International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
GROUP B/2 RESISTANT SPINY SOWTHISTLE
(Sonchus asper)


ALS inhibitors (B/2)

Canada, Alberta
INTRODUCTION SPINY SOWTHISTLE
Spiny Sowthistle (Sonchus asper) is a dicot weed in the Asteraceae family.  In Alberta this weed first evolved resistance to Group B/2 herbicides in 1996 and infests Pastures, and 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 chlorsulfuron, metsulfuron-methyl, thifensulfuron-methyl, 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 Jan 18, 2014 )

Common NameSpiny Sowthistle
SpeciesSonchus asper
GroupALS inhibitors (B/2)
Herbicideschlorsulfuron, metsulfuron-methyl, thifensulfuron-methyl, and tribenuron-methyl
LocationCanada, Alberta
Year1996
Situation(s)Pastures, and Spring Barley
Contributors - (Alphabetically)John O'Donovan 
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NOTES ABOUT THIS BIOTYPE

AREAS FOUND

John O'Donovan
Central Alberta, near Ponoka

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GENERAL

John O'Donovan
The fields had a long history of chlorsulfuron and metsulfuron-methyl use. In greenhouse trials, the sow-thistle was also resistant to thifensulfuron-methyl and tribenuron-methyl, but not to several other herbicides tested.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Spiny Sowthistle biotype with this Spiny Sowthistle 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 Group B/2 resistant Spiny Sowthistle 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 Spiny Sowthistle from Alberta 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 Spiny Sowthistle from Alberta please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

JOHN O'DONOVAN
Agriculture And Agri-Food Canada
Universidad Nacional De Mar Del Plata
Ruta Nacional 226, Km 73.5,
Beaverlodge, T0H 0C0, Alberta
Canada
Email John O'Donovan

ACKNOWLEDGEMENTS

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 John O'Donovan for providing detailed information.
Herbicide Resistant Spiny Sowthistle Globally
(Sonchus asper)
Herbicide Resistant Spiny Sowthistle Globally
(Sonchus asper)
Drag a column header and drop it here to group by that column
Herbicide Resistant Spiny Sowthistle Globally
(Sonchus asper)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Canada (Alberta) CanadaAlberta1996 Pastures, and Spring Barley chlorsulfuron, metsulfuron-methyl, thifensulfuron-methyl, and tribenuron-methyl 7 ALS inhibitors (B/2)
163Sonchus asperSpiny Sowthistle1153
2 FranceFrance 1980 Corn (maize) atrazine 17 Photosystem II inhibitors (C1/5)
163Sonchus asperSpiny Sowthistle473
3 FranceFrance 2015 Chicory rimsulfuron 17 ALS inhibitors (B/2)
163Sonchus asperSpiny Sowthistle14058
4 NorwayNorway 2006 Spring Barley, and Spring wheat iodosulfuron-methyl-sodium, and tribenuron-methyl 31 ALS inhibitors (B/2)
163Sonchus asperSpiny Sowthistle10976
5 United States (Washington) United StatesWashington2000 Lentils, and Wheat imazamox, and thifensulfuron-methyl 45 ALS inhibitors (B/2)
163Sonchus asperSpiny Sowthistle5186
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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Friday, June 23, 2017 .  Available  www.weedscience.org
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