INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE
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Herbicide Resistant Perennial Ryegrass Globally
(Lolium perenne)
Herbicide Resistant Perennial Ryegrass Globally
(Lolium perenne)
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Herbicide Resistant Perennial Ryegrass Globally
(Lolium perenne)
#CountryFirstYearSituationActive IngredientsSite of Action
1 ArgentinaArgentina 2008 Soybean, Spring Barley, and Wheat glyphosate 48 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		111Lolium perennePerennial Ryegrass5487
2 ChileChile 2001 Cereals clodinafop-propargyl, and diclofop-methyl 8 Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
 		111Lolium perennePerennial Ryegrass5397
3 DenmarkDenmark 2016 Wheat clodinafop-propargyl, and iodosulfuron-methyl-Na 13 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)
 		111Lolium perennePerennial Ryegrass15077
4 GermanyGermany 2008 Wheat iodosulfuron-methyl-Na, pinoxaden, and pyroxsulam 18 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)
 		111Lolium perennePerennial Ryegrass5385
5 New ZealandNew Zealand 2012 Grapes glyphosate 30 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		111Lolium perennePerennial Ryegrass6750
6 New ZealandNew Zealand 2014 Wheat chlorsulfuron, iodosulfuron-methyl-Na, pyroxsulam, thifensulfuron-methyl, and tribenuron-methyl 30 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		111Lolium perennePerennial Ryegrass18201
7 New ZealandNew Zealand 2015 Grapes amitrole, glufosinate-ammonium, and glyphosate 30 Multiple Resistance: 3 Sites of Action
Inhibition of Lycopene Cyclase HRAC Group 34 (Legacy F3)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
Inhibition of Glutamine Synthetase HRAC Group 10 (Legacy H)
 		111Lolium perennePerennial Ryegrass14055
8 PortugalPortugal 2013 Grapes glyphosate 34 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
 		111Lolium perennePerennial Ryegrass7825
9 United States (California) United StatesCalifornia1989 Railways, and Roadsides sulfometuron-methyl 45 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		111Lolium perennePerennial Ryegrass396
10 United States (Texas) United StatesTexas1989 Roadsides sulfometuron-methyl 45 Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
 		111Lolium perennePerennial Ryegrass397
HRAC Global Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Sunday, October 4, 2026.  Available at  www.weedscience.org

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