International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Cyperus brevifolius)

ALS inhibitors (B/2)

Japan, Kagawa, Saga, Shizuoka, Yamanashi
Shortleaf Spikesedge (Cyperus brevifolius) is a monocot weed in the Cyperaceae family.  In Japan this weed first evolved resistance to Group B/2 herbicides in 2010 and infests Golf courses.   Group B/2 herbicides are known as ALS inhibitors (Inhibition of acetolactate synthase ALS (acetohydroxyacid synthase AHAS)).  Research has shown that these particular biotypes are resistant to bensulfuron-methyl, and flazasulfuron and they may be cross-resistant to other Group B/2 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 08, 2014 )

Common NameShortleaf Spikesedge
SpeciesCyperus brevifolius
GroupALS inhibitors (B/2)
Herbicidesbensulfuron-methyl, and flazasulfuron
LocationJapan, Kagawa, Saga, Shizuoka, Yamanashi
Situation(s)Golf courses
Contributors - (Alphabetically)Satoshi Iwakami, and Akira Uchino 
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Akira Uchino
Okuno,J., S.Iwakami, A.Uchino, K.Tsuchida and M.Yokoyama (2015) Response to halosulfuron-methyl and Flazasulfuron and mutation of acetolactate synthase gene of Cyperus brevifolius survived in turf grass on golf course. Journal of Japan Society of Turfgrass Science 43, 159-162 (in Japanese with English summary).

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Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Shortleaf Spikesedge biotype with this Shortleaf Spikesedge biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.

Genetic studies on Group B/2 resistant Shortleaf Spikesedge 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 B/2 resistant Shortleaf Spikesedge from Japan please update the database.
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Weed Scientist
University of Tsukuba
Faculty of Life and Environmental Sciences
1-1-1 Tennoudai
Tsukuba, 305-8577, Ibaraki
Email Satoshi Iwakami
Weed Scientist
NARO Agricultural Research Center
Faculty of Life and Environmental Sciences
3-1-1 Kannondai
Tsukuba, 305-8666, Ibaraki
Email Akira Uchino


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Japan have been instrumental in providing you this information. Particular thanks is given to Satoshi Iwakami, and Akira Uchino for providing detailed information.
Herbicide Resistant Shortleaf Spikesedge Globally
(Cyperus brevifolius)
Herbicide Resistant Shortleaf Spikesedge Globally
(Cyperus brevifolius)
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Herbicide Resistant Shortleaf Spikesedge Globally
(Cyperus brevifolius)
#CountryFirstYearSituationActive IngredientsSite of Action
1 JapanJapan 2010 Golf courses bensulfuron-methyl, and flazasulfuron 25 ALS inhibitors (B/2)
303Cyperus brevifoliusShortleaf Spikesedge7798
Literature about Similar Cases

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