International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
GROUP B/2 RESISTANT RIGID RYEGRASS
(Lolium rigidum)


Inhibition of Acetolactate Synthase (B/2)

Morocco
INTRODUCTION RIGID RYEGRASS
Rigid Ryegrass (Lolium rigidum) is a monocot weed in the Poaceae family.  In Morocco this weed first evolved resistance to Group B/2 herbicides in 2023 and infests Wheat.   Group B/2 herbicides are known as Inhibition of Acetolactate Synthase (Inhibition of Acetolactate Synthase ).  Research has shown that these particular biotypes are resistant to iodosulfuron-methyl-Na, mesosulfuron-methyl, and pyroxsulam 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 Sep 28, 2024 )

Common NameRigid Ryegrass
SpeciesLolium rigidum
GroupInhibition of Acetolactate Synthase (B/2)
Herbicidesiodosulfuron-methyl-Na, mesosulfuron-methyl, and pyroxsulam
LocationMorocco
Year2023
Situation(s)Wheat
Contributors - (Alphabetically)Katerina Hamouzova, Pavlína Košnarová, and Josef Soukup 
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Rigid Ryegrass biotype with this Rigid Ryegrass 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 Rigid Ryegrass 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

Studies on the mechanism of resistance of Group B/2 resistant Rigid Ryegrass from Morocco indicate that resistance is due to an altered target site.  There may be a note below or an article discussing the mechanism of resistance in the Fact Sheets and Other Literature
 
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 Rigid Ryegrass from Morocco please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

KATERINA HAMOUZOVA
Weed Research Scientist
Czech University Of Agriculture In Prague
Depart. Of Agroecology And Biometeorology
Kamycka 129
Prague, 6 - Suchdol, 16521, Prague
Czech Republic
Email Katerina Hamouzova
Web   : Web Site Link
PAVLÍNA KOŠNAROVÁ
Researcher
Czech University of Life Sciences
Agroecology and Plant Production
Kamycka 129
Prague , 16500, Czech Republic
Czech Republic
Email Pavlína Košnarová
Web   : Web Site Link
JOSEF SOUKUP
Professor
Czech University of Life Sciences Prague
Agroecology and Biometeorology
Kamycka 129
Prague 6 - Suchdol, 16521, Czech Republic
Czech Republic
Email Josef Soukup
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Morocco have been instrumental in providing you this information. Particular thanks is given to Katerina Hamouzova, Pavlína Košnarová, and Josef Soukup for providing detailed information.
Herbicide Resistant Rigid Ryegrass Globally
(Lolium rigidum)
Herbicide Resistant Rigid Ryegrass Globally
(Lolium rigidum)
Drag a column header and drop it here to group by that column
Herbicide Resistant Rigid Ryegrass Globally
(Lolium rigidum)
#CountryFirstYearSituationActive IngredientsSite of Action
1 AlgeriaAlgeria 2023 Wheat clodinafop-propargyl, and pinoxaden 115 Inhibition of Acetyl CoA Carboxylase (A/1)
112Lolium rigidumRigid Ryegrass29273
2 AlgeriaAlgeria 2023 Wheat iodosulfuron-methyl-Na, mesosulfuron-methyl, and pyroxsulam 115 Inhibition of Acetolactate Synthase (B/2)
112Lolium rigidumRigid Ryegrass29274
3 AlgeriaAlgeria 2023 Wheat clodinafop-propargyl, iodosulfuron-methyl-Na, mesosulfuron-methyl, pinoxaden, and pyroxsulam 115 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
112Lolium rigidumRigid Ryegrass29277
4 Australia (Western Australia) AustraliaWestern Australia1982 Canola, Spring Barley, and Wheat chlorsulfuron, diclofop-methyl, fluazifop-butyl, sethoxydim, tralkoxydim, and trifluralin 1 Multiple Resistance: 3 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
Inhibition of Microtubule Assembly (K1/3)
112Lolium rigidumRigid Ryegrass15
5 Australia (South Australia) AustraliaSouth Australia1982 Spring Barley, and Wheat chlorpropham, chlorsulfuron, clomazone, diclofop-methyl, ethalfluralin, fluazifop-butyl, imazapyr, metolachlor, metsulfuron-methyl, quizalofop-ethyl, sethoxydim, tralkoxydim, tri-allate, triasulfuron, and trifluralin 1 Multiple Resistance: 6 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
Inhibition of Deoxy-D-Xylulose Phosphate Synthase (F4/13)
Inhibition of Microtubule Assembly (K1/3)
Inhibition of Microtubule Organization (K2/23)
Very Long-Chain Fatty Acid Synthesis inhibitors (K3 N/15)
112Lolium rigidumRigid Ryegrass389
6 Australia (Western Australia) AustraliaWestern Australia1984 Cropland, Spring Barley, and Wheat chlorsulfuron, and metsulfuron-methyl 1 Inhibition of Acetolactate Synthase (B/2)
112Lolium rigidumRigid Ryegrass324
7 Australia (Western Australia) AustraliaWestern Australia1984 Cropland, and Pasture seed trifluralin 1 Inhibition of Microtubule Assembly (K1/3)
112Lolium rigidumRigid Ryegrass330
8 Australia (South Australia) AustraliaSouth Australia1984 Cropland metolachlor 1 Very Long-Chain Fatty Acid Synthesis inhibitors (K3 N/15)
112Lolium rigidumRigid Ryegrass398
9 Australia (Victoria) AustraliaVictoria1984 Pastures, Spring Barley, and Wheat chlorsulfuron, diclofop-methyl, fluazifop-butyl, metsulfuron-methyl, quizalofop-ethyl, sethoxydim, and trifluralin 1 Multiple Resistance: 3 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
Inhibition of Microtubule Assembly (K1/3)
112Lolium rigidumRigid Ryegrass5042
10 Australia (New South Wales ) AustraliaNew South Wales 1985 Canola, Chickpea, Faba beans, Lentils, Lupins, Peas, Spring Barley, and Wheat chlorsulfuron, diclofop-methyl, fluazifop-butyl, haloxyfop-methyl, metsulfuron-methyl, quizalofop-ethyl, sethoxydim, tralkoxydim, triasulfuron, and trifluralin 1 Multiple Resistance: 3 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
Inhibition of Microtubule Assembly (K1/3)
112Lolium rigidumRigid Ryegrass4
11 Australia (Western Australia) AustraliaWestern Australia1988 Railways, and Roadsides amitrole 1 Inhibition of Lycopene Cyclase (F3/11)
112Lolium rigidumRigid Ryegrass316
12 Australia (Western Australia) AustraliaWestern Australia1988 Cropland, Pasture seed, Railways, Roadsides, and Triazine-tolerant canola atrazine, and simazine 1 PSII inhibitors - Serine 264 Binders (C1 C2/5)
112Lolium rigidumRigid Ryegrass480
13 Australia (South Australia) AustraliaSouth Australia1994 Cereals trifluralin 1 Inhibition of Microtubule Assembly (K1/3)
112Lolium rigidumRigid Ryegrass5226
14 Australia (Victoria) AustraliaVictoria1996 Canola, Cereals, Fencelines, and Wheat glyphosate 1 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass380
15 Australia (New South Wales ) AustraliaNew South Wales 1997 Apples, Around Buildings, Canola, Cereals, Fencelines, Irrigation Channels, Roadsides, and Wheat glyphosate 1 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass5094
16 Australia (South Australia) AustraliaSouth Australia1999 Alfalfa, Cereals, Clover, Fencelines, Grapes, Irrigation Channels, and Roadsides glyphosate 1 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass5188
17 Australia (Victoria) AustraliaVictoria1999 Wheat chlorsulfuron, diclofop-methyl, glyphosate, and trifluralin 1 Multiple Resistance: 4 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
Inhibition of Microtubule Assembly (K1/3)
112Lolium rigidumRigid Ryegrass5363
18 Australia (Western Australia) AustraliaWestern Australia2003 Cereals, Fencelines, Grapes, Railways, and Roadsides glyphosate 1 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass5325
19 Australia (South Australia) AustraliaSouth Australia2008 Grapes amitrole, and glyphosate 1 Multiple Resistance: 2 Sites of Action
Inhibition of Lycopene Cyclase (F3/11)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass5515
20 Australia (South Australia) AustraliaSouth Australia2010 Pasture seed clethodim, and paraquat 1 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
PS I Electron Diversion (D/22)
112Lolium rigidumRigid Ryegrass5489
21 Australia (South Australia) AustraliaSouth Australia2010 Pasture seed atrazine, chlorsulfuron, clethodim, glyphosate, haloxyfop-methyl, imazapyr, iodosulfuron-methyl-Na, and paraquat 1 Multiple Resistance: 5 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
PSII inhibitors - Serine 264 Binders (C1 C2/5)
PS I Electron Diversion (D/22)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass5510
22 Australia (Western Australia) AustraliaWestern Australia2013 Grapes glyphosate, and paraquat 1 Multiple Resistance: 2 Sites of Action
PS I Electron Diversion (D/22)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass6754
23 Australia (Victoria) AustraliaVictoria2015 Wheat tri-allate 1 Very Long-Chain Fatty Acid Synthesis inhibitors (K3 N/15)
112Lolium rigidumRigid Ryegrass11023
24 Australia (New South Wales ) AustraliaNew South Wales 2015 Wheat tri-allate 1 Very Long-Chain Fatty Acid Synthesis inhibitors (K3 N/15)
112Lolium rigidumRigid Ryegrass11031
25 ChileChile 1997 Canola, Cereals, Lupins, Spring wheat, and Winter wheat clethodim, clodinafop-propargyl, diclofop-methyl, haloxyfop-methyl, sethoxydim, and tralkoxydim 8 Inhibition of Acetyl CoA Carboxylase (A/1)
112Lolium rigidumRigid Ryegrass5102
26 ChileChile 2003 Wheat clethodim, clodinafop-propargyl, diclofop-methyl, flucarbazone-Na, haloxyfop-methyl, iodosulfuron-methyl-Na, pinoxaden, and tepraloxydim 8 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
112Lolium rigidumRigid Ryegrass5427
27 FranceFrance 1993 Wheat diclofop-methyl 17 Inhibition of Acetyl CoA Carboxylase (A/1)
112Lolium rigidumRigid Ryegrass550
28 FranceFrance 2005 Cereals, Grapes, Orchards, and Rapeseed glyphosate 17 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass5285
29 FranceFrance 2006 Wheat flupyrsulfuron-methyl-Na, iodosulfuron-methyl-Na, mesosulfuron-methyl, and propoxycarbazone-Na 17 Inhibition of Acetolactate Synthase (B/2)
112Lolium rigidumRigid Ryegrass5330
30 GreeceGreece 1997 Winter wheat diclofop-methyl 19 Inhibition of Acetyl CoA Carboxylase (A/1)
112Lolium rigidumRigid Ryegrass553
31 GreeceGreece 2009 Winter wheat chlorsulfuron 19 Inhibition of Acetolactate Synthase (B/2)
112Lolium rigidumRigid Ryegrass13053
32 GreeceGreece 2016 Orchards glyphosate 19 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass17137
33 GreeceGreece 2017 Grapes, Olive, and Orchards glufosinate-ammonium 19 Inhibition of Glutamine Synthetase (H/10)
112Lolium rigidumRigid Ryegrass17136
34 IranIran 2007 Winter wheat clodinafop-propargyl, diclofop-methyl, and pinoxaden 79 Inhibition of Acetyl CoA Carboxylase (A/1)
112Lolium rigidumRigid Ryegrass5340
35 IsraelIsrael 1979 Orchards, and Roadsides atrazine, and simazine 23 PSII inhibitors - Serine 264 Binders (C1 C2/5)
112Lolium rigidumRigid Ryegrass97
36 IsraelIsrael 1998 Alfalfa, and Wheat clodinafop-propargyl, diclofop-methyl, pinoxaden, and quizalofop-ethyl 23 Inhibition of Acetyl CoA Carboxylase (A/1)
112Lolium rigidumRigid Ryegrass5109
37 IsraelIsrael 2007 Wheat chlorsulfuron, clodinafop-propargyl, florasulam, flumetsulam, glyphosate, imazapyr, iodosulfuron-methyl-Na, mesosulfuron-methyl, metosulam, pinoxaden, propoxycarbazone-Na, sulfometuron-methyl, and tribenuron-methyl 23 Multiple Resistance: 3 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass5556
38 IsraelIsrael 2013 Carrots, and Wheat clethodim, clodinafop-propargyl, cycloxydim, haloxyfop-methyl, iodosulfuron-methyl-Na, mesosulfuron-methyl, pinoxaden, propoxycarbazone-Na, and sulfometuron-methyl 23 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
112Lolium rigidumRigid Ryegrass10992
39 ItalyItaly 2007 Grapes, and Orchards glyphosate 24 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass5370
40 MoroccoMorocco 2023 Wheat clodinafop-propargyl, and pinoxaden 166 Inhibition of Acetyl CoA Carboxylase (A/1)
112Lolium rigidumRigid Ryegrass29271
41 MoroccoMorocco 2023 Wheat iodosulfuron-methyl-Na, mesosulfuron-methyl, and pyroxsulam 166 Inhibition of Acetolactate Synthase (B/2)
112Lolium rigidumRigid Ryegrass29272
42 MoroccoMorocco 2023 Wheat clodinafop-propargyl, iodosulfuron-methyl-Na, mesosulfuron-methyl, pinoxaden, and pyroxsulam 166 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
112Lolium rigidumRigid Ryegrass29278
43 Saudi ArabiaSaudi Arabia 1992 Cereals, and Wheat clodinafop-propargyl, diclofop-methyl, and tralkoxydim 35 Inhibition of Acetyl CoA Carboxylase (A/1)
112Lolium rigidumRigid Ryegrass551
44 South AfricaSouth Africa 1993 Wheat clodinafop-propargyl, diclofop-methyl, fluazifop-butyl, haloxyfop-methyl, imazamox, sethoxydim, and tralkoxydim 37 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
112Lolium rigidumRigid Ryegrass192
45 South AfricaSouth Africa 2001 Grapes glyphosate 37 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass5093
46 South AfricaSouth Africa 2002 Fruit, and Grapes paraquat 37 PS I Electron Diversion (D/22)
112Lolium rigidumRigid Ryegrass5119
47 South AfricaSouth Africa 2003 Grapes glyphosate, haloxyfop-methyl, paraquat, and tepraloxydim 37 Multiple Resistance: 3 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
PS I Electron Diversion (D/22)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass5239
48 SpainSpain 1992 Wheat chlorotoluron, and diclofop-methyl 38 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
PSII inhibitors - Serine 264 Binders (C1 C2/5)
112Lolium rigidumRigid Ryegrass172
49 SpainSpain 1992 Wheat diclofop-methyl 38 Inhibition of Acetyl CoA Carboxylase (A/1)
112Lolium rigidumRigid Ryegrass173
50 SpainSpain 1992 Orchards simazine 38 PSII inhibitors - Serine 264 Binders (C1 C2/5)
112Lolium rigidumRigid Ryegrass174
51 SpainSpain 2006 Orchards glyphosate 38 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass5332
52 SpainSpain 2016 Olive glyphosate, and oxyfluorfen 38 Multiple Resistance: 2 Sites of Action
Inhibition of Protoporphyrinogen Oxidase (E/14)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass17105
53 TunisiaTunisia 1996 Cereals diclofop-methyl 78 Inhibition of Acetyl CoA Carboxylase (A/1)
112Lolium rigidumRigid Ryegrass5028
54 TunisiaTunisia 2023 Wheat iodosulfuron-methyl-Na, mesosulfuron-methyl, and pyroxsulam 78 Inhibition of Acetolactate Synthase (B/2)
112Lolium rigidumRigid Ryegrass29275
55 TunisiaTunisia 2023 Wheat clodinafop-propargyl, iodosulfuron-methyl-Na, mesosulfuron-methyl, and pinoxaden 78 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase (A/1)
Inhibition of Acetolactate Synthase (B/2)
112Lolium rigidumRigid Ryegrass29276
56 United States (California) United StatesCalifornia1998 Almonds, and Orchards glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
112Lolium rigidumRigid Ryegrass1034
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