<b>HRAC Group 9</b> <font size='2'> (Legacy G) </font> resistant Salsola tragus from United States, Washington

INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 9 (LEGACY G) RESISTANT RUSSIAN-THISTLE
(Salsola tragus)

Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)

United States, Washington

INTRODUCTION		RUSSIAN-THISTLE
Russian-thistle (Salsola tragus) is a dicot weed in the Chenopodiaceae family. In Washington this weed first evolved resistance to Group 9 (Legacy G) herbicides in 2015 and infests Fallow. Group 9 (Legacy G) herbicides are known as Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (Inhibition of EPSP synthase). Research has shown that these particular biotypes are resistant to glyphosate and they may be cross-resistant to other Group 9 (Legacy G) 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 Apr 08, 2019 )
Common Name	Russian-thistle
Species	Salsola tragus
Group	Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
Herbicides	glyphosate
Location	United States, Washington
Year	2015
Situation(s)	Fallow
Contributors - (Alphabetically)	Ian Burke, Prashant Jha, Vipan Kumar, and Drew Lyon
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NOTES ABOUT THIS BIOTYPE

GENERAL

Drew Lyon

Weed Technology 2017 31:238–251

Glyphosate-Resistant Russian-thistle (Salsola tragus) Identified in Montana and Washington
Vipan Kumar, John F. Spring, Prashant Jha, Drew J. Lyon, and Ian C. Burke

Two putative glyphosate-resistant (GR) Russian-thistle accessions were collected from fallow fields (wheat-fallow rotation): one from Choteau County, MT (MT-R), and a second from Columbia County, WA (WA-R) in summer/fall of 2015. Greenhouse and outdoor/field whole-plant dose-response studies were conducted to confirm and characterize the levels of glyphosate resistance in these GR accessions relative to known glyphosate-susceptible accessions (MT-S and WA-S from MT and WA, respectively). Based on GR50 values of the progeny plants, the MT-R accession exhibited 4.5-fold and 5.9-fold resistance to glyphosate relative to the MT-S accession under greenhouse and outdoor conditions, respectively. The WA-R accession showed 3.0- to 5.0-fold resistance relative to the WA-S accession in greenhouse experiments, and 1.9- to 7.5-fold resistance in multi-site field experiments. In a separate greenhouse study on alternative POST herbicides to control GR Russian-thistle, bicyclopyrone plus bromoxynil, bromoxynil plus fluroxypyr, bromoxynil plus pyrasulfotole, bromoxynil plus MCPA, paraquat alone, paraquat plus metribuzin, saflufenacil alone, saflufenacil plus 2,4-D, and 2,4-D plus bromoxynil plus fluroxypyr provided effective control (≥95%) and shoot dry weight reduction (up to 98%) of GR accessions. This research confirms the first global case of field-evolved GR Russian-thistle. Best management practices (BMPs); including alternative, effective herbicide programs (based on multiple mechanisms of action highlighted in this study) need immediate implementation to prevent further spread of GR or evolution of multiple HR
Russian-thistle populations in this region.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Russian-thistle biotype with this Russian-thistle 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 9 resistant Russian-thistle 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 9 (Legacy G) resistant Russian-thistle from Washington please update the database.

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CONTRIBUTING WEED SCIENTISTS

IAN BURKE

Associate Professor - Weed Scientist Washington State University Department of Crop And Soil Sciences 163 Johnson Hall PO Box 646420 Pullman, 99164, Washington United States Email Ian Burke Web : Web Site Link

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

DREW LYON

Endowed Chair in Small Grains Extension and Research, Weed Science Washington State University Crop & Soil Sciences PO Box 646420 Pullman, 99164-6420, Washington United States Email Drew Lyon Web : Web Site Link

ACKNOWLEDGEMENTS
The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Washington have been instrumental in providing you this information. Particular thanks is given to Ian Burke, Prashant Jha, Vipan Kumar, and Drew Lyon for providing detailed information.

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Herbicide Resistant Russian-thistle Globally
(Salsola tragus)

Country

FirstYear

Situation

Active Ingredients

Site of Action

Argentina

2019

Soybean

glyphosate

Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)

Canada (Saskatchewan)

1989

Wheat

chlorsulfuron