INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 2 (LEGACY B) RESISTANT DOWNY BROME (CHEATGRASS)
(Bromus tectorum)


Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

United States, Montana
INTRODUCTION DOWNY BROME (CHEATGRASS)
Downy Brome (Cheatgrass) (Bromus tectorum) is a monocot weed in the Poaceae family.  In Montana this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2016 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, procarbazone-Na, and pyroxsulam 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.

If we do not have a picture for this weed, or you can provide a better picture (scan, digital camera etc) please please e-mail it to us.

QUIK STATS (last updated Mar 21, 2017 )

Common NameDowny Brome (Cheatgrass)
SpeciesBromus tectorum
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicidesimazamox, procarbazone-Na, and pyroxsulam
LocationUnited States, Montana
Year2016
Situation(s)Wheat
Contributors - (Alphabetically)Prashant Jha, and Vipan Kumar 
Edit this Case  |  Add New Case of Resistance  |  Add Note

ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory 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 2 resistant Downy Brome (Cheatgrass) indicate that the inheritance is determined by a one gene trait.  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 Group 2 (Legacy B) resistant Downy Brome (Cheatgrass) from Montana indicate that resistance is due to an altered target site.  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 Group 2 (Legacy B) resistant Downy Brome (Cheatgrass) from Montana please update the database.
 
Edit Case  |  Add Note  |  Add Article  |  Add New Case  |  

CONTRIBUTING WEED SCIENTISTS

PRASHANT JHA
Associate Professor-Weed Science
Montana State University-Bozeman
Southern Agricultural Research Center
748 Railroad Highway
Huntley, 59037, Montana
United States
Email Prashant Jha
Web   : Web Site Link
VIPAN KUMAR
Assistant Professor-Weed Science
Kansas State University
Agricultural Research Center-Hays
1232 240th Avenue
Hays, 67601, Kansas
United States
Email Vipan Kumar
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Montana have been instrumental in providing you this information. Particular thanks is given to Prashant Jha, and Vipan Kumar 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
Literature about Similar Cases

Page size:
select
Page: of 4
Items 1 to 5 of 18

Page size:
select
Page: of 4
Items 1 to 5 of 18

PERMISSION MUST BE OBTAINED FIRST if you intend to base a significant portion of a scientific paper on data derived from this site. Citation:
Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Tuesday, November 5, 2024 .  Available  www.weedscience.org Copyright © 1993- 2024 WeedScience.org All rights reserved. Fair use of this material is encouraged. Proper citation is requested.