INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 9 (LEGACY G) RESISTANT LAX PANICGRASS
(Steinchisma laxum)


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

Mexico, Central zone and Llanos plains
INTRODUCTION LAX PANICGRASS
Lax Panicgrass (Steinchisma laxum) is a monocot weed in the Poaceae family.  In Mexico this weed first evolved resistance to Group 9 (Legacy G) herbicides in 2023 and infests Rice.   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 Jul 23, 2023 )

Common NameLax Panicgrass
SpeciesSteinchisma laxum
GroupInhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
Herbicidesglyphosate
LocationMexico, Central zone and Llanos plains
Year2023
Situation(s)Rice
Contributors - (Alphabetically)Rafael De Prado, Ian Heap, Veronica Hoyos, Candelario Palma-Bautista, and Guido Plaza 
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NOTES ABOUT THIS BIOTYPE

GENERAL

Rafael De Prado

Divergence in glyphosate susceptibility between Steinchisma laxum populations involves a Pro106Ser mutation.
Author(s) : Hoyos, V. ;  Plaza, G. ;  Palma-Bautista, C. ;  Vázquez-García, J. G. ;  Dominguez-Valenzuela, J. A. ;  Alcántara-De Cruz, R. la ;  Prado, R. de
Author Affiliation : Departamento de Ciencias Biológicas, Universidad Nacional de Colombia, Palmira 763533, Colombia.
Author Email : ricardo.cruz@ufscar.br
Journal article : Plants 2023 Vol.12 No.18 ref.46

Abstract : The characterization of the mechanisms conferring resistance to herbicides in weeds is essential for developing effective management programs. This study was focused on characterizing the resistance level and the main mechanisms that confer resistance to glyphosate in a resistant (R) Steinchisma laxum population collected in a Colombian rice field in 2020. The R population exhibited 11.2 times higher resistance compared to a susceptible (S) population. Non-target site resistance (NTSR) mechanisms that reduced absorption and impaired translocation and glyphosate metabolism were not involved in the resistance to glyphosate in the R population. Evaluating the target site resistance mechanisms by means of enzymatic activity assays and EPSPS (5-enolpyruvylshikimate-3-phosphate synthase) gene sequencing, the mutation Pro106Ser was found in R plants of S. laxum. These findings are crucial for managing the spread of S. laxum resistance in Colombia. To effectively control S. laxum in the future, it is imperative that farmers use herbicides with different mechanisms of action in addition to glyphosate and adopt Integrate Management Programs to control weeds in rice fields of the central valleys of Colombia. ISSN : 2223-7747 DOI : 10.3390/plants12183315

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Lax Panicgrass biotype with this Lax Panicgrass 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 Lax Panicgrass 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 Lax Panicgrass from Mexico 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 Lax Panicgrass from Mexico please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

RAFAEL DE PRADO
Universidad De Cordoba
Qvimica Agricola Y Edafologa
E T S Ingenieros Agronomos
PO Box 119
Cordoba, E-14080, Andalusia
Spain
Email Rafael De Prado
IAN HEAP
Director
International Survey of Herbicide-Resistant Weeds
Qvimica Agricola Y Edafologa
E T S Ingenieros Agronomos
P.O. Box 1365
Corvallis, 97339, Oregon
United States
Email Ian Heap
Web   : Web Site Link
VERONICA HOYOS
Director
Universidad del Magdalena
Engineering School
Calle 32 22-08
Santa Marta, 470004, Magdalena
Colombia
Email Veronica Hoyos
Web   : Web Site Link
CANDELARIO PALMA-BAUTISTA
Research Associate
University of Cordoba
Department of Agricultural Chemistry and Edaphology
Rabanales University Campus
Building C-3 3rd Floor
Cordoba, 14071, Cordoba
Spain
Email Candelario Palma-Bautista
Web   : Web Site Link
GUIDO PLAZA
Associate Professor
Universidad Nacional de Colombia
Agronomy Department
Carrera 30 45-03 Edificio 500 Of 236
Bogot√°, 111321, Cundinamarca
Colombia
Email Guido Plaza
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Mexico have been instrumental in providing you this information. Particular thanks is given to Rafael De Prado, Ian Heap, Veronica Hoyos, Candelario Palma-Bautista, and Guido Plaza for providing detailed information.
Herbicide Resistant Lax Panicgrass Globally
(Steinchisma laxum)
Herbicide Resistant Lax Panicgrass Globally
(Steinchisma laxum)
Drag a column header and drop it here to group by that column
Herbicide Resistant Lax Panicgrass Globally
(Steinchisma laxum)
#CountryFirstYearSituationActive IngredientsSite of Action
1 MexicoMexico 2023 Rice glyphosate 29 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
1358Steinchisma laxumLax Panicgrass27271
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Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Thursday, July 18, 2024 .  Available  www.weedscience.org Copyright ¬© 1993- 2024 WeedScience.org All rights reserved. Fair use of this material is encouraged. Proper citation is requested.