International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
HRAC GROUP 2 (LEGACY B) RESISTANT DISC WATERHYSSOP
(Bacopa rotundifolia)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

Malaysia
INTRODUCTION DISC WATERHYSSOP
Disc Waterhyssop (Bacopa rotundifolia) is a dicot weed in the Scrophulariaceae family.  In Malaysia this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2000 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 bensulfuron-methyl, metsulfuron-methyl, 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 Nov 12, 2012 )

Common NameDisc Waterhyssop
SpeciesBacopa rotundifolia
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicidesbensulfuron-methyl, metsulfuron-methyl, and pyrazosulfuron-ethyl
LocationMalaysia
Year2000
Situation(s)Rice
Contributors - (Alphabetically)M. Azmi, and Kazuyuki Itoh 
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NOTES ABOUT THIS BIOTYPE

HISTORY - FIRST CASE

Azmi Man
Reference: Weed species diversity and management practices in the Sekinchan Farm Block, Selangor's South West Project - a Highly Productive Rice Area in Malaysia. Proceedings 1, 19th Asian-Pacific Weed Science Conference, 17-21 March 2003, Manila, Philippines. pp. 174-184.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Disc Waterhyssop biotype with this Disc Waterhyssop 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 Disc Waterhyssop 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 Disc Waterhyssop from Malaysia please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

M. AZMI
Malaysian Agricultural Rice Research Institute
108 Sirius Place
Bertam Kepala Betas, 13200, Penang
Malaysia
KAZUYUKI ITOH
Professor
Kobe University
Graduate School of Agricultural Science
１-１ Rokkodaicho
Kobe, 657-0013, Hyogo
Japan
Email Kazuyuki Itoh

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Malaysia have been instrumental in providing you this information. Particular thanks is given to M. Azmi, and Kazuyuki Itoh for providing detailed information.
Herbicide Resistant Disc Waterhyssop Globally
(Bacopa rotundifolia)
Herbicide Resistant Disc Waterhyssop Globally
(Bacopa rotundifolia)
Drag a column header and drop it here to group by that column
Herbicide Resistant Disc Waterhyssop Globally
(Bacopa rotundifolia)
#CountryFirstYearSituationActive IngredientsSite of Action
1 JapanJapan 2007 Rice bensulfuron-methyl, imazosulfuron, and pyrazosulfuron-ethyl 25 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
 		213Bacopa rotundifoliaDisc Waterhyssop7800
2 MalaysiaMalaysia 2000 Rice bensulfuron-methyl, metsulfuron-methyl, and pyrazosulfuron-ethyl 28 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
 		213Bacopa rotundifoliaDisc Waterhyssop5206
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