INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 1 (LEGACY A) RESISTANT DOWNY BROME (CHEATGRASS)
(Bromus tectorum)


Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)

United States, Oregon
INTRODUCTION DOWNY BROME (CHEATGRASS)
Downy Brome (Cheatgrass) (Bromus tectorum) is a monocot weed in the Poaceae family.  In Oregon this weed first evolved resistance to Group 1 (Legacy A) herbicides in 2005 and infests Grass seed.   Group 1 (Legacy A) herbicides are known as Inhibition of Acetyl CoA Carboxylase (Inhibition of Acetyl CoA Carboxylase ).  Research has shown that these particular biotypes are resistant to clethodim, fluazifop-butyl, quizalofop-ethyl, and sethoxydim and they may be cross-resistant to other Group 1 (Legacy A) 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 Apr 15, 2009 )

Common NameDowny Brome (Cheatgrass)
SpeciesBromus tectorum
GroupInhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
Herbicidesclethodim, fluazifop-butyl, quizalofop-ethyl, and sethoxydim
LocationUnited States, Oregon
Year2005
Situation(s)Grass seed
Contributors - (Alphabetically)Daniel Ball 
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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 1 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 1 (Legacy A) resistant Downy Brome (Cheatgrass) from Oregon please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

DANIEL BALL
Professor Of Weed Science
Oregon State University
Columbia Basin Agricultural Research Center
48037 Tubbs Ranch Road P. O. Box 370
Pendleton, 97801, Oregon
United States
Email Daniel Ball
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Oregon have been instrumental in providing you this information. Particular thanks is given to Daniel Ball for providing detailed information.
Herbicide Resistant Downy Brome (Cheatgrass) Globally
(Bromus tectorum)
Herbicide Resistant Downy Brome (Cheatgrass) Globally
(Bromus tectorum)
Drag a column header and drop it here to group by that column
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 ( HRAC Group 9 (Legacy G)
40Bromus tectorumDowny Brome (Cheatgrass)21234
2 FranceFrance 1981 Corn (maize) atrazine 17 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
40Bromus tectorumDowny Brome (Cheatgrass)457
3 SpainSpain 1990 Wheat chlorotoluron 38 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
40Bromus tectorumDowny Brome (Cheatgrass)190
4 SpainSpain 1990 Orchards simazine 38 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
40Bromus tectorumDowny Brome (Cheatgrass)191
5 United States (Oregon) United StatesOregon1997 Kentucky bluegrass imazamox, primisulfuron-methyl, and sulfosulfuron 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
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 ( HRAC Group 1 (Legacy A)
40Bromus tectorumDowny Brome (Cheatgrass)5375
7 United States (Montana) United StatesMontana2016 Wheat imazamox, procarbazone-Na, and pyroxsulam 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
40Bromus tectorumDowny Brome (Cheatgrass)15071
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