INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 2 (LEGACY B) RESISTANT NEEDLE SPIKERUSH
(Eleocharis acicularis)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

South Korea
INTRODUCTION NEEDLE SPIKERUSH
Needle Spikerush (Eleocharis acicularis) is a monocot weed in the Cyperaceae family.  In South Korea this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2006 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 azimsulfuron, bensulfuron-methyl, cinosulfuron, cyclosulfamuron, ethoxysulfuron, halosulfuron-methyl, imazosulfuron, and 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 Jan 22, 2014 )

Common NameNeedle Spikerush
SpeciesEleocharis acicularis
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicidesazimsulfuron, bensulfuron-methyl, cinosulfuron, cyclosulfamuron, ethoxysulfuron, halosulfuron-methyl, imazosulfuron, and pyrazosulfuron-ethyl
LocationSouth Korea
Year2006
Situation(s)Rice
Contributors - (Alphabetically)Tae Seon Park 
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Needle Spikerush biotype with this Needle Spikerush 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 Needle Spikerush 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 Needle Spikerush from South Korea please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

TAE SEON PARK
Physiology Of Herbicide Action
National Institute Of Agricultural Science And Technology
Department Of Crop Protection
Dept of Plant Sciences
51 Campus Dr.,
Suweon, 441-707
South Korea
Email Tae Seon Park

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in South Korea have been instrumental in providing you this information. Particular thanks is given to Tae Seon Park for providing detailed information.
Herbicide Resistant Needle Spikerush Globally
(Eleocharis acicularis)
Herbicide Resistant Needle Spikerush Globally
(Eleocharis acicularis)
Drag a column header and drop it here to group by that column
Herbicide Resistant Needle Spikerush Globally
(Eleocharis acicularis)
#CountryFirstYearSituationActive IngredientsSite of Action
1 JapanJapan 2008 Rice bensulfuron-methyl, and pyrazosulfuron-ethyl 25 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
 		295Eleocharis acicularisNeedle Spikerush7766
2 South KoreaSouth Korea 2006 Rice azimsulfuron, bensulfuron-methyl, cinosulfuron, cyclosulfamuron, ethoxysulfuron, halosulfuron-methyl, imazosulfuron, and pyrazosulfuron-ethyl 27 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
 		295Eleocharis acicularisNeedle Spikerush7849
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Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Tuesday, November 4, 2025 .  Available  www.weedscience.org Copyright © 1993- 2025 WeedScience.org All rights reserved. Fair use of this material is encouraged. Proper citation is requested.