International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
MULTIPLE RESISTANT SMOOTH PIGWEED
(Amaranthus hybridus (syn: quitensis))


Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)

Brazil
INTRODUCTION SMOOTH PIGWEED
Smooth Pigweed (Amaranthus hybridus (syn: quitensis)) is a dicot weed in the Amaranthaceae family.  In Brazil this weed first evolved multiple resistance (to 2 herbicide sites of action) in 2018 and infests Soybean.  Multiple resistance has evolved to herbicides in the Groups B/2, and G/9.  These particular biotypes are known to have resistance to chlorimuron-ethyl, and glyphosate and they may be cross-resistant to other herbicides in the Groups B/2, and G/9.

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 Nov 28, 2019 )

Common NameSmooth Pigweed
SpeciesAmaranthus hybridus (syn: quitensis)
GroupALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
Herbicideschlorimuron-ethyl, and glyphosate
LocationBrazil
Year2018
Situation(s)Soybean
Contributors - (Alphabetically)Joao Da Silva, Claudia de Oliveira, Lúcio Lemes, Sandra Marisa Mathioni, Eduardo Ozorio, and Daniel Rosa 
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory 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 Group B, G/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

Studies on the mechanism of resistance of multiple resistant Smooth Pigweed from Brazil 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 multiple resistant Smooth Pigweed from Brazil please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

JOAO DA SILVA

Agronomy& Soils Dept
201 Funchess Hall,
Boa Vista, 3700882, Sete Lagoas
Brazil
Email Joao Da Silva
CLAUDIA DE OLIVEIRA
Research
Syngenta, Crop protection
Resistance Management
Br452 km142
Uberlândia, 38407049, Minas Gerais
Brazil
Email Claudia de Oliveira
LÚCIO LEMES
Herbicides Technical Manager
Syngenta Crop Protection
R&D LATAM
Av. Alexandre Cazelatto
2660.
Paulínia, 13.148-218, São Paulo
Brazil
Email Lúcio Lemes
SANDRA MARISA MATHIONI
Researcher
Syngenta Crop Science
Resistance Monitoring
Rodovia BR-452
Uberlândia, 38407049, Minas Gerais
Brazil
Email Sandra Marisa Mathioni
EDUARDO OZORIO
Researcher
Syngenta Proteção de Cultivos Ltda
Research and Development
Rua Coronel Dulcídio
368 - Apt. 42
Ponta Grossa, 84010280, Paraná
Brazil
Email Eduardo Ozorio
DANIEL ROSA
Resistance Management Manager
Syngenta
Resistance Management
BR 452, km 142
Uberlandia, 38408314, Minas Gerais
Brazil
Email Daniel Rosa
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Brazil have been instrumental in providing you this information. Particular thanks is given to Joao Da Silva, Claudia de Oliveira, Lúcio Lemes, Sandra Marisa Mathioni, Eduardo Ozorio, and Daniel Rosa 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 ALS inhibitors (B/2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5099
2 ArgentinaArgentina 2013 Soybean glyphosate 48 EPSP synthase inhibitors (G/9)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed6757
3 ArgentinaArgentina 2014 Corn (maize), and Soybean glyphosate, and imazethapyr 48 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed9948
4 ArgentinaArgentina 2016 Soybean 2,4-D, dicamba, and glyphosate 48 Multiple Resistance: 2 Sites of Action
EPSP synthase inhibitors (G/9)
Synthetic Auxins (O/4)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed17107
5 ArgentinaArgentina 2016 Soybean 2,4-D, and dicamba 48 Synthetic Auxins (O/4)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed17108
6 BoliviaBolivia 2002 Soybean chlorimuron-ethyl, imazamox, imazethapyr, and oxasulfuron 4 ALS inhibitors (B/2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5242
7 BoliviaBolivia 2005 Soybean fomesafen, lactofen, and sulfentrazone 4 PPO inhibitors (E/14)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5411
8 BrazilBrazil 2018 Soybean chlorimuron-ethyl, and glyphosate 5 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed18184
9 Canada (Ontario) CanadaOntario2004 Corn (maize) bentazon, and bromoxynil 7 PSII inhibitors (Nitriles) (C3/6)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5472
10 FranceFrance 1980 Corn (maize) atrazine 17 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed453
11 IsraelIsrael 1986 Cropland atrazine 23 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed101
12 ItalyItaly 1978 Corn (maize) atrazine 24 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed114
13 South AfricaSouth Africa 1993 Corn (maize) atrazine 37 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed193
14 SpainSpain 1985 Corn (maize) atrazine 38 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed175
15 SwitzerlandSwitzerland 1982 Vegetables simazine 41 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed198
16 United States (Maryland) United StatesMaryland1972 Corn (maize), and Cropland atrazine 45 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed429
17 United States (Virginia) United StatesVirginia1976 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed273
18 United States (Delaware) United StatesDelaware1977 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed492
19 United States (North Carolina) United StatesNorth Carolina1980 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed262
20 United States (Pennsylvania) United StatesPennsylvania1980 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed264
21 United States (New Jersey) United StatesNew Jersey1980 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed494
22 United States (New York) United StatesNew York1980 Corn (maize) atrazine, metribuzin, and simazine 45 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5225
23 United States (Wisconsin) United StatesWisconsin1985 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed418
24 United States (Kentucky) United StatesKentucky1987 Corn (maize) atrazine, and simazine 45 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed489
25 United States (Kentucky) United StatesKentucky1992 Soybean chlorimuron-ethyl, flumetsulam, imazaquin, imazethapyr, nicosulfuron, primisulfuron-methyl, and thifensulfuron-methyl 45 ALS inhibitors (B/2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed490
26 United States (Illinois) United StatesIllinois1993 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed236
27 United States (Virginia) United StatesVirginia1994 Corn (maize), and Soybean imazaquin, and imazethapyr 45 ALS inhibitors (B/2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed278
28 United States (Illinois) United StatesIllinois1998 Soybean imazethapyr, and primisulfuron-methyl 45 ALS inhibitors (B/2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed7859
29 United States (Delaware) United StatesDelaware2000 Vegetables imazethapyr 45 ALS inhibitors (B/2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5160
30 United States (Illinois) United StatesIllinois2000 Corn (maize) atrazine, imazethapyr, and primisulfuron-methyl 45 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
Photosystem II inhibitors (C1/5)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed7860
31 United States (Ohio) United StatesOhio2001 Soybean flumetsulam, and thifensulfuron-methyl 45 ALS inhibitors (B/2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5233
32 United States (Michigan) United StatesMichigan2002 Soybean chlorimuron-ethyl, imazamox, and thifensulfuron-methyl 45 ALS inhibitors (B/2)
12Amaranthus hybridus (syn: quitensis)Smooth Pigweed5170
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