International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
HRAC GROUP 9 (LEGACY G) RESISTANT DOWNY BROME (CHEATGRASS)
(Bromus tectorum)


Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)

Canada, Alberta
INTRODUCTION DOWNY BROME (CHEATGRASS)
Downy Brome (Cheatgrass) (Bromus tectorum) is a monocot weed in the Poaceae family.  In Alberta this weed first evolved resistance to Group 9 (Legacy G) herbicides in 2021 and infests Canola.   Group 9 (Legacy G) herbicides are known as Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (Inhibition of EPSP synthase).  Research has shown that these particular biotypes are resistant to glyphosate and they may be cross-resistant to other Group 9 (Legacy G) 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 Oct 25, 2021 )

Common NameDowny Brome (Cheatgrass)
SpeciesBromus tectorum
GroupInhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
Herbicidesglyphosate
LocationCanada, Alberta
Year2021
Situation(s)Canola
Contributors - (Alphabetically)Charles Geddes 
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Downy Brome (Cheatgrass) biotype with this Downy Brome (Cheatgrass) 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 HRAC Group 9 resistant Downy Brome (Cheatgrass) 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

The mechanism of resistance for this biotype is either unknown or has not been entered in the database.  If you know anything about the mechanism of resistance for this biotype then please update the database.
 
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 9 (Legacy G) resistant Downy Brome (Cheatgrass) from Alberta please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

CHARLES GEDDES
Research Scientist
Agriculture and Agri-Food Canada
Weed Ecology and Cropping Systems
Science and Technology Branch
Lethbridge Research and Development Centre 5403 - 1st Avenue South Lethbridge
Lethbridge, T1J481, Alberta
Canada
Email Charles Geddes

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Alberta have been instrumental in providing you this information. Particular thanks is given to Charles Geddes for providing detailed information.
Herbicide Resistant Downy Brome (Cheatgrass) Globally
(Bromus tectorum)
Herbicide Resistant Downy Brome (Cheatgrass) Globally
(Bromus tectorum)
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Herbicide Resistant Downy Brome (Cheatgrass) Globally
(Bromus tectorum)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Canada (Alberta) CanadaAlberta2021 Canola glyphosate 7 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
40Bromus tectorumDowny Brome (Cheatgrass)21234
2 FranceFrance 1981 Corn (maize) atrazine 17 PSII inhibitors - Serine 264 Binders (C1 C2/5)
40Bromus tectorumDowny Brome (Cheatgrass)457
3 SpainSpain 1990 Wheat chlorotoluron 38 PSII inhibitors - Serine 264 Binders (C1 C2/5)
40Bromus tectorumDowny Brome (Cheatgrass)190
4 SpainSpain 1990 Orchards simazine 38 PSII inhibitors - Serine 264 Binders (C1 C2/5)
40Bromus tectorumDowny Brome (Cheatgrass)191
5 United States (Oregon) United StatesOregon1997 Kentucky bluegrass imazamox, primisulfuron-methyl, and sulfosulfuron 45 Inhibition of Acetolactate Synthase (B/2)
40Bromus tectorumDowny Brome (Cheatgrass)1112
6 United States (Oregon) United StatesOregon2005 Grass seed clethodim, fluazifop-butyl, quizalofop-ethyl, and sethoxydim 45 Inhibition of Acetyl CoA Carboxylase (A/1)
40Bromus tectorumDowny Brome (Cheatgrass)5375
7 United States (Montana) United StatesMontana2016 Wheat imazamox, procarbazone-Na, and pyroxsulam 45 Inhibition of Acetolactate Synthase (B/2)
40Bromus tectorumDowny Brome (Cheatgrass)15071
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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Sunday, May 22, 2022 .  Available  www.weedscience.org
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