(Digitaria insularis)

EPSP synthase inhibitors (G/9)

Argentina, La Rivera, Santa Fe
Sourgrass (Digitaria insularis) is a monocot weed in the Poaceae family.  In Argentina this weed first evolved resistance to Group G/9 herbicides in 2014 and infests 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 Sep 19, 2016 )

Common NameSourgrass
SpeciesDigitaria insularis
GroupEPSP synthase inhibitors (G/9)
LocationArgentina, La Rivera, Santa Fe
Contributors - (Alphabetically)Martín Marzetti 
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Confirmation Tests

Greenhouse trials comparing a known susceptible Sourgrass biotype with this Sourgrass 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 Sourgrass 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 Sourgrass from Argentina please update the database.
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Ing. Agri.
Gte. Programa Malezas Resistentes
Dorrego 1639 - Piso 2
Oficina A
Rosario, Santa Fe
Email Martín Marzetti


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 Martín Marzetti for providing detailed information.
Herbicide Resistant Sourgrass Globally
(Digitaria insularis)
Herbicide Resistant Sourgrass Globally
(Digitaria insularis)
Drag a column header and drop it here to group by that column
Herbicide Resistant Sourgrass Globally
(Digitaria insularis)
#CountryFirstYearSituationActive IngredientsSite of Action
1 ArgentinaArgentina 2014 Soybean glyphosate 48 EPSP synthase inhibitors (G/9)
239Digitaria insularisSourgrass13049
2 BrazilBrazil 2008 Corn (maize), and Soybean glyphosate 5 EPSP synthase inhibitors (G/9)
239Digitaria insularisSourgrass5350
3 BrazilBrazil 2016 Soybean fenoxaprop-P-ethyl, and haloxyfop-methyl 5 ACCase inhibitors (A/1)
239Digitaria insularisSourgrass13043
4 BrazilBrazil 2020 Soybean fenoxaprop-P-ethyl, glyphosate, and haloxyfop-methyl 5 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
EPSP synthase inhibitors (G/9)
239Digitaria insularisSourgrass19212
5 ParaguayParaguay 2005 Corn (maize), Cotton, Soybean, and Sunflower glyphosate 46 EPSP synthase inhibitors (G/9)
239Digitaria insularisSourgrass5351
Literature about Similar Cases

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PERMISSION MUST BE OBTAINED FIRST if you intend to base a significant portion of a scientific paper on data derived from this site. Citation:
Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Tuesday, April 20, 2021 .  Available Copyright © 1993- 2021 All rights reserved. Fair use of this material is encouraged. Proper citation is requested.