicides resistance biotypes ofCyperus difformisL. (smallflower umbrella sedge) in rice growing areas by molecular and bioassay methods. EWRS 16th SYMPOSIUM, Samsun 2013 : .

Weed control has been a major concern of growers since the beginning of rice (Oryza sativa) production in Turkey as well as other countries. Continuous use of a herbicide or herbicides with the same mode of action leads to the development of herbicide resistance in weed population. Rice is seldom rotated with other crops in many part of Turkey, and the few available grass herbicides have been used continuously to control weed species. The aim of this study were to determine resistance mechanism to ALS inhibiting herbicide ofC. difformis populations.C. difformispopulations had been collected from 646 different locations in rice fields of Marmara and Black Sea region. First , this populations were tested for possible resistance to azimsulfuron, bensulfuron methyl, bispyricac-sodium and penoxsulam at recommended doses in the greenhouse. Some accession exhibited the highest survival to the treatment with field rates of these herbicides. The Weibull dose-response curve, an asymmetric sigmoid curve was fitted to data to obtain ED₉₀in R program..

E. Kaya–Altop, H. Mennan. 2013. Determination of ALS-Accase Herbicides Resistance Biotypes by Molecular and Bioassay Methods and Genetic Diversity of Some Important Weed Species in Rice Growing Areas. TUBITAK TOVAG PROJECT REPORT : .

Rice is an important crop for Turkey, but its current production is so low that yearly 100-150 tons are still imported. Weed control has been a major concern of growers since the beginning ofOryza sativaproduction in Turkey as well as other countries. Continuous use of a herbicide or herbicides with the same mechanism of action leads to the development of herbicides resistance in weed population. Rice is seldom rotated with other crops in many part of Turkey, and the few available grass herbicides have been used continuously to controlEchinochloaspecies. Recently, farmers have complained of unacceptable control ofE. oryzoidesandE. crus-galliin rice by herbicides that previously controlled them. The taxonomic complexity of Echinochloa species are other problem. Conventionally identification of this genus is sometimes difficult because of the morphological diversity shown by the genus. Molecular techniques have opened new possibilities for taxonomic researches, especially for the species which are not well characterized morphologically. Seed samples ofE. oryzoides, E. cruss-galli,C. difformisandA. plantago-aquaticahad been collected from 679 fields randomly including areas where control problems had been detected. Firstfull,Echinochloaspecies were idifiefed based on moleculer techniques. As a result of this study 465, 124 and 90 accessions were identified asE. oryzoides, E. cruss-galliandEchinochloaspp. respectively.E. oryzoides, E. crus-galli,C.difformisandA. plantago-aquaticawere tested for resistance to penoxulam, chylafob-butyl, bispyribac-sodium, bensulfuron-methyl and azimsulfuron at registration doses in greenhouse. Some accession exhibited the highest survival to treatment with field rates of these herbicides. The Weibull dose-response curve, an asymmetric sigmoid curve, was fitted to data to obtain ED₉₀in R program. Most ofEchinochloaaccessions tested did not controlled by ALS or ACCase inhibitor and they were accepted as a resistant population cross-resistance to ALS and ACCase Inhibitor. Similiar results were observed for C. difformisandA. plantago-aquatica. Most of their accessions were not control by ALS Inhibitor..

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