(Capsella bursa-pastoris)

ALS inhibitors (B/2)

Shepherd's-purse (Capsella bursa-pastoris) is a dicot weed in the Brassicaceae family.  In Denmark this weed first evolved resistance to Group B/2 herbicides in 2012 and infests Spring Barley.   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 florasulam, and tribenuron-methyl 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 May 12, 2014 )

Common NameShepherd's-purse
SpeciesCapsella bursa-pastoris
GroupALS inhibitors (B/2)
Herbicidesflorasulam, and tribenuron-methyl
Situation(s)Spring Barley
Contributors - (Alphabetically)Solvejg Mathiassen 
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Solvejg Mathiassen

April 2017 Update

Capsella bursa-pastoris

Still only one verified case. Reference: Reiss A. (2014):  Characterisation of a Capsella bursa- pastoris biotype resistant to ALS inhibitors, Master thesis, Department of Agroecology, Aarhus University

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Solvejg Mathiassen
ALS resistant CAPBP was sampled in 2012 in spring barley. The field was sprayed with sulfonylureas 4 of 5 preceding years and crops established by reduced tillage. The susceptibility to tribenuron and florasulam was examined in pot experiments with 6 doses, and compared to a susceptible reference. The results showed a high level of resistance to tribenuron (RI=75) and a low level of resistance to florasulam (4<RI<10).

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Solvejg Mathiassen
TSR analysis showed a heterozygous mutation at Trp-574 of the ALS gene.

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Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Shepherd's-purse biotype with this Shepherd's-purse 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 Shepherd's-purse 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

Studies on the mechanism of resistance of Group B/2 resistant Shepherd's-purse from Denmark indicate that resistance is due to an altered target site.  There may be a note below or an article discussing the mechanism of resistance in the Fact Sheets and Other Literature
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 Shepherd's-purse from Denmark please update the database.
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Senior Scientist
Aarhus University, Science and Technology
Dept. of Agroecology
P.o. Box 30
Slagelse, 4200, Slagelse Municipality
Email Solvejg Mathiassen


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Denmark have been instrumental in providing you this information. Particular thanks is given to Solvejg Mathiassen for providing detailed information.
Herbicide Resistant Shepherd's-purse Globally
(Capsella bursa-pastoris)
Herbicide Resistant Shepherd's-purse Globally
(Capsella bursa-pastoris)
Drag a column header and drop it here to group by that column
Herbicide Resistant Shepherd's-purse Globally
(Capsella bursa-pastoris)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Canada (Saskatchewan) CanadaSaskatchewan2008 Wheat imazamox, imazethapyr, thifensulfuron-methyl, and tribenuron-methyl 7 ALS inhibitors (B/2)
41Capsella bursa-pastorisShepherd's-purse5381
2 Canada (Alberta) CanadaAlberta2011 Wheat thifensulfuron-methyl, and tribenuron-methyl 7 ALS inhibitors (B/2)
41Capsella bursa-pastorisShepherd's-purse5623
3 ChinaChina 2009 Winter wheat tribenuron-methyl 9 ALS inhibitors (B/2)
41Capsella bursa-pastorisShepherd's-purse5502
4 DenmarkDenmark 2012 Spring Barley florasulam, and tribenuron-methyl 13 ALS inhibitors (B/2)
41Capsella bursa-pastorisShepherd's-purse8910
5 IsraelIsrael 2000 Roadsides imazapyr 23 ALS inhibitors (B/2)
41Capsella bursa-pastorisShepherd's-purse5465
6 NorwayNorway 2019 Wheat iodosulfuron-methyl-sodium 31 ALS inhibitors (B/2)
41Capsella bursa-pastorisShepherd's-purse18169
7 PolandPoland 1984 Orchards simazine 33 Photosystem II inhibitors (C1/5)
41Capsella bursa-pastorisShepherd's-purse166
8 United States (Oregon) United StatesOregon2007 Alfalfa hexazinone, and metribuzin 45 Photosystem II inhibitors (C1/5)
41Capsella bursa-pastorisShepherd's-purse5366
Literature about Similar Cases

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Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Saturday, March 6, 2021 .  Available Copyright © 1993- 2021 All rights reserved. Fair use of this material is encouraged. Proper citation is requested.