INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 2 (LEGACY B) RESISTANT FRAGRANT FLATSEDGE
(Cyperus odoratus)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

Venezuela, Portuguesa
INTRODUCTION FRAGRANT FLATSEDGE
Fragrant Flatsedge (Cyperus odoratus) is a monocot weed in the Cyperaceae family.  In Venezuela this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2014 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 pyrazosulfuron-ethyl 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.

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QUIK STATS (last updated Feb 24, 2015 )

Common NameFragrant Flatsedge
SpeciesCyperus odoratus
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicidespyrazosulfuron-ethyl
LocationVenezuela, Portuguesa
Year2014
Situation(s)Rice
Contributors - (Alphabetically)Aida Ortiz 
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ACADEMIC ASPECTS

Confirmation Tests

Field, and Greenhouse trials comparing a known susceptible Fragrant Flatsedge biotype with this Fragrant Flatsedge 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 Fragrant Flatsedge 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 Fragrant Flatsedge from Venezuela please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

AIDA ORTIZ
Professor
Universidad Central De Venezuela
Agronomia
Avenida Universidad. Campus Maracay
Maracay, 2101, Aragua
Venezuela
Email Aida Ortiz
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Venezuela have been instrumental in providing you this information. Particular thanks is given to Aida Ortiz for providing detailed information.
Herbicide Resistant Fragrant Flatsedge Globally
(Cyperus odoratus)
Herbicide Resistant Fragrant Flatsedge Globally
(Cyperus odoratus)
Drag a column header and drop it here to group by that column
Herbicide Resistant Fragrant Flatsedge Globally
(Cyperus odoratus)
#CountryFirstYearSituationActive IngredientsSite of Action
1 VenezuelaVenezuela 2014 Rice pyrazosulfuron-ethyl 80 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
 		317Cyperus odoratusFragrant Flatsedge8920
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HRAC Global Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Friday, October 9, 2026.  Available at  www.weedscience.org

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