INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

MULTIPLE RESISTANT SMOOTH PIGWEED
(Amaranthus hybridus (syn: quitensis))


Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)

Argentina, Córdoba
INTRODUCTION SMOOTH PIGWEED
Smooth Pigweed (Amaranthus hybridus (syn: quitensis)) is a dicot weed in the Amaranthaceae family.  In Argentina this weed first evolved multiple resistance (to 2 herbicide sites of action) in 2014 and infests Corn (maize), and Soybean.  Multiple resistance has evolved to herbicides in the Groups 2 (Legacy B), and Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G).  These particular biotypes are known to have resistance to glyphosate, and imazethapyr and they may be cross-resistant to other herbicides in the Groups 2 (Legacy B), and Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G).

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 20, 2015 )

Common NameSmooth Pigweed
SpeciesAmaranthus hybridus (syn: quitensis)
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
Herbicidesglyphosate, and imazethapyr
LocationArgentina, Córdoba
Year2014
Situation(s)Corn (maize), and Soybean
Contributors - (Alphabetically)Pablo Belluccini, and Diego Ustarroz 
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NOTES ABOUT THIS BIOTYPE

MECHANISM

A triple target-site mutation confers high levels of resistance to glyphosate in an Amaranthus quitensis population from Argentina   Sarah-Jane Hutchingsa, Eddie McIndoea, Ryan Carlinb, Wenjin Yub, Anushka Howella, Weining Gub, Wenling Wangb, Mike Langforda, Jo Mattocksa and Shiv-Shankar Kaunduna   a Syngenta, Jealott’s Hill International Research Centre, RG42 6EY Bracknell, UK b Syngenta, Research Triangle Park, NC USA   E:mail: sarah-jane.hutchings@syngenta.com

Resistance to glyphosate has evolved and is quickly spreading in Amaranthus quitensis due to excessive use of the EPSPS-inhibiting herbicide in Argentinian soybean production systems.  Here, we confirmed resistance to glyphosate and determined the mechanism involved in an A. quitensis population (AMAQU-R) from Santa Fe Province, Argentina. AMAQU-R plants survived glyphosate rates as high as 48 kg ai/ha, whereas individuals from the sensitive populations (AMAQU-S1 and AMAQU-S2) were killed at 750 g ai/ha or below. Differential glyphosate uptake, movement or metabolism was not associated with resistance in AMAQU-R and only a small average relative increase (1.94) in EPSPS gene copy number/expression was detected in AMAQU-R.  Three linked EPSPS mutations were identified around the binding site of glyphosate in AMAQU-R. These comprised T102I and P106S amino acid substitutions documented to confer high levels of glyphosate resistance, as well as a novel A103V target-site mutation. A 3.5-fold more tolerance to glyphosate was observed for the TIAVPS mutant compared to the double TIPS strain following heterologous gene expression and enzyme analysis. The triple glyphosate resistance mutations may explain the rapid spread of A. quitensis in Argentina and could be a real threat for neighbouring countries under similar glyphosate selection pressure.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Smooth Pigweed biotype with this Smooth Pigweed 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, 9 resistant Smooth Pigweed 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 Smooth Pigweed 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
DIEGO USTARROZ
Research Associate
Inta
Sección Malezas
Ruta 9 Km 636 Manfredi
Córdoba Argentina.
Manfredi, 5688, Córdoba
Argentina
Email Diego Ustarroz

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, and Diego Ustarroz for providing detailed information.
Herbicide Resistant Smooth Pigweed Globally
(Amaranthus hybridus (syn: quitensis))
Herbicide Resistant Smooth Pigweed Globally
(Amaranthus hybridus (syn: quitensis))
Drag a column header and drop it here to group by that column
Herbicide Resistant Smooth Pigweed Globally
(Amaranthus hybridus (syn: quitensis))
#CountryFirstYearSituationActive IngredientsSite of Action
1 ArgentinaArgentina 1996 Soybean chlorimuron-ethyl, and imazethapyr 48 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5099
2 ArgentinaArgentina 2013 Soybean glyphosate 48 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed6757
3 ArgentinaArgentina 2014 Corn (maize), and Soybean glyphosate, and imazethapyr 48 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed9948
4 ArgentinaArgentina 2016 Soybean 2,4-D, dicamba, 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)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed17107
5 ArgentinaArgentina 2016 Soybean 2,4-D, and dicamba 48 Auxin Mimics ( HRAC Group 4 (Legacy O)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed17108
6 ArgentinaArgentina 2021 Soybean fomesafen 48 Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed23243
7 BoliviaBolivia 2002 Soybean chlorimuron-ethyl, imazamox, imazethapyr, and oxasulfuron 4 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5242
8 BoliviaBolivia 2005 Soybean fomesafen, lactofen, and sulfentrazone 4 Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5411
9 BrazilBrazil 2018 Soybean chlorimuron-ethyl, and glyphosate 5 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed18184
10 Canada (Ontario) CanadaOntario2004 Corn (maize) bentazon, and bromoxynil 7 PSII inhibitors - Histidine 215 Binders ( HRAC Group 6 (Legacy C3)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5472
11 FranceFrance 1980 Corn (maize) atrazine 17 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed453
12 IsraelIsrael 1986 Cropland atrazine 23 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed101
13 ItalyItaly 1978 Corn (maize) atrazine 24 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed114
14 ItalyItaly 2018 Soybean imazamox, and thifensulfuron-methyl 24 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed27281
15 ParaguayParaguay 2022 Corn (maize), and Soybean chlorimuron-ethyl, and glyphosate 46 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed24252
16 South AfricaSouth Africa 1993 Corn (maize) atrazine 37 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed193
17 South AfricaSouth Africa 2024 Corn (maize), and Soybean glyphosate 37 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed27287
18 SpainSpain 1985 Corn (maize) atrazine 38 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed175
19 SwitzerlandSwitzerland 1982 Vegetables simazine 41 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed198
20 United States (Maryland) United StatesMaryland1972 Corn (maize), and Cropland atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed429
21 United States (Virginia) United StatesVirginia1976 Corn (maize) atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed273
22 United States (Delaware) United StatesDelaware1977 Corn (maize) atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed492
23 United States (North Carolina) United StatesNorth Carolina1980 Corn (maize) atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed262
24 United States (Pennsylvania) United StatesPennsylvania1980 Corn (maize) atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed264
25 United States (New Jersey) United StatesNew Jersey1980 Corn (maize) atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed494
26 United States (New York) United StatesNew York1980 Corn (maize) atrazine, metribuzin, and simazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5225
27 United States (Wisconsin) United StatesWisconsin1985 Corn (maize) atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed418
28 United States (Kentucky) United StatesKentucky1987 Corn (maize) atrazine, and simazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed489
29 United States (Kentucky) United StatesKentucky1992 Soybean chlorimuron-ethyl, flumetsulam, imazaquin, imazethapyr, nicosulfuron, primisulfuron-methyl, and thifensulfuron-methyl 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed490
30 United States (Illinois) United StatesIllinois1993 Corn (maize) atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed236
31 United States (Virginia) United StatesVirginia1994 Corn (maize), and Soybean imazaquin, and imazethapyr 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed278
32 United States (Illinois) United StatesIllinois1998 Soybean imazethapyr, and primisulfuron-methyl 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed7859
33 United States (Delaware) United StatesDelaware2000 Vegetables imazethapyr 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5160
34 United States (Illinois) United StatesIllinois2000 Corn (maize) atrazine, imazethapyr, and primisulfuron-methyl 45 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed7860
35 United States (Ohio) United StatesOhio2001 Soybean flumetsulam, and thifensulfuron-methyl 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5233
36 United States (Michigan) United StatesMichigan2002 Soybean chlorimuron-ethyl, imazamox, and thifensulfuron-methyl 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5170
37 UruguayUruguay 2022 Corn (maize), and Soybean glyphosate 73 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed24255
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