International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Galeopsis tetrahit)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

Canada, Alberta
Common Hempnettle (Galeopsis tetrahit) is a dicot weed in the Lamiaceae family.  In Alberta this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2006 and infests Cereals.   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 thifensulfuron-methyl, and tribenuron-methyl 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.

If we do not have a picture for this weed, or you can provide a better picture (scan, digital camera etc) please please e-mail it to us.

QUIK STATS (last updated Jan 14, 2008 )

Common NameCommon Hempnettle
SpeciesGaleopsis tetrahit
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicidesthifensulfuron-methyl, and tribenuron-methyl
LocationCanada, Alberta
Contributors - (Alphabetically)Hugh Beckie 
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Confirmation Tests

Greenhouse trials comparing a known susceptible Common Hempnettle biotype with this Common Hempnettle 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 Common Hempnettle 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 Common Hempnettle from Alberta please update the database.
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Professor of Crop Weed Science...Canadian Expat
University of Western Australia
Australian Herbicide Resistance Initiative
School of Agriculture and Environment
35 Stirling Highway
Crawley, 6009, Western Australia
Email Hugh Beckie


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Alberta have been instrumental in providing you this information. Particular thanks is given to Hugh Beckie for providing detailed information.
Herbicide Resistant Common Hempnettle Globally
(Galeopsis tetrahit)
Herbicide Resistant Common Hempnettle Globally
(Galeopsis tetrahit)
Drag a column header and drop it here to group by that column
Herbicide Resistant Common Hempnettle Globally
(Galeopsis tetrahit)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Canada (Manitoba) CanadaManitoba1995 Cereals, and Wheat metsulfuron-methyl 7 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
91Galeopsis tetrahitCommon Hempnettle476
2 Canada (Alberta) CanadaAlberta1998 Cereals, Cropland, Spring Barley, and Wheat dicamba, fluroxypyr, and MCPA 7 Auxin Mimics ( HRAC Group 4 (Legacy O)
91Galeopsis tetrahitCommon Hempnettle1154
3 Canada (Alberta) CanadaAlberta2006 Cereals thifensulfuron-methyl, and tribenuron-methyl 7 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
91Galeopsis tetrahitCommon Hempnettle5320
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