INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 9 (LEGACY G) RESISTANT LARGE CRABGRASS
(Digitaria sanguinalis)


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

Argentina, Western part of Buenos Aires Province
INTRODUCTION LARGE CRABGRASS
Large Crabgrass (Digitaria sanguinalis) is a monocot weed in the Poaceae family.  In Argentina this weed first evolved resistance to Group 9 (Legacy G) herbicides in 2019 and infests Soybean.   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.

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QUIK STATS (last updated Apr 27, 2022 )

Common NameLarge Crabgrass
SpeciesDigitaria sanguinalis
GroupInhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
Herbicidesglyphosate
LocationArgentina, Western part of Buenos Aires Province
Year2019
Situation(s)Soybean
Contributors - (Alphabetically)Ramón Gigón, and Marcos Yanniccari 
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NOTES ABOUT THIS BIOTYPE

MECHANISM

Marcos Yanniccari

Pest Management Science - 2022 doi: 10.1002/ps.6940

A novel EPSPS Pro-106-His mutation confers the first case of glyphosate resistance in Digitaria sanguinalis

Marcos Yanniccari1, José Guadalupe Vázquez-García2, Ramón Gigón3, Candelario Palma- Bautista2, Martin Vila-Aiub4, and Rafael De Prado2 1 Chacra Experimental Integrada Barrow (MDA-INTA), National Scientific and Technical Research Council (CONICET), Faculty of Agronomy, National University of La Pampa, Argentina.  2Department of Agroforestry, Plant Biochemistry and Molecular Biology, University of Cordoba, Spain. 3Private Consultant in Weed Control, Argentina. 4 Department of Ecology, IFEVA-CONICET, Faculty of Agronomy, University of Buenos Aires (UBA), Argentina.

Abstract

BACKGROUND: Digitaria sanguinalis has been identified as a species at high risk of evolving herbicide resistance, but thus far, there are no records of resistance to glyphosate. This species is one of the most common weeds of summer crops in extensive cropping areas in Argentina. This weed shows an extended period of seedling emergence with several overlapping cohorts during spring and summer, and it is commonly controlled with glyphosate. However, a D. sanguinalis population was implicated as a putative glyphosate-resistant biotype based on poor control at recommended glyphosate doses.

  RESULTS: The field-collected D. sanguinalis population (Dgs R) from the Rolling Pampas has evolved glyphosate resistance. Differences in plant survival and shikimate levels after field recommended and higher glyphosate doses were evident between Dgs R and the known susceptible (Dgs S) population, and the resistance index was 5.1. No evidence of differential glyphosate absorption, translocation, metabolism, or basal EPSPS activity was found between Dgs S and Dgs R populations; however, a novel EPSPS Pro-106-His point substitution is likely the primary glyphosate resistance endowing mechanism. EPSPS in vitro enzymatic activity demonstrated that an 80-fold higher concentration of glyphosate is required in Dgs R to achieve similar EPSPS activity inhibition as in the Dgs S population.

CONCLUSION: This study reports the first global case of glyphosate resistance in D. sanguinalis. This yet novel transversion at the second position of the EPSPS 106 codon demonstrates the intensity of glyphosate pressure in selecting unexpected glyphosate resistance alleles if they retain EPSPS functionality.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Large Crabgrass biotype with this Large Crabgrass 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 Large Crabgrass 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 9 (Legacy G) resistant Large Crabgrass from Argentina 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 9 (Legacy G) resistant Large Crabgrass from Argentina please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

RAMÓN GIGÓN
Eng.agronomy Master Science weed management
ASACIM
Azcuenaga 320
TRES ARROYOS, 7500, Buenos Aires
Argentina
Email Ramón Gigón
MARCOS YANNICCARI
Dr
CONICET
Chacra Experimental Integrada Barrow
RN 3 km 487 cc 50
Tres Arroyos, 7500, Buenos Aires
Argentina
Email Marcos Yanniccari

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Argentina have been instrumental in providing you this information. Particular thanks is given to Ramón Gigón, and Marcos Yanniccari for providing detailed information.
Herbicide Resistant Large Crabgrass Globally
(Digitaria sanguinalis)
Herbicide Resistant Large Crabgrass Globally
(Digitaria sanguinalis)
Drag a column header and drop it here to group by that column
Herbicide Resistant Large Crabgrass Globally
(Digitaria sanguinalis)
#CountryFirstYearSituationActive IngredientsSite of Action
1 ArgentinaArgentina 2019 Soybean glyphosate 48 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
77Digitaria sanguinalisLarge Crabgrass23239
2 Australia (South Australia) AustraliaSouth Australia1993 Onions, and Vegetables fluazifop-butyl, haloxyfop-methyl, and imazethapyr 1 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
77Digitaria sanguinalisLarge Crabgrass16
3 Canada (Ontario) CanadaOntario2011 Carrots, and Onions clethodim, fenoxaprop-ethyl, fluazifop-butyl, quizalofop-ethyl, and sethoxydim 7 Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
77Digitaria sanguinalisLarge Crabgrass5678
4 ChinaChina 2010 Corn (maize) nicosulfuron 9 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
77Digitaria sanguinalisLarge Crabgrass5656
5 ChinaChina 2011 Cotton quizalofop-ethyl 9 Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
77Digitaria sanguinalisLarge Crabgrass5672
6 Czech RepublicCzech Republic 2005 Railways atrazine 12 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
77Digitaria sanguinalisLarge Crabgrass5263
7 FranceFrance 1983 Corn (maize) atrazine 17 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
77Digitaria sanguinalisLarge Crabgrass461
8 FranceFrance 2005 Carrots cycloxydim, fluazifop-butyl, haloxyfop-methyl, and quizalofop-ethyl 17 Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
77Digitaria sanguinalisLarge Crabgrass6748
9 FranceFrance 2015 Corn (maize) foramsulfuron, and nicosulfuron 17 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
77Digitaria sanguinalisLarge Crabgrass11010
10 ItalyItaly 2006 Soybean cycloxydim, and fluazifop-butyl 24 Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
77Digitaria sanguinalisLarge Crabgrass5355
11 PolandPoland 1995 Orchards atrazine 33 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
77Digitaria sanguinalisLarge Crabgrass377
12 United States (Wisconsin) United StatesWisconsin1992 Carrots, and Onions fluazifop-butyl, and sethoxydim 45 Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
77Digitaria sanguinalisLarge Crabgrass417
13 United States (Georgia) United StatesGeorgia2008 Turf sethoxydim 45 Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
77Digitaria sanguinalisLarge Crabgrass7787
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