INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE
select
Weeds Resistant to Auxin Mimics HRAC Group 4 (Legacy O)
by species and country
Weeds Resistant to Auxin Mimics HRAC Group 4 (Legacy O)
by species and country
Drag a column header and drop it here to group by that column
Weeds Resistant to Auxin Mimics HRAC Group 4 (Legacy O)
by species and country
#SpeciesCountryFirst Year
1 Amaranthus hybridus (syn: quitensis)
Smooth Pigweed 		2016 - Argentina *Multiple - 2 SOA's
2016 - Argentina
201612Amaranthus hybridus (syn: quitensis)Smooth PigweedO244Auxin Mimics
2 Amaranthus palmeri
Palmer Amaranth 		2015 - United States (Kansas) *Multiple - 5 SOA's
2018 - United States (Kansas)
2020 - United States (Tennessee) *Multiple - 2 SOA's
2021 - United States (Kansas) *Multiple - 6 SOA's
2023 - United States (Arkansas)
2025 - United States (North Carolina) *Multiple - 5 SOA's
 		201514Amaranthus palmeriPalmer AmaranthO244Auxin Mimics
3 Amaranthus powellii
Powell Amaranth 		2019 - Canada (Ontario) *Multiple - 2 SOA's
 		201915Amaranthus powelliiPowell AmaranthO244Auxin Mimics
4 Amaranthus tuberculatus (=A. rudis)
Tall Waterhemp 		2009 - United States (Nebraska) *Multiple - 3 SOA's
2016 - United States (Illinois) *Multiple - 5 SOA's
2021 - United States (Iowa)
2009219Amaranthus tuberculatus (=A. rudis)Tall WaterhempO244Auxin Mimics
5 Ambrosia artemisiifolia
Common Ragweed 		2022 - United States (Michigan)
202218Ambrosia artemisiifoliaCommon RagweedO244Auxin Mimics
6 Arctotheca calendula
Capeweed 		2015 - Australia (South Australia)
201521Arctotheca calendulaCapeweedO244Auxin Mimics
7 Brassica rapa (=B. campestris)
Birdsrape Mustard 		2015 - Argentina
2021 - Mexico *Multiple - 3 SOA's
 		201536Brassica rapa (=B. campestris)Birdsrape MustardO244Auxin Mimics
8 Carduus acanthoides
Plumeless Thistle 		2019 - Argentina *Multiple - 2 SOA's
 		2019348Carduus acanthoidesPlumeless ThistleO244Auxin Mimics
9 Carduus nutans
Musk Thistle 		1981 - New Zealand
198142Carduus nutansMusk ThistleO244Auxin Mimics
10 Carduus pycnocephalus
Italian Thistle 		1997 - New Zealand
199743Carduus pycnocephalusItalian ThistleO244Auxin Mimics
11 Centaurea cyanus
Cornflower 		2012 - Poland
2012277Centaurea cyanusCornflowerO244Auxin Mimics
12 Centaurea solstitialis
Yellow Starthistle 		1988 - United States (Washington)
198844Centaurea solstitialisYellow StarthistleO244Auxin Mimics
13 Centaurea stoebe ssp. micranthos
Spotted knapweed 		2013 - Canada (British Columbia)
2013334Centaurea stoebe ssp. micranthosSpotted knapweedO244Auxin Mimics
14 Chenopodium album
Common Lambsquarters 		2005 - New Zealand
200547Chenopodium albumCommon LambsquartersO244Auxin Mimics
15 Cirsium arvense
Canada thistle 		1979 - Sweden
1985 - Hungary
197955Cirsium arvenseCanada thistleO244Auxin Mimics
16 Commelina diffusa
Spreading Dayflower 		1957 - United States (Hawaii)
195756Commelina diffusaSpreading DayflowerO244Auxin Mimics
17 Conyza sumatrensis
Sumatran Fleabane 		2017 - Brazil *Multiple - 5 SOA's
 		201765Conyza sumatrensisSumatran FleabaneO244Auxin Mimics
18 Daucus carota
Wild Carrot 		1957 - Canada (Ontario)
1993 - United States (Michigan)
1994 - United States (Ohio)
195776Daucus carotaWild CarrotO244Auxin Mimics
19 Descurainia sophia
Flixweed 		2011 - China
2011237Descurainia sophiaFlixweedO244Auxin Mimics
20 Digitaria ischaemum
Smooth Crabgrass 		2002 - United States (California)
2002177Digitaria ischaemumSmooth CrabgrassO244Auxin Mimics
21 Echinochloa colona
Junglerice 		2000 - Colombia
200078Echinochloa colonaJunglericeO244Auxin Mimics
22 Echinochloa crus-galli var. crus-galli
Barnyardgrass 		1998 - United States (Louisiana)
1999 - Brazil
1999 - United States (Arkansas) *Multiple - 2 SOA's
2000 - China
2009 - Brazil *Multiple - 2 SOA's
2013 - Uruguay
2018 - Brazil *Multiple - 3 SOA's
 		199879Echinochloa crus-galli var. crus-galliBarnyardgrassO244Auxin Mimics
23 Echinochloa crus-galli var. zelayensis
Gulf Cockspur Grass 		2013 - China
2013305Echinochloa crus-galli var. zelayensisGulf Cockspur GrassO244Auxin Mimics
24 Echinochloa crus-pavonis
Gulf Cockspur 		1999 - Brazil
2024 - China
1999193Echinochloa crus-pavonisGulf CockspurO244Auxin Mimics
25 Fimbristylis miliacea
Globe Fringerush 		1989 - Malaysia
198990Fimbristylis miliaceaGlobe FringerushO244Auxin Mimics
26 Galeopsis tetrahit
Common Hempnettle 		1998 - Canada (Alberta)
199891Galeopsis tetrahitCommon HempnettleO244Auxin Mimics
27 Galium aparine
Catchweed Bedstraw 		2014 - China
2016 - Iran
2017 - Iran *Multiple - 2 SOA's
 		2014272Galium aparineCatchweed BedstrawO244Auxin Mimics
28 Galium spurium
False Cleavers 		1996 - Canada (Alberta) *Multiple - 2 SOA's
 		199693Galium spuriumFalse CleaversO244Auxin Mimics
29 Hirschfeldia incana
Shortpod Mustard 		2016 - Argentina *Multiple - 2 SOA's
 		2016328Hirschfeldia incanaShortpod MustardO244Auxin Mimics
30 Kochia scoparia
Kochia 		1994 - United States (Montana)
1995 - United States (North Dakota)
1997 - United States (Idaho)
1999 - United States (Colorado)
2009 - United States (Nebraska)
2013 - United States (Kansas) *Multiple - 4 SOA's
2013 - United States (Kansas) *Multiple - 2 SOA's
2015 - Canada (Saskatchewan) *Multiple - 2 SOA's
2017 - Canada (Alberta) *Multiple - 3 SOA's
2022 - Spain *Multiple - 3 SOA's
 		1994101Kochia scopariaKochiaO244Auxin Mimics
31 Lactuca serriola
Prickly Lettuce 		2007 - United States (Washington)
2007102Lactuca serriolaPrickly LettuceO244Auxin Mimics
32 Limnocharis flava
Sawah Flowering Rush 		1995 - Indonesia
1998 - Malaysia *Multiple - 2 SOA's
 		1995104Limnocharis flavaSawah Flowering RushO244Auxin Mimics
33 Limnophila erecta
Marshweed 		2002 - Malaysia *Multiple - 2 SOA's
 		2002226Limnophila erectaMarshweedO244Auxin Mimics
34 Papaver rhoeas
Corn Poppy 		1993 - Spain *Multiple - 2 SOA's
1998 - Italy *Multiple - 2 SOA's
1998 - Italy
2002 - Greece *Multiple - 2 SOA's
2015 - France
2016 - France *Multiple - 2 SOA's
2018 - Portugal *Multiple - 2 SOA's
2025 - Morocco *Multiple - 2 SOA's
2025 - Tunisia *Multiple - 2 SOA's
 		1993123Papaver rhoeasCorn PoppyO244Auxin Mimics
35 Plantago lanceolata
Buckhorn Plantain 		2016 - United States (Indiana)
2016220Plantago lanceolataBuckhorn PlantainO244Auxin Mimics
36 Ranunculus acris
Tall Buttercup 		1988 - New Zealand
2010 - New Zealand *Multiple - 2 SOA's
 		1988140Ranunculus acrisTall ButtercupO244Auxin Mimics
37 Raphanus raphanistrum
Wild Radish 		1999 - Australia (Western Australia)
2006 - Australia (South Australia) *Multiple - 3 SOA's
2009 - Australia (Victoria) *Multiple - 2 SOA's
2010 - Australia (Western Australia) *Multiple - 4 SOA's
2011 - Australia (Victoria)
2013 - Australia (New South Wales )
2015 - Australia (Western Australia) *Multiple - 5 SOA's
2020 - Australia (Western Australia) *Multiple - 3 SOA's
 		1999141Raphanus raphanistrumWild RadishO244Auxin Mimics
38 Sagittaria montevidensis
California Arrowhead 		2023 - Brazil
2023146Sagittaria montevidensisCalifornia ArrowheadO244Auxin Mimics
39 Sinapis arvensis
Wild Mustard 		1990 - Canada (Manitoba)
2008 - Turkey *Multiple - 2 SOA's
 		1990158Sinapis arvensisWild MustardO244Auxin Mimics
40 Sisymbrium orientale
Oriental Mustard 		2005 - Australia (South Australia) *Multiple - 2 SOA's
 		2005159Sisymbrium orientaleOriental MustardO244Auxin Mimics
41 Soliva sessilis
Lawn Burweed 		1999 - New Zealand
1999199Soliva sessilisLawn BurweedO244Auxin Mimics
42 Sonchus oleraceus
Annual Sowthistle 		2015 - Australia (South Australia)
2015 - Australia (Victoria)
2015164Sonchus oleraceusAnnual SowthistleO244Auxin Mimics
43 Sphenoclea zeylanica
Gooseweed 		1983 - Philippines
1995 - Malaysia
2000 - Thailand
1983167Sphenoclea zeylanicaGooseweedO244Auxin Mimics
44 Stellaria media
Common Chickweed 		1985 - United Kingdom
2010 - China
1985168Stellaria mediaCommon ChickweedO244Auxin Mimics
HRAC Global Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Friday, September 25, 2026.  Available at  www.weedscience.org

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