International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
GROUP B/2 RESISTANT REDROOT PIGWEED
(Amaranthus retroflexus)


ALS inhibitors (B/2)

Canada, Manitoba
INTRODUCTION REDROOT PIGWEED
Redroot Pigweed (Amaranthus retroflexus) is a dicot weed in the Amaranthaceae family.  In Manitoba this weed first evolved resistance to Group B/2 herbicides in 2002 and infests Wheat.   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 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 Aug 09, 2004 )

Common NameRedroot Pigweed
SpeciesAmaranthus retroflexus
GroupALS inhibitors (B/2)
Herbicidesflorasulam
LocationCanada, Manitoba
Year2002
Situation(s)Wheat
Contributors - (Alphabetically)Hugh Beckie 
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Redroot Pigweed biotype with this Redroot 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/2 resistant Redroot 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 Group B/2 resistant Redroot Pigweed from Manitoba please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

HUGH BECKIE
Research Scientist
Agriculture & Agri-Food Canada, Science & Technology Branch
Herbicide-Resistant & Novel-Trait Plants
107 Science Place
Saskatoon, S7N 0X2, Saskatchewan
Canada
Email Hugh Beckie

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Manitoba have been instrumental in providing you this information. Particular thanks is given to Hugh Beckie for providing detailed information.
Herbicide Resistant Redroot Pigweed Globally
(Amaranthus retroflexus)
Herbicide Resistant Redroot Pigweed Globally
(Amaranthus retroflexus)
Drag a column header and drop it here to group by that column
Herbicide Resistant Redroot Pigweed Globally
(Amaranthus retroflexus)
#CountryFirstYearSituationActive IngredientsSite of Action
1 BrazilBrazil 2011 Cotton atrazine, prometryn, and trifloxysulfuron-sodium 5 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed5734
2 BrazilBrazil 2012 Cotton pyrithiobac-sodium, and trifloxysulfuron-sodium 5 ALS inhibitors (B/2)
16Amaranthus retroflexusRedroot Pigweed5733
3 BrazilBrazil 2014 Cotton, and Soybean fomesafen 5 PPO inhibitors (E/14)
16Amaranthus retroflexusRedroot Pigweed13033
4 BulgariaBulgaria 1984 Corn (maize), Cropland, Grapes, and Orchards atrazine, metribuzin, and simazine 6 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed44
5 BulgariaBulgaria 1984 Cropland linuron 6 PSII inhibitor (Ureas and amides) (C2/7)
16Amaranthus retroflexusRedroot Pigweed45
6 Canada (Ontario) CanadaOntario1980 Corn (maize), and Cropland atrazine 7 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed61
7 Canada (Ontario) CanadaOntario1998 Corn (maize), Cropland, and Soybean imazethapyr, and thifensulfuron-methyl 7 ALS inhibitors (B/2)
16Amaranthus retroflexusRedroot Pigweed1161
8 Canada (Ontario) CanadaOntario2001 Carrots, and Vegetables linuron 7 PSII inhibitor (Ureas and amides) (C2/7)
16Amaranthus retroflexusRedroot Pigweed5125
9 Canada (Quebec) CanadaQuebec2001 Carrots linuron 7 PSII inhibitor (Ureas and amides) (C2/7)
16Amaranthus retroflexusRedroot Pigweed5126
10 Canada (Manitoba) CanadaManitoba2002 Wheat florasulam 7 ALS inhibitors (B/2)
16Amaranthus retroflexusRedroot Pigweed5222
11 Canada (Ontario) CanadaOntario2005 Corn (maize) bentazon, and bromoxynil 7 PSII inhibitors (Nitriles) (C3/6)
16Amaranthus retroflexusRedroot Pigweed5473
12 Canada (Saskatchewan) CanadaSaskatchewan2010 Wheat thifensulfuron-methyl, and tribenuron-methyl 7 ALS inhibitors (B/2)
16Amaranthus retroflexusRedroot Pigweed5628
13 ChinaChina 1990 Cropland atrazine 9 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed1141
14 ChinaChina 2017 Soybean acifluorfen-sodium, fluoroglycofen-ethyl, fomesafen, imazethapyr, and lactofen 9 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
PPO inhibitors (E/14)
16Amaranthus retroflexusRedroot Pigweed16078
15 Czech RepublicCzech Republic 1985 Corn (maize), Railways, Roadsides, and Sugar beets atrazine, cyanazine, prometryn, and terbutryn 12 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed77
16 FranceFrance 1980 Corn (maize) atrazine 17 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed455
17 GermanyGermany 1980 Corn (maize), Railways, and Roadsides atrazine, and fenuron 18 Multiple Resistance: 2 Sites of Action
Photosystem II inhibitors (C1/5)
PSII inhibitor (Ureas and amides) (C2/7)
16Amaranthus retroflexusRedroot Pigweed370
18 GermanyGermany 2012 Corn (maize) nicosulfuron 18 ALS inhibitors (B/2)
16Amaranthus retroflexusRedroot Pigweed6742
19 GreeceGreece 2000 Potatoes metribuzin 19 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed5058
20 IsraelIsrael 1991 Forests chlorsulfuron 23 ALS inhibitors (B/2)
16Amaranthus retroflexusRedroot Pigweed106
21 ItalyItaly 1999 Corn (maize), Soybean, and Sugar beets chloridazon = pyrazon, metamitron, and terbuthylazine 24 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed5115
22 ItalyItaly 2003 Soybean imazamox, imazethapyr, nicosulfuron, oxasulfuron, and thifensulfuron-methyl 24 ALS inhibitors (B/2)
16Amaranthus retroflexusRedroot Pigweed5248
23 PolandPoland 1991 Orchards, and Sugar beets atrazine, and metamitron 33 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed164
24 SerbiaSerbia 2002 Soybean imazethapyr 245 ALS inhibitors (B/2)
16Amaranthus retroflexusRedroot Pigweed5216
25 SpainSpain 1986 Corn (maize) atrazine 38 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed187
26 SwitzerlandSwitzerland 1982 Grapes, Orchards, and Vegetables simazine 41 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed199
27 United States (Indiana) United StatesIndiana1980 Cropland atrazine 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed408
28 United States (Colorado) United StatesColorado1982 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed430
29 United States (Connecticut) United StatesConnecticut1984 Corn (maize) atrazine, and cyanazine 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed1071
30 United States (New Hampshire) United StatesNew Hampshire1984 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed1078
31 United States (Maine) United StatesMaine1985 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed1092
32 United States (Minnesota) United StatesMinnesota1991 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed245
33 United States (Vermont) United StatesVermont1991 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed1101
34 United States (Virginia) United StatesVirginia1993 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed373
35 United States (Oregon) United StatesOregon1994 Mint terbacil 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed321
36 United States (Arkansas) United StatesArkansas1995 Cropland, and Soybean imazaquin 45 ALS inhibitors (B/2)
16Amaranthus retroflexusRedroot Pigweed402
37 United States (Kansas) United StatesKansas1995 Corn (maize), and Sorghum atrazine 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed1039
38 United States (Maryland) United StatesMaryland1998 Unspecified imazaquin, and imazethapyr 45 ALS inhibitors (B/2)
16Amaranthus retroflexusRedroot Pigweed1085
39 United States (Pennsylvania) United StatesPennsylvania1998 Corn (maize), Soybean, and Tomatoes atrazine, chlorimuron-ethyl, cloransulam-methyl, imazamox, imazaquin, imazethapyr, primisulfuron-methyl, and thifensulfuron-methyl 45 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed5021
40 United States (North Dakota) United StatesNorth Dakota1999 Soybean imazethapyr 45 ALS inhibitors (B/2)
16Amaranthus retroflexusRedroot Pigweed5046
41 United States (West Virginia) United StatesWest Virginia2000 Corn (maize) atrazine 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed7773
42 United States (Michigan) United StatesMichigan2001 Asparagus atrazine, and diuron 45 Multiple Resistance: 2 Sites of Action
Photosystem II inhibitors (C1/5)
PSII inhibitor (Ureas and amides) (C2/7)
16Amaranthus retroflexusRedroot Pigweed5177
43 United States (Idaho) United StatesIdaho2005 Potatoes metribuzin 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed5293
44 United States (Washington) United StatesWashington2010 Mint, and Potatoes metribuzin, and terbacil 45 Photosystem II inhibitors (C1/5)
16Amaranthus retroflexusRedroot Pigweed5667
45 United States (Mississippi) United StatesMississippi2010 Railways imazethapyr, pyrithiobac-sodium, and trifloxysulfuron-sodium 45 ALS inhibitors (B/2)
16Amaranthus retroflexusRedroot Pigweed16079
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