<b>HRAC Group 2</b> <font size='2'> (Legacy B) </font> resistant Bromus japonicus from United States, Kansas

INTRODUCTION		JAPANESE BROME
Japanese Brome (Bromus japonicus) is a monocot weed in the Poaceae family. In Kansas this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2007 and infests Winter 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.

QUIK STATS (last updated Jan 25, 2011 )
Common Name	Japanese Brome
Species	Bromus japonicus
Group	Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicides	imazamox, propoxycarbazone-Na, pyroxsulam, and sulfosulfuron
Location	United States, Kansas
Year	2007
Situation(s)	Winter wheat
Contributors - (Alphabetically)	Dallas Peterson
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Japanese Brome biotype with this Japanese 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 Japanese 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

Studies on the mechanism of resistance of Group 2 (Legacy B) resistant Japanese Brome from Kansas 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 Japanese Brome from Kansas please update the database.

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CONTRIBUTING WEED SCIENTISTS

DALLAS PETERSON

Professor and Extension Weed Specialist Kansas State University Department of Agronomy 3703 Throckmorton Plant Sciences Center 1712 Claflin Road Manhattan, KS 66506-0110, Kansas United States Email Dallas Peterson Web : Web Site Link

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

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Herbicide Resistant Japanese Brome Globally
(Bromus japonicus)

#

Country

FirstYear

Situation

Active Ingredients

Site of Action

1

United States (Kansas)

2007

Winter wheat

imazamox, propoxycarbazone-Na, pyroxsulam, and sulfosulfuron

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

Literature about Similar Cases

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Menegat, A. ; Kaiser, Y. ; Stephan, A. ; Ni HanWen ; Gerhards, R.. 2012. Chlorophyll fluorescence microscreening as a rapid detection method for herbicide resistance in grass weeds in North China Plain winter wheat production systems and beyond. Pakistan Journal of Weed Science Research 18 : 409 - 418.

The North China Plain (NCP) is one of the most important winter wheat production areas in the world. A double cropping system of winter wheat followed by summer maize in one year is the most common cropping practice in the NCP. However new crops and agricultural practices including chemical weed control measures were recently introduced in this area. Alopecurus spp., Aegilops squarrosa L. and Bromus japonicus Thunb. were found to be the most abundant grass weeds in the NCP winter wheat production system. In 2008 and 2009, A. japonicus seeds were collected from different locations in the NCP to conduct herbicide efficacy studies. Besides conventional glasshouse bioassays a rapid herbicide resistance test has been developed and tested. This new resistance test is based on chlorophyll fluorescence microscreenings for evaluation of the efficacy of herbicides on grass weeds grown in tissue culture plates filled with an agar-herbicide solution. In glasshouse bioassays for chlorotoluron a resistance factor of 3.5 was found for one of the NCP biotypes compared to the sensitive control biotype. The chlorophyll fluorescence microscreening clearly verified this result. Further studies showed that this method is also suitable for other herbicide modes of action like ALS and ACC inhibitors. Furthermore this method is easily transferable to other important grass weeds. Using the chlorophyll fluorescence assay, it becomes possible to evaluate efficacy for a large number of biotypes with a minimum requirement of time and space. Therefore it is well suited for high throughput resistance screenings, especially at locations where glasshouse space is a limiting factor. An accelerated identification of resistant grass weed biotypes and thus a prompt resistance management plan for the field will be of great importance for the North China Plain and other intensive agricultural areas in the world..

Menegat, A. ; Kaiser, Y. ; Stephan, A. ; Ni HanWen ; Gerhards, R.. 2011. Chlorophyll fluorescence microscreening as a rapid detection method for herbicide resistance in grass weeds in North China Plain winter wheat production systems and beyond. : 350 - 358.

The North China Plain (NCP) is one of the most important winter wheat production areas in the world. A double cropping system of winter wheat followed by summer maize in one year is the most common cropping practice in the NCP. However new crops and agricultural practices including chemical weed control measures were recently introduced in this area. Alopecurus spp., Aegilops squarrosa L. and Bromus japonicus Thunb. were found to be the most abundant grass weeds in the NCP winter wheat production system. In 2008 and 2009, A. japonicus seeds were collected from different locations in the NCP to conduct herbicide efficacy studies. Besides conventional glasshouse bioassays a rapid herbicide resistance test has been developed and tested. This new resistance test is based on chlorophyll fluorescence microscreenings for evaluation of the efficacy of herbicides on grass weeds grown in tissue culture plates filled with an agar-herbicide solution. In glasshouse bioassays for chlorotoluron a resistance factor of 3.5 was found for one of the NCP biotypes compared to the sensitive control biotype. The chlorophyll fluorescence microscreening clearly verified this result. Further studies showed that this method is also suitable for other herbicide modes of action like ALS and ACC inhibitors. Furthermore this method is easily transferable to other important grass weeds. Using the chlorophyll fluorescence assay, it becomes possible to evaluate efficacy for a large number of biotypes with a minimum requirement of time and space. Therefore it is well suited for high throughput resistance screenings, especially at locations where glasshouse space is a limiting factor. An accelerated identification of resistant grass weed biotypes and thus a prompt resistance management plan for the field will be of great importance for the North China Plain and other intensive agricultural areas in the world..

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