International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
MULTIPLE RESISTANT ITALIAN RYEGRASS
(Lolium perenne ssp. multiflorum)


Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)

Denmark
INTRODUCTION ITALIAN RYEGRASS
Italian Ryegrass (Lolium perenne ssp. multiflorum) is a monocot weed in the Poaceae family.  In Denmark this weed first evolved multiple resistance (to 2 herbicide sites of action) in 2010 and infests Winter wheat.  Multiple resistance has evolved to herbicides in the Groups A/1, and B/2.  These particular biotypes are known to have resistance to clodinafop-propargyl, florasulam, iodosulfuron-methyl-sodium, mesosulfuron-methyl, and pyroxsulam and they may be cross-resistant to other herbicides in the Groups A/1, and B/2.

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 May 07, 2017 )

Common NameItalian Ryegrass
SpeciesLolium perenne ssp. multiflorum
GroupACCase inhibitors (A/1)
ALS inhibitors (B/2)
Herbicidesclodinafop-propargyl, florasulam, iodosulfuron-methyl-sodium, mesosulfuron-methyl, and pyroxsulam
LocationDenmark
Year2010
Situation(s)Winter wheat
Contributors - (Alphabetically)Solvejg Mathiassen 
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NOTES ABOUT THIS BIOTYPE

GENERAL

Solvejg Mathiassen

April 2017 Update

Lolium multiflorum

42 verified cases. Most of these cases are seed samples sent by farmers or consultants on suspicion of resistance. They have been tested in pot experiments including a susceptible and a resistant reference population. In most cases clodinafop and iodosulfuron have been used in the tests. From 2014 mesosulfuron + iodosulfuron (Atlantis) and florasulam + pyroxsulam (Broadway) have often been included in the test.  Most often we find resistance to ALS inhibitors, and sometimes to ACCase inhibitors as well. The resistance factors indicate that the most common mechanism of resistance is enhanced metabolism.  A survey on untreated plots in agricultural fields all over Denmark showed that 15% of the fields were infested by resistant L.multiflorum (to be presented in Denver in May). Genotyping: Molecular analysis of 19 populations revealed a single change of the ALS gene at position 574 in two populations, and of the ACCase gene at position 2041 in one population. Higher expression of metabolic related genes was identified in individuals from resistant populations. References: Mahmood K., Mathiassen S.K, Kristensen M., Kudsk P. (2016): Multiple Herbicide Resistance in Lolium multiflorum and Identification of Conserved Regulatory Element of Herbicide Resistance Genes. Frontiers in Plant Science, vol. 7, 1160, 08.2016.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Italian Ryegrass biotype with this Italian 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 A, B/1, 2 resistant Italian 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 multiple resistant Italian Ryegrass from Denmark indicate that resistance is due to enhanced metabolism.  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 multiple resistant Italian Ryegrass from Denmark please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

SOLVEJG MATHIASSEN
Senior Scientist
Aarhus University, Science and Technology
Dept. of Agroecology
P.o. Box 30
Slagelse, 4200, Slagelse Municipality
Denmark
Email Solvejg Mathiassen

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Denmark have been instrumental in providing you this information. Particular thanks is given to Solvejg Mathiassen for providing detailed information.
Herbicide Resistant Italian Ryegrass Globally
(Lolium perenne ssp. multiflorum)
Herbicide Resistant Italian Ryegrass Globally
(Lolium perenne ssp. multiflorum)
Drag a column header and drop it here to group by that column
Herbicide Resistant Italian Ryegrass Globally
(Lolium perenne ssp. multiflorum)
#CountryFirstYearSituationActive IngredientsSite of Action
1 ArgentinaArgentina 2007 Cereals glyphosate 48 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5352
2 ArgentinaArgentina 2009 diclofop-methyl 48 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass5586
3 ArgentinaArgentina 2010 Wheat glyphosate, iodosulfuron-methyl-sodium, and pyroxsulam 48 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5599
4 BrazilBrazil 2003 Orchards, and Soybean glyphosate 5 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5205
5 BrazilBrazil 2010 Wheat iodosulfuron-methyl-sodium 5 ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass5546
6 BrazilBrazil 2010 Corn (maize), Soybean, and Wheat clethodim, and glyphosate 5 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5547
7 BrazilBrazil 2016 Wheat clethodim, and iodosulfuron-methyl-sodium 5 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass15057
8 BrazilBrazil 2017 Corn (maize), Soybean, and Wheat glyphosate, iodosulfuron-methyl-sodium, and pyroxsulam 5 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass15063
9 ChileChile 1998 Canola, Lupins, and Wheat clodinafop-propargyl, diclofop-methyl, and haloxyfop-methyl 8 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass5105
10 ChileChile 2001 Fruit, and Orchards glyphosate 8 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5096
11 ChileChile 2002 Wheat flucarbazone-sodium, glyphosate, glyphosate-trimesium, and iodosulfuron-methyl-sodium 8 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5371
12 ChileChile 2005 Canola, Lupins, and Wheat clethodim, clodinafop-propargyl, diclofop-methyl, flucarbazone-sodium, iodosulfuron-methyl-sodium, pinoxaden, and tepraloxydim 8 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass5424
13 ChileChile 2006 Lupins clethodim, clodinafop-propargyl, diclofop-methyl, glyphosate, haloxyfop-methyl, and pinoxaden 8 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5445
14 ChileChile 2007 Spring Barley clethodim, flucarbazone-sodium, glyphosate, haloxyfop-methyl, iodosulfuron-methyl-sodium, pinoxaden, and tepraloxydim 8 Multiple Resistance: 3 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5452
15 DenmarkDenmark 2010 Winter wheat clodinafop-propargyl, florasulam, iodosulfuron-methyl-sodium, mesosulfuron-methyl, and pyroxsulam 13 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass5676
16 FranceFrance 1993 Wheat diclofop-methyl 17 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass549
17 ItalyItaly 1995 Alfalfa, and Durum wheat clodinafop-propargyl, cycloxydim, diclofop-methyl, pinoxaden, quizalofop-P-ethyl, sethoxydim, and tralkoxydim 24 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass8906
18 ItalyItaly 2002 Durum wheat clodinafop-propargyl, cycloxydim, diclofop-methyl, iodosulfuron-methyl-sodium, mesosulfuron-methyl, pinoxaden, sethoxydim, and tralkoxydim 24 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass1134
19 ItalyItaly 2005 Durum wheat iodosulfuron-methyl-sodium, and mesosulfuron-methyl 24 ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass8907
20 ItalyItaly 2008 Wheat clodinafop-propargyl, cycloxydim, glyphosate, and pinoxaden 24 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass8902
21 ItalyItaly 2012 Wheat glyphosate, iodosulfuron-methyl-sodium, and mesosulfuron-methyl 24 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass8903
22 JapanJapan 2011 Rice Paddy Levee glyphosate 25 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass7770
23 New ZealandNew Zealand 2012 Grapes glyphosate 30 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass6749
24 New ZealandNew Zealand 2015 Grapefruit amitrole, glufosinate-ammonium, and glyphosate 30 Multiple Resistance: 3 Sites of Action
Carotenoid biosynthesis (unknown target) (F3/11)
EPSP synthase inhibitors (G/9)
Glutamine synthase inhibitors (H/10)
110Lolium perenne ssp. multiflorumItalian Ryegrass14056
25 SpainSpain 2006 Orchards glyphosate 38 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5331
26 SwitzerlandSwitzerland 2011 Orchards glyphosate 41 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass11007
27 United KingdomUnited Kingdom 1990 Canola, Cereals, and Wheat cycloxydim, diclofop-methyl, fluazifop-P-butyl, pinoxaden, and tralkoxydim 44 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass356
28 United KingdomUnited Kingdom 1990 Wheat isoproturon 44 PSII inhibitor (Ureas and amides) (C2/7)
110Lolium perenne ssp. multiflorumItalian Ryegrass5080
29 United KingdomUnited Kingdom 2012 Cereals mesosulfuron-methyl, and pyroxsulam 44 ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass10968
30 United States (Oregon) United StatesOregon1987 Wheat diclofop-methyl 45 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass320
31 United States (North Carolina) United StatesNorth Carolina1990 Wheat diclofop-methyl, and sethoxydim 45 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass259
32 United States (South Carolina) United StatesSouth Carolina1990 Wheat diclofop-methyl 45 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass268
33 United States (Idaho) United StatesIdaho1991 Canola, Chickpea, Lentils, Peas, and Wheat clodinafop-propargyl, diclofop-methyl, quizalofop-P-ethyl, and sethoxydim 45 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass519
34 United States (Virginia) United StatesVirginia1993 Wheat diclofop-methyl 45 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass275
35 United States (Mississippi) United StatesMississippi1995 Roadsides sulfometuron-methyl 45 ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass526
36 United States (Georgia) United StatesGeorgia1995 Canola, and Wheat diclofop-methyl, and sethoxydim 45 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass543
37 United States (Arkansas) United StatesArkansas1995 Wheat chlorsulfuron, diclofop-methyl, and fenoxaprop-P-ethyl 45 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass1097
38 United States (Maryland) United StatesMaryland1998 Wheat diclofop-methyl 45 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass1084
39 United States (Arkansas) United StatesArkansas2003 Wheat chlorsulfuron, imazamox, mesosulfuron-methyl, and sulfometuron-methyl 45 ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass5399
40 United States (Oregon) United StatesOregon2004 Orchards glyphosate 45 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5249
41 United States (Kentucky) United StatesKentucky2004 Wheat diclofop-methyl 45 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass7877
42 United States (Idaho) United StatesIdaho2005 Canola, Chickpea, Lentils, Peas, and Wheat clethodim, clodinafop-propargyl, diclofop-methyl, flufenacet, quizalofop-P-ethyl, and triasulfuron 45 Multiple Resistance: 3 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
Long chain fatty acid inhibitors (K3/15)
110Lolium perenne ssp. multiflorumItalian Ryegrass5280
43 United States (Mississippi) United StatesMississippi2005 Cotton, and Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5309
44 United States (Arkansas) United StatesArkansas2005 Wheat clodinafop-propargyl, diclofop-methyl, and pinoxaden 45 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass5409
45 United States (Tennessee) United StatesTennessee2006 Winter wheat diclofop-methyl 45 ACCase inhibitors (A/1)
110Lolium perenne ssp. multiflorumItalian Ryegrass5316
46 United States (North Carolina) United StatesNorth Carolina2007 Wheat mesosulfuron-methyl 45 ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass7818
47 United States (North Carolina) United StatesNorth Carolina2007 Wheat diclofop-methyl, imazamox, mesosulfuron-methyl, pinoxaden, and pyroxsulam 45 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass7856
48 United States (Arkansas) United StatesArkansas2008 Wheat glyphosate 45 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5401
49 United States (California) United StatesCalifornia2008 Orchards, and Roadsides glyphosate 45 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass5698
50 United States (Georgia) United StatesGeorgia2009 Wheat diclofop-methyl, and mesosulfuron-methyl 45 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass5500
51 United States (North Carolina) United StatesNorth Carolina2009 Corn (maize), and Cotton glyphosate 45 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass7811
52 United States (Oregon) United StatesOregon2010 Orchards glufosinate-ammonium, and glyphosate 45 Multiple Resistance: 2 Sites of Action
EPSP synthase inhibitors (G/9)
Glutamine synthase inhibitors (H/10)
110Lolium perenne ssp. multiflorumItalian Ryegrass5564
53 United States (South Carolina) United StatesSouth Carolina2010 Wheat diclofop-methyl, mesosulfuron-methyl, and pyroxsulam 45 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass7782
54 United States (Delaware) United StatesDelaware2012 Wheat mesosulfuron-methyl 45 ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass5709
55 United States (Tennessee) United StatesTennessee2012 Corn (maize) glyphosate 45 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass6753
56 United States (Missouri) United StatesMissouri2013 Corn (maize), Soybean, and Wheat mesosulfuron-methyl, and pinoxaden 45 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass7809
57 United States (Kentucky) United StatesKentucky2013 Wheat mesosulfuron-methyl, and pyroxsulam 45 ALS inhibitors (B/2)
110Lolium perenne ssp. multiflorumItalian Ryegrass7891
58 United States (Louisiana) United StatesLouisiana2014 Corn (maize), Cotton, and Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass8898
59 United States (California) United StatesCalifornia2015 Grapes, and Orchards glufosinate-ammonium 45 Glutamine synthase inhibitors (H/10)
110Lolium perenne ssp. multiflorumItalian Ryegrass13044
60 United States (California) United StatesCalifornia2015 Alfalfa, Grapes, and Orchards glyphosate, paraquat, and sethoxydim 45 Multiple Resistance: 3 Sites of Action
ACCase inhibitors (A/1)
PSI Electron Diverter (D/22)
EPSP synthase inhibitors (G/9)
110Lolium perenne ssp. multiflorumItalian Ryegrass15066
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