<b>HRAC Group 9</b> <font size='2'> (Legacy G) </font> resistant Leptochloa virgata from Mexico

INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 9 (LEGACY G) RESISTANT TROPICAL SPRANGLETOP (JUDDSGRASS)
(Leptochloa virgata)

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

Mexico, Veracruz

INTRODUCTION		TROPICAL SPRANGLETOP (JUDDSGRASS)
Tropical Sprangletop (Juddsgrass) (Leptochloa virgata) is a monocot weed in the Poaceae family. In Mexico this weed first evolved resistance to Group 9 (Legacy G) herbicides in 2010 and infests Orchards. 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 Mar 14, 2012 )
Common Name	Tropical Sprangletop (Juddsgrass)
Species	Leptochloa virgata
Group	Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G)
Herbicides	glyphosate
Location	Mexico, Veracruz
Year	2010
Situation(s)	Orchards
Contributors - (Alphabetically)	Hugo Cruz-Hipólito, Rafael De Prado, Ja Dominguez Valenzuela, and Macrina Perez Lopez
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Tropical Sprangletop (Juddsgrass) biotype with this Tropical Sprangletop (Juddsgrass) 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 Tropical Sprangletop (Juddsgrass) 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 Tropical Sprangletop (Juddsgrass) from Mexico please update the database.

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CONTRIBUTING WEED SCIENTISTS

HUGO CRUZ-HIPÓLITO

Research Asociate Universidad De Córdoba Química Agrícola Y Edafología Campus Universitario De Rabanales Edif. C-3 3ª Planta Córdoba, 14002 Spain Email Hugo Cruz-Hipólito

RAFAEL DE PRADO

Research Asociate Universidad De Cordoba Qvimica Agricola Y Edafologa E T S Ingenieros Agronomos PO Box 119 Cordoba, E-14080, Andalusia Spain Email Rafael De Prado

JA DOMINGUEZ VALENZUELA

Phd Universidad Autónoma Chapingo Parasitología Agrícola Area De Malezas Departamento De Parasitología Agricola Texcoco, 56230, Andalusia Mexico Email Ja Dominguez Valenzuela

MACRINA PEREZ LOPEZ

Phd Student Universidad De Cordoba Quimica Agricola Y Edafologia Campus De Rabanales C-3 Edif. Marie Curie Carr. Nac. Km. 396 Cordoba, 14017, Andalusia Spain Email Macrina Perez Lopez

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 Hugo Cruz-Hipólito, Rafael De Prado, Ja Dominguez Valenzuela, and Macrina Perez Lopez for providing detailed information.

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Herbicide Resistant Tropical Sprangletop (Juddsgrass) Globally
(Leptochloa virgata)

Country

FirstYear

Situation

Active Ingredients

Site of Action

Mexico

2010

Orchards

glyphosate

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

Literature about Similar Cases

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Alcántara-de la Cruz, R., Rojano-Delgado, A.M., Giménez, M.J., Cruz-Hipolito, H.E., Domínguez-Valenzuela, J.A., Barro, F. and De Prado, R.. 2016. First resistance mechanisms characterization in glyphosate-resistant Leptochloa virgata. Frontiers in Plant Science 7 : 1742 - .

Leptochloa virgata (L.) P. Beauv. is an annual weed common in citrus groves in the states of Puebla and Veracruz, Mexico limiting their production. Since 2010, several L. virgata populations were identified as being resistant to glyphosate, but studies of their resistance mechanisms developed by this species have been conducted. In this work, three glyphosate-resistant populations (R8, R14, and R15) collected in citrus orchards from Mexico, were used to study their resistance mechanisms comparing them to one susceptible population (S). Dose-response and shikimic acid accumulation assays confirmed the glyphosate resistance of the three resistant populations. Higher doses of up to 720 g ae ha-1 (field dose) were needed to control by 50% plants of resistant populations. The S population absorbed between 7 and 13% more 14C-glyphosate than resistant ones, and translocated up to 32.2% of 14C-glyphosate to the roots at 96 h after treatment (HAT). The R8, R14, and R15 populations translocated only 24.5, 26.5, and 21.9%, respectively. The enzyme activity of 5-enolpyruvyl shikimate-3-phosphate synthase (EPSPS) was not different in the S, R8 and R14 populations. The R15 Population exhibited 165.9 times greater EPSPS activity. Additionally, this population showed a higher EPSPS basal activity and a substitution in the codon 106 from Proline to Serine in the EPSPS protein sequence. EPSPS gene expression in the R15 population was similar to that of S population. In conclusion, the three resistant L. virgata populations show reduced absorption and translocation of 14C-glyphosate. Moreover, a mutation and an enhanced EPSPS basal activity at target-site level confers higher resistance to glyphosate. These results describe for the first time the glyphosate resistance mechanisms developed by resistant L. virgata populations of citrus orchards from Mexico..

Suárez, L. ; Anzalone, A. ; Moreno, O.. 2004. Evaluation of halosulfuron-methyl herbicide for weed control in rice (Oryza sativa L.). Bioagro 16 : 173 - 182.

The efficiency of weed control and selectivity for rice of halosulfuron-methyl (0, 15, 30, 45 and 60 g a.i./ha) were investigated in Venezuela. The herbicide was applied at 26 days after sowing, and the variables studied were crop damage, crown number per plant, plant height, plant loss percentage, rice grain number per panicle, 1000-grain weight, rice yield, weed control percentage and weed soil coverage. The herbicide did not show phytotoxicity at the tested rates. High number of crowns and plant height were observed under herbicide treatment. The best Cyperaceae control (>90%) was obtained at 60 g a.i./ha, and this rate also showed good control (> 80%) of Ludwigia sp. and Ischaemum rugosum. Some weeds were tolerant of the herbicide, such as Leptochloa virgata and Echinochloa colonum [E. colona]..

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