International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Urochloa panicoides)

EPSP synthase inhibitors (G/9)

Argentina, Tucumán
Liverseedgrass (Urochloa panicoides) is a monocot weed in the Poaceae family.  In Argentina this weed first evolved resistance to Group G/9 herbicides in 2017 and infests Corn (maize), and Soybean.   Group G/9 herbicides are known as EPSP synthase inhibitors (Inhibition of EPSP synthase).  Research has shown that these particular biotypes are resistant to glyphosate and they may be cross-resistant to other Group G/9 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 Mar 30, 2019 )

Common NameLiverseedgrass
SpeciesUrochloa panicoides
GroupEPSP synthase inhibitors (G/9)
LocationArgentina, Tucumán
Situation(s)Corn (maize), and Soybean
Contributors - (Alphabetically)Marcelo De La Vega, and Exequiel Varela 
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Confirmation Tests

Greenhouse trials comparing a known susceptible Liverseedgrass biotype with this Liverseedgrass biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.

Genetic studies on Group G/9 resistant Liverseedgrass 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 G/9 resistant Liverseedgrass from Argentina please update the database.
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Facultad Agronomía y Zootecnia - Universidad Nacional de Tucumán
Sanidad Vegetal
Av Kirchner 1900
San Miguel de Tucumán, 4000, Tucumán
Email Marcelo De La Vega
Ingeniero Agronomo - Estudiante de Posgrado
Facultad de Agronomia Y Zootecnia - UNT
Produccion Vegetal
Florentino Ameghino S/N
El Manantial, 4000, Tucuman
Email Exequiel Varela


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 Marcelo De La Vega, and Exequiel Varela for providing detailed information.
Herbicide Resistant Liverseedgrass Globally
(Urochloa panicoides)
Herbicide Resistant Liverseedgrass Globally
(Urochloa panicoides)
Drag a column header and drop it here to group by that column
Herbicide Resistant Liverseedgrass Globally
(Urochloa panicoides)
#CountryFirstYearSituationActive IngredientsSite of Action
1 ArgentinaArgentina 2017 Corn (maize), and Soybean glyphosate 48 EPSP synthase inhibitors (G/9)
171Urochloa panicoidesLiverseedgrass18158
2 Australia (Queensland) AustraliaQueensland1996 Cropland atrazine 1 Photosystem II inhibitors (C1/5)
171Urochloa panicoidesLiverseedgrass530
3 Australia (New South Wales ) AustraliaNew South Wales 2008 Sorghum, and Wheat glyphosate 1 EPSP synthase inhibitors (G/9)
171Urochloa panicoidesLiverseedgrass5362
Literature about Similar Cases

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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Sunday, September 22, 2019 .  Available
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