International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
MULTIPLE RESISTANT PALMER AMARANTH
(Amaranthus palmeri)


Multiple Resistance: 4 Sites of Action
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2)
Inhibition of Hydroxyphenyl Pyruvate Dioxygenase HRAC Group 27 (Legacy F2)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)

United States, Iowa
INTRODUCTION PALMER AMARANTH
Palmer Amaranth (Amaranthus palmeri) is a dicot weed in the Amaranthaceae family.  In Iowa this weed first evolved multiple resistance (to 4 herbicide sites of action) in 2022 and infests Corn (maize), and Soybean.  Multiple resistance has evolved to herbicides in the Groups 2 (Legacy B), PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2), Inhibition of Hydroxyphenyl Pyruvate Dioxygenase HRAC Group 27 (Legacy F2), and Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G).  These particular biotypes are known to have resistance to atrazine, glyphosate, imazethapyr, and mesotrione and they may be cross-resistant to other herbicides in the Groups 2 (Legacy B), PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2), Inhibition of Hydroxyphenyl Pyruvate Dioxygenase HRAC Group 27 (Legacy F2), 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 Mar 18, 2024 )

Common NamePalmer Amaranth
SpeciesAmaranthus palmeri
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2)

Inhibition of Hydroxyphenyl Pyruvate Dioxygenase HRAC Group 27 (Legacy F2)

Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
Herbicidesatrazine, glyphosate, imazethapyr, and mesotrione
LocationUnited States, Iowa
Year2022
Situation(s)Corn (maize), and Soybean
Contributors - (Alphabetically)Robert Hartzler, and Micheal Owen 
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ACADEMIC ASPECTS

Confirmation Tests

Field, and Greenhouse trials comparing a known susceptible Palmer Amaranth biotype with this Palmer Amaranth 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, 5, 27, 9 resistant Palmer Amaranth 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 Palmer Amaranth from Iowa please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

ROBERT HARTZLER
Extension Weed Specialist and Professor of Agronomy
Iowa State University
Weed Science
2104 Agronomy Hall
Ames, 50011, Iowa
United States
Email Robert Hartzler
Web   : Web Site Link
MICHEAL OWEN
Associate Chair And Professor
Iowa State University
Agronomy Department
3218 Agronomy Hall
Ames, 50011, Iowa
United States
Email Micheal Owen
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Iowa have been instrumental in providing you this information. Particular thanks is given to Robert Hartzler, and Micheal Owen for providing detailed information.
Herbicide Resistant Palmer Amaranth Globally
(Amaranthus palmeri)
Herbicide Resistant Palmer Amaranth Globally
(Amaranthus palmeri)
Drag a column header and drop it here to group by that column
Herbicide Resistant Palmer Amaranth Globally
(Amaranthus palmeri)
#CountryFirstYearSituationActive IngredientsSite of Action
1 ArgentinaArgentina 2015 Soybean glyphosate 48 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth13038
2 BrazilBrazil 2015 Cotton glyphosate 5 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth11009
3 BrazilBrazil 2016 Corn (maize), Cotton, and Soybean chlorimuron-ethyl, cloransulam-methyl, glyphosate, and imazethapyr 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)
14Amaranthus palmeriPalmer Amaranth13042
4 IsraelIsrael 2008 Corn (maize), Cotton, and Watermelon foramsulfuron, iodosulfuron-methyl-Na, mesosulfuron-methyl, pyrithiobac-sodium, rimsulfuron, and trifloxysulfuron-Na 23 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
14Amaranthus palmeriPalmer Amaranth9921
5 MexicoMexico 2016 Cotton glyphosate 29 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth18195
6 South AfricaSouth Africa 2018 Cotton chlorimuron-ethyl, and glyphosate 37 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)
14Amaranthus palmeriPalmer Amaranth23244
7 SpainSpain 2016 Corn (maize), and Roadsides nicosulfuron 38 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
14Amaranthus palmeriPalmer Amaranth18204
8 SpainSpain 2023 Roadsides glyphosate, imazamox, and thifensulfuron-methyl 38 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)
14Amaranthus palmeriPalmer Amaranth27292
9 United States (South Carolina) United StatesSouth Carolina1989 Cotton, and Soybean trifluralin 45 Inhibition of Microtubule Assembly ( HRAC Group 3 (Legacy K1)
14Amaranthus palmeriPalmer Amaranth267
10 United States (Texas) United StatesTexas1993 Corn (maize), and Sorghum atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
14Amaranthus palmeriPalmer Amaranth270
11 United States (Kansas) United StatesKansas1993 Alfalfa, Corn (maize), Sorghum, and Soybean imazethapyr 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
14Amaranthus palmeriPalmer Amaranth332
12 United States (Arkansas) United StatesArkansas1994 Soybean chlorimuron-ethyl, diclosulam, imazaquin, imazethapyr, and pyrithiobac-sodium 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
14Amaranthus palmeriPalmer Amaranth403
13 United States (Tennessee) United StatesTennessee1994 Cotton, and Soybean imazaquin, and pyrithiobac-sodium 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
14Amaranthus palmeriPalmer Amaranth5313
14 United States (Kansas) United StatesKansas1995 Corn (maize), and Sorghum atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
14Amaranthus palmeriPalmer Amaranth1040
15 United States (North Carolina) United StatesNorth Carolina1995 Soybean chlorimuron-ethyl 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
14Amaranthus palmeriPalmer Amaranth1059
16 United States (South Carolina) United StatesSouth Carolina1997 Corn (maize), Cotton, Peanut (groundnut), and Soybean imazapic, imazaquin, and imazethapyr 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
14Amaranthus palmeriPalmer Amaranth1111
17 United States (Tennessee) United StatesTennessee1998 Cotton, and Soybean trifluralin 45 Inhibition of Microtubule Assembly ( HRAC Group 3 (Legacy K1)
14Amaranthus palmeriPalmer Amaranth5569
18 United States (Georgia) United StatesGeorgia2000 Peanut (groundnut) imazapic, and imazethapyr 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
14Amaranthus palmeriPalmer Amaranth5092
19 United States (Georgia) United StatesGeorgia2005 Cotton, and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5256
20 United States (North Carolina) United StatesNorth Carolina2005 Corn (maize), Cotton, and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5360
21 United States (Arkansas) United StatesArkansas2006 Cotton, and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5296
22 United States (Tennessee) United StatesTennessee2006 Corn (maize), Cotton, and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5387
23 United States (South Carolina) United StatesSouth Carolina2006 Cotton, and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth7780
24 United States (New Mexico) United StatesNew Mexico2007 Orchards, and Pecan nut glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5386
25 United States (Mississippi) United StatesMississippi2008 Cotton glyphosate, and pyrithiobac-sodium 45 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)
14Amaranthus palmeriPalmer Amaranth5359
26 United States (Florida) United StatesFlorida2008 Cropland imazapic, and pyrithiobac-sodium 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
14Amaranthus palmeriPalmer Amaranth5369
27 United States (Alabama) United StatesAlabama2008 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5388
28 United States (Missouri) United StatesMissouri2008 Corn (maize), Cotton, and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5391
29 United States (Georgia) United StatesGeorgia2008 Cotton glyphosate, and pyrithiobac-sodium 45 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)
14Amaranthus palmeriPalmer Amaranth5498
30 United States (Georgia) United StatesGeorgia2008 Corn (maize) atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
14Amaranthus palmeriPalmer Amaranth5499
31 United States (Tennessee) United StatesTennessee2009 Cotton, and Soybean chlorimuron-ethyl, glyphosate, and pyrithiobac-sodium 45 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)
14Amaranthus palmeriPalmer Amaranth5571
32 United States (Kansas) United StatesKansas2009 Corn (maize), and Sorghum atrazine, mesotrione, pyrasulfotole, tembotrione, thifensulfuron-methyl, and topramezone 45 Multiple Resistance: 3 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
Inhibition of Hydroxyphenyl Pyruvate Dioxygenase ( HRAC Group 27 (Legacy F2)
14Amaranthus palmeriPalmer Amaranth5705
33 United States (Louisiana) United StatesLouisiana2010 Cotton glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5494
34 United States (Illinois) United StatesIllinois2010 Corn (maize), and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5543
35 United States (Ohio) United StatesOhio2010 Corn (maize), and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5696
36 United States (South Carolina) United StatesSouth Carolina2010 Corn (maize), Cotton, and Soybean glyphosate, pyrithiobac-sodium, thifensulfuron-methyl, and trifloxysulfuron-Na 45 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)
14Amaranthus palmeriPalmer Amaranth7781
37 United States (Georgia) United StatesGeorgia2010 Corn (maize) atrazine, glyphosate, imazapic, and pyrithiobac-sodium 45 Multiple Resistance: 3 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth7788
38 United States (Kentucky) United StatesKentucky2010 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth7882
39 United States (Michigan) United StatesMichigan2011 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5557
40 United States (Virginia) United StatesVirginia2011 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5568
41 United States (Nebraska) United StatesNebraska2011 Corn (maize) atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
14Amaranthus palmeriPalmer Amaranth5694
42 United States (Nebraska) United StatesNebraska2011 Corn (maize) mesotrione, tembotrione, and topramezone 45 Inhibition of Hydroxyphenyl Pyruvate Dioxygenase ( HRAC Group 27 (Legacy F2)
14Amaranthus palmeriPalmer Amaranth5700
43 United States (Kansas) United StatesKansas2011 Cotton, and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5704
44 United States (Texas) United StatesTexas2011 Cotton glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth7777
45 United States (Arkansas) United StatesArkansas2011 Soybean fomesafen, pyrithiobac-sodium, and trifloxysulfuron-Na 45 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
14Amaranthus palmeriPalmer Amaranth11006
46 United States (Arizona) United StatesArizona2012 Cotton glyphosate, and pyrithiobac-sodium 45 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)
14Amaranthus palmeriPalmer Amaranth5699
47 United States (Delaware) United StatesDelaware2012 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth5707
48 United States (Indiana) United StatesIndiana2012 Corn (maize), and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth7835
49 United States (Pennsylvania) United StatesPennsylvania2013 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth7779
50 United States (Illinois) United StatesIllinois2013 Corn (maize), and Soybean imazethapyr, and primisulfuron-methyl 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
14Amaranthus palmeriPalmer Amaranth7866
51 United States (Illinois) United StatesIllinois2013 Corn (maize), and Soybean glyphosate, imazethapyr, and primisulfuron-methyl 45 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)
14Amaranthus palmeriPalmer Amaranth7867
52 United States (Florida) United StatesFlorida2013 Corn (maize), and Cotton glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth7869
53 United States (Florida) United StatesFlorida2013 Soybean glyphosate, and imazapic 45 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)
14Amaranthus palmeriPalmer Amaranth7870
54 United States (Wisconsin) United StatesWisconsin2013 Corn (maize), and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth10957
55 United States (Delaware) United StatesDelaware2014 Soybean chlorimuron-ethyl, and glyphosate 45 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)
14Amaranthus palmeriPalmer Amaranth8914
56 United States (Maryland) United StatesMaryland2014 Soybean chlorimuron-ethyl, and glyphosate 45 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)
14Amaranthus palmeriPalmer Amaranth8915
57 United States (New Jersey) United StatesNew Jersey2014 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth9922
58 United States (Nebraska) United StatesNebraska2014 Corn (maize) atrazine, mesotrione, tembotrione, and topramezone 45 Multiple Resistance: 2 Sites of Action
PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
Inhibition of Hydroxyphenyl Pyruvate Dioxygenase ( HRAC Group 27 (Legacy F2)
14Amaranthus palmeriPalmer Amaranth13048
59 United States (Wisconsin) United StatesWisconsin2014 Corn (maize) imazethapyr, tembotrione, and thifensulfuron-methyl 45 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Hydroxyphenyl Pyruvate Dioxygenase ( HRAC Group 27 (Legacy F2)
14Amaranthus palmeriPalmer Amaranth16099
60 United States (Tennessee) United StatesTennessee2015 Soybean fomesafen, and glyphosate 45 Multiple Resistance: 2 Sites of Action
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth13037
61 United States (California) United StatesCalifornia2015 Corn (maize) glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth13041
62 United States (Kansas) United StatesKansas2015 Sorghum 2,4-D, atrazine, chlorsulfuron, glyphosate, and mesotrione 45 Multiple Resistance: 5 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
Inhibition of Hydroxyphenyl Pyruvate Dioxygenase ( HRAC Group 27 (Legacy F2)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
Auxin Mimics ( HRAC Group 4 (Legacy O)
14Amaranthus palmeriPalmer Amaranth18157
63 United States (Nebraska) United StatesNebraska2016 Soybean atrazine, and glyphosate 45 Multiple Resistance: 2 Sites of Action
PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth13047
64 United States (Illinois) United StatesIllinois2016 Corn (maize), Horseradish, and Soybean fomesafen, glyphosate, and lactofen 45 Multiple Resistance: 2 Sites of Action
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth13050
65 United States (Arkansas) United StatesArkansas2016 Cotton, and Soybean acifluorfen, carfentrazone-ethyl, flumetsulam, fluthiacet-methyl, fomesafen, glyphosate, imazethapyr, lactofen, pendimethalin, pyraflufen-ethyl, pyrithiobac-sodium, S-metolachlor, and trifloxysulfuron-Na 45 Multiple Resistance: 5 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
Inhibition of Microtubule Assembly ( HRAC Group 3 (Legacy K1)
Very Long-Chain Fatty Acid Synthesis inhibitors ( HRAC Group 15 (Legacy K3 N)
14Amaranthus palmeriPalmer Amaranth18156
66 United States (North Carolina) United StatesNorth Carolina2016 Corn (maize) mesotrione 45 Inhibition of Hydroxyphenyl Pyruvate Dioxygenase ( HRAC Group 27 (Legacy F2)
14Amaranthus palmeriPalmer Amaranth18188
67 United States (Arkansas) United StatesArkansas2017 Soybean S-metolachlor 45 Very Long-Chain Fatty Acid Synthesis inhibitors ( HRAC Group 15 (Legacy K3 N)
14Amaranthus palmeriPalmer Amaranth18154
68 United States (Oklahoma) United StatesOklahoma2018 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth17134
69 United States (Kansas) United StatesKansas2018 Sorghum 2,4-D 45 Auxin Mimics ( HRAC Group 4 (Legacy O)
14Amaranthus palmeriPalmer Amaranth18151
70 United States (Connecticut) United StatesConnecticut2019 Pumpkin and squash chlorimuron-ethyl, glyphosate, halosulfuron-methyl, imazaquin, and sulfometuron-methyl 45 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)
14Amaranthus palmeriPalmer Amaranth18206
71 United States (Tennessee) United StatesTennessee2020 Cotton, and Soybean dicamba, and glyphosate 45 Multiple Resistance: 2 Sites of Action
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
Auxin Mimics ( HRAC Group 4 (Legacy O)
14Amaranthus palmeriPalmer Amaranth19221
72 United States (Arkansas) United StatesArkansas2020 Cotton glufosinate-ammonium 45 Inhibition of Glutamine Synthetase ( HRAC Group 10 (Legacy H)
14Amaranthus palmeriPalmer Amaranth20229
73 United States (Kansas) United StatesKansas2021 Sorghum 2,4-D, atrazine, chlorsulfuron, fomesafen, glyphosate, imazamox, imazethapyr, lactofen, mesotrione, metribuzin, pyrasulfotole, tembotrione, and thifensulfuron-methyl 45 Multiple Resistance: 6 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
Inhibition of Hydroxyphenyl Pyruvate Dioxygenase ( HRAC Group 27 (Legacy F2)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
Auxin Mimics ( HRAC Group 4 (Legacy O)
14Amaranthus palmeriPalmer Amaranth24257
74 United States (Colorado) United StatesColorado2021 Sugar beets glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth25265
75 United States (North Carolina) United StatesNorth Carolina2022 Corn (maize) atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
14Amaranthus palmeriPalmer Amaranth23241
76 United States (North Carolina) United StatesNorth Carolina2022 Cotton glufosinate-ammonium 45 Inhibition of Glutamine Synthetase ( HRAC Group 10 (Legacy H)
14Amaranthus palmeriPalmer Amaranth24244
77 United States (Iowa) United StatesIowa2022 Corn (maize), and Soybean atrazine, glyphosate, imazethapyr, and mesotrione 45 Multiple Resistance: 4 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
Inhibition of Hydroxyphenyl Pyruvate Dioxygenase ( HRAC Group 27 (Legacy F2)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth27284
78 United States (Idaho) United StatesIdaho2023 Cereals, Potatoes, Roadsides, Sugar beets, Wheat, and Winter barley glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth27265
79 UruguayUruguay 2022 Corn (maize), and Soybean glyphosate 73 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
14Amaranthus palmeriPalmer Amaranth24254
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