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 3, 2020Conyza canadensisFranceFrance 201917 EPSP synthase inhibitors (G/9)
 		61Horseweed18198
2 June 22, 2020Eleusine indicaMexicoMexico 201629 EPSP synthase inhibitors (G/9)
 		81Goosegrass18194
3 June 22, 2020Chloris barbata = (C. inflate)MexicoMexico 201829 EPSP synthase inhibitors (G/9)
 		53Swollen Fingergrass18197
4 June 22, 2020Parthenium hysterophorusMexicoMexico 201729 EPSP synthase inhibitors (G/9)
 		124Ragweed Parthenium18196
5 June 22, 2020Amaranthus palmeriMexicoMexico 201629 EPSP synthase inhibitors (G/9)
 		14Palmer Amaranth18195
6 June 22, 2020Sorghum halepenseAustralia (Queensland) AustraliaQueensland20191 EPSP synthase inhibitors (G/9)
 		166Johnsongrass18193
7 June 22, 2020Hordeum murinum ssp. leporinumSpainSpain 201838 EPSP synthase inhibitors (G/9)
 		98Hare Barley18192
8 May 20, 2020Eleusine indicaUnited States (Alabama) United StatesAlabama201945 PSI Electron Diverter (D/22)
 		81Goosegrass18191
9 January 22, 2020Poa annuaAustralia (Victoria) AustraliaVictoria20171 ACCase inhibitors (A/1)
 		130Annual Bluegrass18190
10 January 22, 2020Poa annuaAustralia (New South Wales ) AustraliaNew South Wales 20171 ACCase inhibitors (A/1)
 		130Annual Bluegrass18189
11 January 22, 2020Avena fatuaAustralia (Queensland) AustraliaQueensland20181 EPSP synthase inhibitors (G/9)
 		28Wild Oat18187
12 November 28, 2019Amaranthus hybridus (syn: quitensis)BrazilBrazil 20185 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
 		12Smooth Pigweed18184
13 November 28, 2019Amaranthus palmeriUnited States (North Carolina) United StatesNorth Carolina201645 HPPD inhibitors (F2/27)
 		14Palmer Amaranth18188
14 November 28, 2019Secale cerealeUnited States (Colorado) United StatesColorado201845 ALS inhibitors (B/2)
 		351Feral Rye18182
15 November 28, 2019Echinochloa crus-galli var. crus-galliArgentinaArgentina 201948 EPSP synthase inhibitors (G/9)
 		79Barnyardgrass18183
16 November 22, 2019Avena sterilis ssp. ludovicianaAustralia (New South Wales ) AustraliaNew South Wales 20181 EPSP synthase inhibitors (G/9)
 		30Sterile oat18186
17 November 22, 2019Sonchus asperUnited KingdomUnited Kingdom 201644 ALS inhibitors (B/2)
 		163Spiny Sowthistle18185
18 November 19, 2019Rumex obtusifoliusFranceFrance 201717 ALS inhibitors (B/2)
 		349Broad-Leaved Dock18178
19 November 4, 2019Eleusine indicaColombiaColombia 201610 Multiple Resistance: 2 Sites of Action
PSI Electron Diverter (D/22)
EPSP synthase inhibitors (G/9)
 		81Goosegrass18177
20 October 24, 2019Capsella bursa-pastorisNorwayNorway 201931 ALS inhibitors (B/2)
 		41Shepherd's-purse18169
21 October 1, 2019Carduus acanthoidesArgentinaArgentina 201948 Multiple Resistance: 2 Sites of Action
EPSP synthase inhibitors (G/9)
Synthetic Auxins (O/4)
 		348Plumeless Thistle18173
22 September 28, 2019Echinochloa colonaColombiaColombia 201610 Multiple Resistance: 3 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
Cellulose inhibitors (L/26)
 		78Junglerice18163
23 September 25, 2019Urochloa panicoidesArgentinaArgentina 201748 EPSP synthase inhibitors (G/9)
 		171Liverseedgrass18158
24 September 24, 2019Oryza sativa var. sylvaticaColombiaColombia 201810 ALS inhibitors (B/2)
 		242Red Rice18170
25 September 2, 2019Rapistrum rugosumSpainSpain 201838 ALS inhibitors (B/2)
 		142Turnipweed18171
26 August 19, 2019Conyza sumatrensisTurkeyTurkey 201971 EPSP synthase inhibitors (G/9)
 		65Sumatran Fleabane18164
27 August 5, 2019Lithospermum arvenseChinaChina 20199 ALS inhibitors (B/2)
 		341Corn Gromwell18168
28 July 31, 2019Lolium perenne ssp. multiflorumUnited States (Oklahoma) United StatesOklahoma201745 ACCase inhibitors (A/1)
 		110Italian Ryegrass18167
29 July 31, 2019Chloris radiataColombiaColombia 201910 EPSP synthase inhibitors (G/9)
 		340Radiate Fingergrass18165
30 June 25, 2019Amaranthus palmeriUnited States (Arkansas) United StatesArkansas201645 Multiple Resistance: 5 Sites of Action
ALS inhibitors (B/2)
PPO inhibitors (E/14)
EPSP synthase inhibitors (G/9)
Microtubule inhibitors (K1/3)
Long chain fatty acid inhibitors (K3/15)
 		14Palmer Amaranth18156
31 June 25, 2019Conyza sumatrensisParaguayParaguay 201746 Multiple Resistance: 3 Sites of Action
ALS inhibitors (B/2)
PSI Electron Diverter (D/22)
EPSP synthase inhibitors (G/9)
 		65Sumatran Fleabane18153
32 May 15, 2019Amaranthus tuberculatus (=A. rudis)Canada (Ontario) CanadaOntario20177 Multiple Resistance: 2 Sites of Action
Photosystem II inhibitors (C1/5)
EPSP synthase inhibitors (G/9)
 		219Tall Waterhemp17142
33 May 13, 2019Galinsoga parvifloraFranceFrance 201817 ALS inhibitors (B/2)
 		339Gallant Soldier18162
34 May 13, 2019Conyza sumatrensisAustralia (Queensland) AustraliaQueensland20181 EPSP synthase inhibitors (G/9)
 		65Sumatran Fleabane18161
35 April 2, 2019Sorghum halepenseIsraelIsrael 201723 ALS inhibitors (B/2)
 		166Johnsongrass18159
36 March 1, 2019Amaranthus palmeriUnited States (Arkansas) United StatesArkansas201745 Long chain fatty acid inhibitors (K3/15)
 		14Palmer Amaranth18154
37 February 9, 2019Amaranthus tuberculatus (=A. rudis)United States (Illinois) United StatesIllinois201645 Long chain fatty acid inhibitors (K3/15)
 		219Tall Waterhemp18152
38 January 9, 2019Amaranthus palmeriUnited States (Kansas) United StatesKansas201845 Synthetic Auxins (O/4)
 		14Palmer Amaranth18151
39 December 31, 2018Ambrosia artemisiifoliaUnited States (Wisconsin) United StatesWisconsin201745 EPSP synthase inhibitors (G/9)
 		18Common Ragweed17155
40 December 15, 2018Lolium perenne ssp. multiflorumUnited States (Washington) United StatesWashington201845 Long chain fatty acid inhibitors (K3/15)
 		110Italian Ryegrass17154
41 December 15, 2018Lolium perenne ssp. multiflorumUnited KingdomUnited Kingdom 201844 Long chain fatty acid inhibitors (K3/15)
 		110Italian Ryegrass17153
42 December 15, 2018Lolium perenne ssp. multiflorumFranceFrance 201817 Long chain fatty acid inhibitors (K3/15)
 		110Italian Ryegrass17152
43 December 15, 2018Lolium perenne ssp. multiflorumUnited States (Oregon) United StatesOregon201845 Long chain fatty acid inhibitors (K3/15)
 		110Italian Ryegrass17151
44 November 9, 2018Bidens subalternansParaguayParaguay 201846 EPSP synthase inhibitors (G/9)
 		194Greater Beggarticks17150
45 October 10, 2018Conyza canadensisUnited States (Oklahoma) United StatesOklahoma201845 ALS inhibitors (B/2)
 		61Horseweed17149
46 October 2, 2018Conyza sumatrensisAustralia (Queensland) AustraliaQueensland20181 PSI Electron Diverter (D/22)
 		65Sumatran Fleabane17148
47 September 25, 2018Kochia scopariaCanada (Alberta) CanadaAlberta20177 Multiple Resistance: 3 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
Synthetic Auxins (O/4)
 		101Kochia17147
48 August 27, 2018Galium aparineIranIran 201779 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
Synthetic Auxins (O/4)
 		272Catchweed Bedstraw17138
49 August 16, 2018Amaranthus hybridus (syn: quitensis)ArgentinaArgentina 201648 Multiple Resistance: 2 Sites of Action
EPSP synthase inhibitors (G/9)
Synthetic Auxins (O/4)
 		12Smooth Pigweed17107
50 July 17, 2018Sorghum halepenseSerbiaSerbia 2017245 ACCase inhibitors (A/1)
 		166Johnsongrass17146
51 July 16, 2018Oryza sativa var. sylvaticaMalaysiaMalaysia 201828 ALS inhibitors (B/2)
 		242Red Rice17145
52 July 2, 2018Bromus catharticusArgentinaArgentina 201748 EPSP synthase inhibitors (G/9)
 		338Rescuegrass17144
53 June 26, 2018Bromus sterilisGermanyGermany 201718 ALS inhibitors (B/2)
 		289Poverty Brome17143
54 June 7, 2018Amaranthus tuberculatus (=A. rudis)Canada (Ontario) CanadaOntario20177 Multiple Resistance: 3 Sites of Action
ALS inhibitors (B/2)
Photosystem II inhibitors (C1/5)
EPSP synthase inhibitors (G/9)
 		219Tall Waterhemp17141
55 June 7, 2018Amaranthus tuberculatus (=A. rudis)Canada (Ontario) CanadaOntario20177 Multiple Resistance: 4 Sites of Action
ALS inhibitors (B/2)
Photosystem II inhibitors (C1/5)
PPO inhibitors (E/14)
EPSP synthase inhibitors (G/9)
 		219Tall Waterhemp17140
56 April 25, 2018Lolium rigidumGreeceGreece 201719 Glutamine synthase inhibitors (H/10)
 		112Rigid Ryegrass17136
57 April 25, 2018Lolium rigidumGreeceGreece 201619 EPSP synthase inhibitors (G/9)
 		112Rigid Ryegrass17137
58 April 13, 2018Conyza sumatrensisBrazilBrazil 20175 Multiple Resistance: 5 Sites of Action
PSII inhibitor (Ureas and amides) (C2/7)
PSI Electron Diverter (D/22)
PPO inhibitors (E/14)
EPSP synthase inhibitors (G/9)
Synthetic Auxins (O/4)
 		65Sumatran Fleabane17135
59 April 2, 2018Amaranthus palmeriUnited States (Oklahoma) United StatesOklahoma201845 EPSP synthase inhibitors (G/9)
 		14Palmer Amaranth17134
60 March 8, 2018Plantago lanceolataUnited States (Indiana) United StatesIndiana201645 Synthetic Auxins (O/4)
 		220Buckhorn Plantain17133
61 February 5, 2018Amaranthus tuberculatus (=A. rudis)United States (Nebraska) United StatesNebraska201645 Multiple Resistance: 4 Sites of Action
ALS inhibitors (B/2)
Photosystem II inhibitors (C1/5)
PPO inhibitors (E/14)
EPSP synthase inhibitors (G/9)
 		219Tall Waterhemp17121
62 January 28, 2018Brassica rapa (=B. campestris)Canada (Quebec) CanadaQuebec20177 EPSP synthase inhibitors (G/9)
 		36Birdsrape Mustard17130
63 December 30, 2017Hordeum murinum ssp. glaucumAustralia (South Australia) AustraliaSouth Australia20161 EPSP synthase inhibitors (G/9)
 		97Smooth Barley17118
64 December 8, 2017Eleusine indicaBrazilBrazil 20175 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
EPSP synthase inhibitors (G/9)
 		81Goosegrass17112
65 December 5, 2017Conyza sumatrensisFranceFrance 201617 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
 		65Sumatran Fleabane17115
66 December 5, 2017Conyza sumatrensisFranceFrance 201617 ALS inhibitors (B/2)
 		65Sumatran Fleabane17114
67 December 5, 2017Echinochloa crus-galli var. crus-galliUkraineUkraine 2017230 ALS inhibitors (B/2)
 		79Barnyardgrass17113
68 November 27, 2017Lactuca salignaAustralia (Western Australia) AustraliaWestern Australia20171 EPSP synthase inhibitors (G/9)
 		336Willow-leaved lettuce17111
69 November 9, 2017Ambrosia artemisiifoliaUnited States (New Jersey) United StatesNew Jersey201645 Multiple Resistance: 3 Sites of Action
ALS inhibitors (B/2)
PPO inhibitors (E/14)
EPSP synthase inhibitors (G/9)
 		18Common Ragweed17110
70 November 9, 2017Ambrosia artemisiifoliaUnited States (Maryland) United StatesMaryland201645 Multiple Resistance: 3 Sites of Action
ALS inhibitors (B/2)
PPO inhibitors (E/14)
EPSP synthase inhibitors (G/9)
 		18Common Ragweed17109
71 October 12, 2017Amaranthus hybridus (syn: quitensis)ArgentinaArgentina 201648 Synthetic Auxins (O/4)
 		12Smooth Pigweed17108
72 October 5, 2017Ambrosia artemisiifoliaUnited States (Michigan) United StatesMichigan201645 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
PPO inhibitors (E/14)
 		18Common Ragweed17106
73 September 27, 2017Lolium rigidumSpainSpain 201638 Multiple Resistance: 2 Sites of Action
PPO inhibitors (E/14)
EPSP synthase inhibitors (G/9)
 		112Rigid Ryegrass17105
74 September 27, 2017Lolium perenne ssp. multiflorumUnited States (California) United StatesCalifornia201645 Multiple Resistance: 4 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
PSI Electron Diverter (D/22)
EPSP synthase inhibitors (G/9)
 		110Italian Ryegrass17104
75 September 19, 2017Conyza sumatrensisBrazilBrazil 20175 Multiple Resistance: 3 Sites of Action
ALS inhibitors (B/2)
PSI Electron Diverter (D/22)
EPSP synthase inhibitors (G/9)
 		65Sumatran Fleabane17102
76 September 14, 2017Hirschfeldia incanaArgentinaArgentina 201648 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
Synthetic Auxins (O/4)
 		328Shortpod Mustard17103
77 August 6, 2017Conyza sumatrensisBrazilBrazil 20175 PPO inhibitors (E/14)
 		65Sumatran Fleabane17099
78 July 28, 2017Amaranthus tuberculatus (=A. rudis)United States (Wisconsin) United StatesWisconsin201645 Multiple Resistance: 2 Sites of Action
PPO inhibitors (E/14)
EPSP synthase inhibitors (G/9)
 		219Tall Waterhemp16100
79 July 13, 2017Poa annuaAustralia (New South Wales ) AustraliaNew South Wales 20171 Multiple Resistance: 5 Sites of Action
ALS inhibitors (B/2)
Photosystem II inhibitors (C1/5)
EPSP synthase inhibitors (G/9)
Microtubule inhibitors (K1/3)
Unknown (Z/27)
 		130Annual Bluegrass16098
80 July 13, 2017Poa annuaAustralia (New South Wales ) AustraliaNew South Wales 20171 Microtubule inhibitors (K1/3)
 		130Annual Bluegrass16097
81 July 13, 2017Poa annuaAustralia (New South Wales ) AustraliaNew South Wales 20171 Unknown (Z/27)
 		130Annual Bluegrass16096
82 July 13, 2017Poa annuaAustralia (New South Wales ) AustraliaNew South Wales 20171 EPSP synthase inhibitors (G/9)
 		130Annual Bluegrass16095
83 July 13, 2017Poa annuaAustralia (New South Wales ) AustraliaNew South Wales 20171 Photosystem II inhibitors (C1/5)
 		130Annual Bluegrass16094
84 July 13, 2017Poa annuaAustralia (New South Wales ) AustraliaNew South Wales 20171 ALS inhibitors (B/2)
 		130Annual Bluegrass16093
85 July 12, 2017Poa annuaAustralia (Victoria) AustraliaVictoria20171 Microtubule inhibitors (K1/3)
 		130Annual Bluegrass16092
86 July 12, 2017Poa annuaAustralia (Victoria) AustraliaVictoria20171 EPSP synthase inhibitors (G/9)
 		130Annual Bluegrass16091
87 July 12, 2017Poa annuaAustralia (Victoria) AustraliaVictoria20171 Photosystem II inhibitors (C1/5)
 		130Annual Bluegrass16090
88 July 12, 2017Poa annuaAustralia (Victoria) AustraliaVictoria20171 ALS inhibitors (B/2)
 		130Annual Bluegrass16089
89 July 12, 2017Poa annuaAustralia (South Australia) AustraliaSouth Australia20171 ALS inhibitors (B/2)
 		130Annual Bluegrass16088
90 July 12, 2017Poa annuaAustralia (South Australia) AustraliaSouth Australia20171 Microtubule inhibitors (K1/3)
 		130Annual Bluegrass16087
91 July 12, 2017Poa annuaAustralia (South Australia) AustraliaSouth Australia20171 Unknown (Z/27)
 		130Annual Bluegrass16086
92 July 12, 2017Poa annuaAustralia (South Australia) AustraliaSouth Australia20171 Photosystem II inhibitors (C1/5)
 		130Annual Bluegrass16085
93 July 12, 2017Poa annuaAustralia (South Australia) AustraliaSouth Australia20171 EPSP synthase inhibitors (G/9)
 		130Annual Bluegrass16084
94 June 28, 2017Conyza sumatrensisBrazilBrazil 20165 PSI Electron Diverter (D/22)
 		65Sumatran Fleabane16082
95 June 28, 2017Galium aparineIranIran 201679 Synthetic Auxins (O/4)
 		272Catchweed Bedstraw16083
96 May 16, 2017Amaranthus retroflexusChinaChina 20179 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
PPO inhibitors (E/14)
 		16Redroot Pigweed16078
97 May 12, 2017Conyza canadensisSouth KoreaSouth Korea 201727 EPSP synthase inhibitors (G/9)
 		61Horseweed16077
98 May 7, 2017Apera spica-ventiDenmarkDenmark 201613 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
 		20Silky Windgrass15078
99 May 7, 2017Lolium perenneDenmarkDenmark 201613 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
 		111Perennial Ryegrass15077

PERMISSION MUST BE OBTAINED FIRST if you intend to base a significant portion of a scientific paper on data derived from this site. Citation:
Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Monday, August 3, 2020 .  Available  www.weedscience.org Copyright © 1993- 2020 WeedScience.org All rights reserved. Fair use of this material is encouraged. Proper citation is requested.