International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Tridax procumbens)

EPSP synthase inhibitors (G/9)

Australia, Western Australia
Coat Buttons (Tridax procumbens) is a dicot weed in the Asteraceae family.  In Western Australia this weed first evolved resistance to Group G/9 herbicides in 2016 and infests Sandalwood Plantation.   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 Oct 27, 2016 )

Common NameCoat Buttons
SpeciesTridax procumbens
GroupEPSP synthase inhibitors (G/9)
LocationAustralia, Western Australia
Situation(s)Sandalwood Plantation
Contributors - (Alphabetically)Stephen Powles 
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Stephen Powles
A unique mutation at position 102 of the EPSPS gene that endows the resistance.

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Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Coat Buttons biotype with this Coat Buttons 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 Coat Buttons 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 G/9 resistant Coat Buttons from Western Australia 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 G/9 resistant Coat Buttons from Western Australia please update the database.
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Professor And Research Director
University Of Western Australia
School Of Plant Biology
2276 Dahlk Circle
Crawley, 6009, Western Australia
Email Stephen Powles
Web   : Web Site Link


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Western Australia have been instrumental in providing you this information. Particular thanks is given to Stephen Powles for providing detailed information.
Herbicide Resistant Coat Buttons Globally
(Tridax procumbens)
Herbicide Resistant Coat Buttons Globally
(Tridax procumbens)
Drag a column header and drop it here to group by that column
Herbicide Resistant Coat Buttons Globally
(Tridax procumbens)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Australia (Western Australia) AustraliaWestern Australia2016 Sandalwood Plantation glyphosate 1 EPSP synthase inhibitors (G/9)
333Tridax procumbensCoat Buttons14052
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