<b>HRAC Group 2</b> <font size='2'> (Legacy B) </font> resistant Poa trivialis from France

INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 2 (LEGACY B) RESISTANT ROUGHSTALK BLUEGRASS
(Poa trivialis)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

France

INTRODUCTION		ROUGHSTALK BLUEGRASS
Roughstalk Bluegrass (Poa trivialis) is a monocot weed in the Poaceae family. In France this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2012 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 iodosulfuron-methyl-Na, and mesosulfuron-methyl 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.

QUIK STATS (last updated Nov 19, 2019 )
Common Name	Roughstalk Bluegrass
Species	Poa trivialis
Group	Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicides	iodosulfuron-methyl-Na, and mesosulfuron-methyl
Location	France
Year	2012
Situation(s)	Wheat
Contributors - (Alphabetically)	Christophe Délye
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ACADEMIC ASPECTS

Confirmation Tests

Laboratory trials comparing a known susceptible Roughstalk Bluegrass biotype with this Roughstalk Bluegrass 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 Roughstalk Bluegrass 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 Roughstalk Bluegrass from France please update the database.

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CONTRIBUTING WEED SCIENTISTS

CHRISTOPHE DÉLYE

Chargé de Recherches INRA Agroécologie 17 rue de Sully Dijon, F-21000, Burgundy France Email Christophe Délye Web : Web Site Link

ACKNOWLEDGEMENTS
The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in France have been instrumental in providing you this information. Particular thanks is given to Christophe Délye for providing detailed information.

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Herbicide Resistant Roughstalk Bluegrass Globally
(Poa trivialis)

Country

FirstYear

Situation

Active Ingredients

Site of Action

France

2012

Wheat

iodosulfuron-methyl-Na, and mesosulfuron-methyl

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Ireland

2023

Wheat

iodosulfuron-methyl-Na, mesosulfuron-methyl, and propoxycarbazone-Na

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

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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 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.