INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 2 (LEGACY B) RESISTANT CHEAT (RYE BROME)
(Bromus secalinus)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

United States, Oklahoma
INTRODUCTION CHEAT (RYE BROME)
Cheat (Rye Brome) (Bromus secalinus) is a monocot weed in the Poaceae family.  In Oklahoma this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2009 and infests Wheat.   Group 2 (Legacy B) herbicides are known as Inhibition of Acetolactate Synthase (Inhibition of Acetolactate Synthase ).  Research has shown that these particular biotypes are resistant to imazamox, propoxycarbazone-Na, pyroxsulam, and sulfosulfuron and they may be cross-resistant to other Group 2 (Legacy B) 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 Mar 14, 2011 )

Common NameCheat (Rye Brome)
SpeciesBromus secalinus
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicidesimazamox, propoxycarbazone-Na, pyroxsulam, and sulfosulfuron
LocationUnited States, Oklahoma
Year2009
Situation(s)Wheat
Contributors - (Alphabetically)Joe Armstrong 
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Cheat (Rye Brome) biotype with this Cheat (Rye Brome) 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 2 resistant Cheat (Rye Brome) 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 2 (Legacy B) resistant Cheat (Rye Brome) from Oklahoma please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

JOE ARMSTRONG
Retired: Weed Science Extension Specialist
Retired: Oklahoma State University
Retired
368 Ag Hall
Stillwater, 74078, Oklahoma
United States
Email Joe Armstrong

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Oklahoma have been instrumental in providing you this information. Particular thanks is given to Joe Armstrong for providing detailed information.
Herbicide Resistant Cheat (Rye Brome) Globally
(Bromus secalinus)
Herbicide Resistant Cheat (Rye Brome) Globally
(Bromus secalinus)
Drag a column header and drop it here to group by that column
Herbicide Resistant Cheat (Rye Brome) Globally
(Bromus secalinus)
#CountryFirstYearSituationActive IngredientsSite of Action
1 United States (Kansas) United StatesKansas2007 Winter wheat imazamox, propoxycarbazone-Na, pyroxsulam, and sulfosulfuron 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
 		245Bromus secalinusCheat (Rye Brome)5446
2 United States (Oklahoma) United StatesOklahoma2009 Wheat imazamox, propoxycarbazone-Na, pyroxsulam, and sulfosulfuron 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
 		245Bromus secalinusCheat (Rye Brome)5527
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Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Tuesday, November 4, 2025 .  Available  www.weedscience.org Copyright © 1993- 2025 WeedScience.org All rights reserved. Fair use of this material is encouraged. Proper citation is requested.