INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE
Most Recent Cases of Herbicide Resistant Weeds Entered into the Database
(click on a column header to sort or click on a country for details)
#Date Last UpdatedSpeciesCountryFirst YearSite of Action
1 July 25, 2025Lolium perenne ssp. multiflorumUnited States (New York) United StatesNew York202345 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		110Italian Ryegrass32273
2 July 24, 2025Kochia scopariaArgentinaArgentina 202348 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		101Kochia31277
3 July 24, 2025Daucus carotaNew ZealandNew Zealand 202530 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		76Wild Carrot32274
4 July 24, 2025Stellaria mediaEstoniaEstonia 202199 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		168Common Chickweed30270
5 July 24, 2025Amaranthus palmeriUnited States (North Carolina) United StatesNorth Carolina202545 Inhibition of Protoporphyrinogen Oxidase HRAC Group 14 (Legacy E)
 		14Palmer Amaranth32272
6 July 24, 2025Amaranthus palmeriUnited States (Missouri) United StatesMissouri202345 Auxin Mimics HRAC Group 4 (Legacy O)
 		14Palmer Amaranth32271
7 July 24, 2025Conyza sumatrensisArgentinaArgentina 201448 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		65Sumatran Fleabane32270
8 July 23, 2025Amaranthus tuberculatus (=A. rudis)ItalyItaly 201024 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		219Tall Waterhemp32269
9 July 23, 2025Amaranthus palmeriItalyItaly 201824 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		14Palmer Amaranth32268
10 June 5, 2025Poa trivialisIrelandIreland 202381 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		350Roughstalk Bluegrass31279
11 May 30, 2025Eleusine indicaArgentinaArgentina 201448 Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
 		81Goosegrass31278
12 May 30, 2025Panicum dichotomiflorumSpainSpain 202238 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		122Fall Panicum31276
13 May 30, 2025Kochia scopariaSpainSpain 202238 Multiple Resistance: 3 Sites of Action
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
Auxin Mimics HRAC Group 4 (Legacy O)
 		101Kochia31275
14 May 30, 2025Conyza sumatrensisBoliviaBolivia 20244 PS I Electron Diversion HRAC Group 22 (Legacy D)
 		65Sumatran Fleabane31271
15 May 30, 2025Rapistrum rugosumArgentinaArgentina 201848 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		142Turnipweed31273
16 May 22, 2025Amaranthus palmeriArgentinaArgentina 202548 Inhibition of Protoporphyrinogen Oxidase HRAC Group 14 (Legacy E)
 		14Palmer Amaranth31274
17 May 12, 2025Lolium rigidumSpainSpain 201538 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		112Rigid Ryegrass31272
18 April 24, 2025Conyza canadensisMexicoMexico 201829 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		61Horseweed31270
19 March 3, 2025Polygonum convolvulus (=Fallopia convolvulus)United States (Kansas) United StatesKansas202045 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		88Wild Buckwheat31269
20 February 24, 2025Brassica rapa (=B. campestris)MexicoMexico 202129 Multiple Resistance: 3 Sites of Action
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
Auxin Mimics HRAC Group 4 (Legacy O)
 		36Birdsrape Mustard31268
21 January 27, 2025Amaranthus palmeriUnited States (New York) United StatesNew York202445 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)
 		14Palmer Amaranth30269
22 January 27, 2025Conyza canadensisUnited States (New York) United StatesNew York202445 PS I Electron Diversion HRAC Group 22 (Legacy D)
 		61Horseweed30268
23 December 7, 2024Amaranthus palmeriTurkeyTurkey 202371 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)
 		14Palmer Amaranth29268
24 December 5, 2024Steinchisma laxumColombiaColombia 202310 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		1358Lax Panicgrass27271
25 December 2, 2024Setaria viridisUkraineUkraine 2024230 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		153Green Foxtail29269
26 November 27, 2024Alopecurus myosuroidesFranceFrance 202217 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		6Blackgrass29265
27 November 6, 2024Lolium rigidumTunisiaTunisia 202378 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		112Rigid Ryegrass29275
28 November 6, 2024Lolium rigidumAlgeriaAlgeria 2023115 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		112Rigid Ryegrass29277
29 November 6, 2024Lolium rigidumTunisiaTunisia 202378 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		112Rigid Ryegrass29276
30 October 24, 2024Atriplex patulaFranceFrance 201917 PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2)
 		26Halberdleaf Orach29266
31 October 10, 2024Lolium rigidumAlgeriaAlgeria 2023115 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		112Rigid Ryegrass29274
32 October 10, 2024Lolium rigidumAlgeriaAlgeria 2023115 Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
 		112Rigid Ryegrass29273
33 October 9, 2024Galium spuriumAustriaAustria 20242 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		93False Cleavers29264
34 September 28, 2024Lolium rigidumMoroccoMorocco 2023166 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		112Rigid Ryegrass29272
35 September 28, 2024Lolium rigidumMoroccoMorocco 2023166 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		112Rigid Ryegrass29278
36 September 28, 2024Lolium rigidumMoroccoMorocco 2023166 Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
 		112Rigid Ryegrass29271
37 September 23, 2024Echinochloa colonaPakistanPakistan 202486 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		78Junglerice29279
38 September 17, 2024Amaranthus albusIsraelIsrael 202323 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		7Tumble Pigweed29280
39 September 5, 2024Avena fatuaPakistanPakistan 202486 Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
 		28Wild Oat29281
40 August 24, 2024Alopecurus myosuroidesFranceFrance 202017 Very Long-Chain Fatty Acid Synthesis inhibitorsHRAC Group 15 (Legacy K3 N)
 		6Blackgrass29267
41 August 11, 2024Schoenoplectus juncoidesChinaChina 20249 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		196Rock Bulrush29282
42 August 6, 2024Echinochloa crus-pavonisChinaChina 20249 Auxin Mimics HRAC Group 4 (Legacy O)
 		193Gulf Cockspur29283
43 August 3, 2024Amaranthus palmeriUnited States (Oregon) United StatesOregon202345 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		14Palmer Amaranth29270
44 July 21, 2024Chenopodium albumCanada (New Brunswick) CanadaNew Brunswick20187 PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2)
 		47Common Lambsquarters28276
45 July 14, 2024Ambrosia artemisiifoliaCanada (Prince Edward Island) CanadaPrince Edward Island20237 PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2)
 		18Common Ragweed28275
46 July 12, 2024Amaranthus retroflexusCanada (Prince Edward Island) CanadaPrince Edward Island20237 PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2)
 		16Redroot Pigweed28274
47 July 8, 2024Chenopodium albumCanada (Prince Edward Island) CanadaPrince Edward Island20187 PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2)
 		47Common Lambsquarters28273
48 June 15, 2024Oryza sativa var. sylvaticaArgentinaArgentina 201848 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		242Red Rice27289
49 June 8, 2024Conyza bonariensisUruguayUruguay 202273 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)
 		60Hairy Fleabane27291
50 June 6, 2024Cyperus difformisPortugalPortugal 202334 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
PSII inhibitors - Histidine 215 Binders HRAC Group 6 (Legacy C3)
 		71Smallflower Umbrella Sedge28270
51 May 24, 2024Bidens pilosaBrazilBrazil 20225 Inhibition of Protoporphyrinogen Oxidase HRAC Group 14 (Legacy E)
 		32Hairy Beggarticks27288
52 May 24, 2024Digitaria sanguinalisSwitzerlandSwitzerland 202141 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		77Large Crabgrass27290
53 May 24, 2024Amaranthus hybridus (syn: quitensis)South AfricaSouth Africa 202437 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		12Smooth Pigweed27287
54 May 19, 2024Glebionis segetumGreeceGreece 202119 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		2358Corn Marigold28272
55 May 4, 2024Echinochloa phyllopogon (=E. oryzicola)PortugalPortugal 202034 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		178Late Watergrass28269
56 April 20, 2024Echinochloa phyllopogon (=E. oryzicola)PortugalPortugal 202034 Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
 		178Late Watergrass28268
57 April 9, 2024Papaver rhoeasPortugalPortugal 201834 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Auxin Mimics HRAC Group 4 (Legacy O)
 		123Corn Poppy28267
58 March 25, 2024Chloris truncataSpainSpain 202338 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		262Windmill Grass27293
59 March 18, 2024Conyza canadensisUnited States (Oregon) United StatesOregon202345 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		61Horseweed27286
60 March 18, 2024Conyza bonariensisUnited States (Oregon) United StatesOregon202345 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		60Hairy Fleabane27285
61 March 18, 2024Amaranthus palmeriUnited States (Iowa) United StatesIowa202245 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)
 		14Palmer Amaranth27284
62 March 5, 2024Papaver rhoeasPortugalPortugal 201834 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		123Corn Poppy28271
63 March 3, 2024Lolium perenne ssp. multiflorumPortugalPortugal 201934 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		110Italian Ryegrass28266
64 February 24, 2024Echinochloa crus-galli var. crus-galliPortugalPortugal 201834 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		79Barnyardgrass28265
65 February 20, 2024Echinochloa crus-galli var. crus-galliPortugalPortugal 201534 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		79Barnyardgrass28264
66 February 20, 2024Amaranthus palmeriSpainSpain 202338 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)
 		14Palmer Amaranth27292
67 February 18, 2024Echinochloa phyllopogon (=E. oryzicola)PortugalPortugal 201534 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		178Late Watergrass27294
68 January 21, 2024Bromus diandrusNew ZealandNew Zealand 202430 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		197Ripgut Brome27283
69 November 19, 2023Avena sterilisSpainSpain 202338 Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
 		29Sterile Oat27282
70 November 9, 2023Amaranthus tuberculatus (=A. rudis)United States (Idaho) United StatesIdaho202345 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		219Tall Waterhemp27264
71 November 3, 2023Amaranthus hybridus (syn: quitensis)ItalyItaly 201824 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		12Smooth Pigweed27281
72 October 30, 2023Amaranthus tuberculatus (=A. rudis)United States (Iowa) United StatesIowa202145 Auxin Mimics HRAC Group 4 (Legacy O)
 		219Tall Waterhemp27263
73 October 26, 2023Conyza bonariensisJordanJordan 202255 Multiple Resistance: 2 Sites of Action
PS I Electron Diversion HRAC Group 22 (Legacy D)
Inhibition of Protoporphyrinogen Oxidase HRAC Group 14 (Legacy E)
 		60Hairy Fleabane27269
74 October 25, 2023Echinochloa crus-galli var. crus-galliThailandThailand 202147 Inhibition of Cellulose Synthesis HRAC Group 29 (Legacy L)
 		79Barnyardgrass27275
75 October 18, 2023Poa annuaIrelandIreland 202181 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		130Annual Bluegrass27262
76 September 26, 2023Monochoria vaginalisIndonesiaIndonesia 202222 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		202Arrowleafed Monochoria27274
77 September 14, 2023Ambrosia artemisiifoliaUkraineUkraine 2023230 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Inhibition of Protoporphyrinogen Oxidase HRAC Group 14 (Legacy E)
 		18Common Ragweed26266
78 September 5, 2023Echinochloa crus-galli var. crus-galliBrazilBrazil 20185 Multiple Resistance: 3 Sites of Action
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Inhibition of Cellulose Synthesis HRAC Group 29 (Legacy L)
Auxin Mimics HRAC Group 4 (Legacy O)
 		79Barnyardgrass26265
79 September 5, 2023Bidens subalternansBrazilBrazil 20235 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		194Greater Beggarticks26263
80 September 5, 2023Sagittaria montevidensisBrazilBrazil 20235 Auxin Mimics HRAC Group 4 (Legacy O)
 		146California Arrowhead26264
81 August 28, 2023Bromus diandrusAustralia (Western Australia) AustraliaWestern Australia20201 Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
 		197Ripgut Brome26262
82 August 5, 2023Panicum miliaceum var. ruderale Kitag.ChinaChina 20239 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		1359Wild Panicgrass27273
83 July 13, 2023Echinochloa crus-galli var. crus-galliIndiaIndia 201721 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		79Barnyardgrass25264
84 July 11, 2023Amaranthus palmeriUnited States (Colorado) United StatesColorado202145 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		14Palmer Amaranth25265
85 July 6, 2023Digitaria sanguinalisNew ZealandNew Zealand 202230 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		77Large Crabgrass25262
86 June 29, 2023Hordeum jubatumCanada (Alberta) CanadaAlberta20227 Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
 		358Foxtail Barley25263
87 June 23, 2023Ammannia multifloraChinaChina 20229 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		1360Many Flowered Ammannia27279
88 June 8, 2023Galium spuriumGreeceGreece 202219 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		93False Cleavers27278
89 June 5, 2023Plantago lanceolataSouth AfricaSouth Africa 202237 Multiple Resistance: 2 Sites of Action
PS I Electron Diversion HRAC Group 22 (Legacy D)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		220Buckhorn Plantain27276
90 June 3, 2023Ambrosia artemisiifoliaUnited States (Michigan) United StatesMichigan202245 Auxin Mimics HRAC Group 4 (Legacy O)
 		18Common Ragweed27277
91 May 9, 2023Echinochloa oryzoidesArgentinaArgentina 201648 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		261Early Watergrass25261
92 May 9, 2023Poa annuaUnited States (Georgia) United StatesGeorgia202245 Inhibition of Cellulose Synthesis HRAC Group 29 (Legacy L)
 		130Annual Bluegrass25260
93 April 25, 2023Kochia scopariaCanada (Saskatchewan) CanadaSaskatchewan20217 Inhibition of Protoporphyrinogen Oxidase HRAC Group 14 (Legacy E)
 		101Kochia25259
94 April 24, 2023Bromus commutatusUnited KingdomUnited Kingdom 202044 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		357Meadow Brome25258
95 April 4, 2023Lolium perenne ssp. multiflorumChinaChina 20229 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		110Italian Ryegrass27266
96 March 30, 2023Digitaria ciliarisChinaChina 20219 Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
 		225Southern Crabgrass27272
97 March 12, 2023Echinochloa phyllopogon (=E. oryzicola)ChinaChina 20239 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		178Late Watergrass27267
98 March 11, 2023Ammannia auriculataChinaChina 20239 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		183Eared Redstem27280
99 February 2, 2023Leptochloa chinensisChinaChina 20239 Inhibition of Hydroxyphenyl Pyruvate Dioxygenase HRAC Group 27 (Legacy F2)
 		223Chinese Sprangletop27268
100 April 9, 2022Amaranthus palmeriUnited States (Idaho) United StatesIdaho202345 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		14Palmer Amaranth27265
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