INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

MULTIPLE RESISTANT PLUMELESS THISTLE
(Carduus acanthoides)

Multiple Resistance: 2 Sites of Action
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
Auxin Mimics HRAC Group 4 (Legacy O)

Argentina
INTRODUCTION PLUMELESS THISTLE
Plumeless Thistle (Carduus acanthoides) is a dicot weed in the Asteraceae family.  In Argentina this weed first evolved multiple resistance (to 2 herbicide sites of action) in 2019 and infests Corn (maize), and Soybean.  Multiple resistance has evolved to herbicides in the Groups 9 (Legacy G), and Auxin Mimics HRAC Group 4 (Legacy O).  These particular biotypes are known to have resistance to 2,4-D, and glyphosate and they may be cross-resistant to other herbicides in the Groups 9 (Legacy G), and Auxin Mimics HRAC Group 4 (Legacy O).

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 Oct 01, 2019 )

Common NamePlumeless Thistle
SpeciesCarduus acanthoides
GroupInhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)

Auxin Mimics HRAC Group 4 (Legacy O)
Herbicides2,4-D, and glyphosate
LocationArgentina
Year2019
Situation(s)Corn (maize), and Soybean
Contributors - (Alphabetically)Pablo Belluccini, Rafael De Prado, Valentín Gentiletti, and Candelario Palma-Bautista 
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Plumeless Thistle biotype with this Plumeless Thistle 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 9, 4 resistant Plumeless Thistle 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 multiple resistant Plumeless Thistle from Argentina please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

PABLO BELLUCCINI
Weed Scientist
INTA Marcos Juarez
Weeds
Route 12 km. 3 (2580)
Cordoba, Cordoba
Argentina
Email Pablo Belluccini
RAFAEL DE PRADO
Weed Scientist
Universidad De Cordoba
Qvimica Agricola Y Edafologa
E T S Ingenieros Agronomos
PO Box 119
Cordoba, E-14080, Andalusia
Spain
Email Rafael De Prado
VALENTÍN GENTILETTI
Ingeniero Agrónomo
Aapresid
Qvimica Agricola Y Edafologa
E T S Ingenieros Agronomos
9 de Julio 945
Camilo Aldao, X2585ACS, Córdoba
Argentina
Email Valentín Gentiletti
CANDELARIO PALMA-BAUTISTA
Investigador Posdoctoral
Universidad Autónoma Chapingo
Departamento de Parasitología Agrícola
Campus Central
Carretera México – Texcoco Km 38.5 Texcoco, México CP 56230
Texcoco, 56230, Estado de México
Mexico
Email Candelario Palma-Bautista

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Argentina have been instrumental in providing you this information. Particular thanks is given to Pablo Belluccini, Rafael De Prado, Valentín Gentiletti, and Candelario Palma-Bautista for providing detailed information.
Herbicide Resistant Plumeless Thistle Globally
(Carduus acanthoides)
Herbicide Resistant Plumeless Thistle Globally
(Carduus acanthoides)
Drag a column header and drop it here to group by that column
Herbicide Resistant Plumeless Thistle Globally
(Carduus acanthoides)
#CountryFirstYearSituationActive IngredientsSite of Action
1 ArgentinaArgentina 2019 Corn (maize), and Soybean 2,4-D, and glyphosate 48 Multiple Resistance: 2 Sites of Action
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
Auxin Mimics ( HRAC Group 4 (Legacy O)
 		348Carduus acanthoidesPlumeless Thistle18173
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Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Friday, October 31, 2025 .  Available  www.weedscience.org Copyright © 1993- 2025 WeedScience.org All rights reserved. Fair use of this material is encouraged. Proper citation is requested.