International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Euphorbia heterophylla)

PSII inhibitors - Serine 264 Binders (C2/7)

Wild Poinsettia (Euphorbia heterophylla) is a dicot weed in the Euphorbiaceae family.  In Ecuador this weed first evolved resistance to Group C2/7 herbicides in 1990 and infests Corn (maize), and Soybean.   Group C2/7 herbicides are known as PSII inhibitors - Serine 264 Binders (Inhbition of Photosynthesis at PSll - Serine 264 Binders ).  Research has shown that these particular biotypes are resistant to linuron and they may be cross-resistant to other Group C2/7 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 15, 2000 )

Common NameWild Poinsettia
SpeciesEuphorbia heterophylla
GroupPSII inhibitors - Serine 264 Binders (C2/7)
Situation(s)Corn (maize), and Soybean
Contributors - (Alphabetically)Jose Taro Garcia 
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Jose Taro Garcia
Patricia, Pichilineur in the towns of Santo Domineo, Esmerdiass?, and Queuedos.

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Confirmation Tests

Field, and Greenhouse trials comparing a known susceptible Wild Poinsettia biotype with this Wild Poinsettia 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 C2/7 resistant Wild Poinsettia 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 C2/7 resistant Wild Poinsettia from Ecuador please update the database.
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Inst. Nacional De Invest. Pecuarias
Coord. Nacional De Malezas
General Argolo 337/201
Portoviejo, AA 100


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Ecuador have been instrumental in providing you this information. Particular thanks is given to Jose Taro Garcia for providing detailed information.
Herbicide Resistant Wild Poinsettia Globally
(Euphorbia heterophylla)
Herbicide Resistant Wild Poinsettia Globally
(Euphorbia heterophylla)
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Herbicide Resistant Wild Poinsettia Globally
(Euphorbia heterophylla)
#CountryFirstYearSituationActive IngredientsSite of Action
1 BrazilBrazil 1993 Soybean chlorimuron-ethyl, cloransulam-methyl, imazamox, imazaquin, and imazethapyr 5 ALS inhibitors (B/2)
87Euphorbia heterophyllaWild Poinsettia5294
2 BrazilBrazil 2004 Corn (maize), and Soybean acifluorfen-sodium, cloransulam-methyl, diclosulam, flumetsulam, flumiclorac-pentyl, fomesafen, imazethapyr, lactofen, metsulfuron-methyl, nicosulfuron, and saflufenacil 5 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
PPO inhibitors (E/14)
87Euphorbia heterophyllaWild Poinsettia5215
3 BrazilBrazil 2019 Soybean glyphosate 5 EPSP synthase inhibitors (G/9)
87Euphorbia heterophyllaWild Poinsettia19213
4 EcuadorEcuador 1990 Corn (maize), and Soybean linuron 14 PSII inhibitors - Serine 264 Binders (C2/7)
87Euphorbia heterophyllaWild Poinsettia87
5 ParaguayParaguay 1995 Soybean imazethapyr 46 ALS inhibitors (B/2)
87Euphorbia heterophyllaWild Poinsettia1162
Literature about Similar Cases

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