International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Rotala indica var. uliginosa)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

Japan, Akita
Kikashigusa (Rotala indica var. uliginosa) is a dicot weed in the Lythraceae family.  In Japan this weed first evolved resistance to Group 2 (Legacy B) herbicides in 1997 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 Dec 28, 2013 )

Common NameKikashigusa
SpeciesRotala indica var. uliginosa
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
LocationJapan, Akita
Contributors - (Alphabetically)Kazuyuki Itoh 
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Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Kikashigusa biotype with this Kikashigusa 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 HRAC Group 2 resistant Kikashigusa 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 Kikashigusa from Japan please update the database.
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Kobe University
Graduate School of Agricultural Science
1-1 Rokkodaicho
Kobe, 657-0013, Hyogo
Email Kazuyuki Itoh


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 Kazuyuki Itoh for providing detailed information.
Herbicide Resistant Kikashigusa Globally
(Rotala indica var. uliginosa)
Herbicide Resistant Kikashigusa Globally
(Rotala indica var. uliginosa)
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Herbicide Resistant Kikashigusa Globally
(Rotala indica var. uliginosa)
#CountryFirstYearSituationActive IngredientsSite of Action
1 JapanJapan 1997 Rice pyrazosulfuron-ethyl 25 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
214Rotala indica var. uliginosaKikashigusa5144
Literature about Similar Cases

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