International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Euphorbia heterophylla)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

Paraguay, Itapua
Wild Poinsettia (Euphorbia heterophylla) is a dicot weed in the Euphorbiaceae family.  In Paraguay this weed first evolved resistance to Group 2 (Legacy B) herbicides in 1995 and infests Soybean.   Group 2 (Legacy B) herbicides are known as Inhibition of Acetolactate Synthase (Inhibition of Acetolactate Synthase ).  Research has shown that these particular biotypes are resistant to imazethapyr and they may be cross-resistant to other Group 2 (Legacy B) 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.

If we do not have a picture for this weed, or you can provide a better picture (scan, digital camera etc) please please e-mail it to us.

QUIK STATS (last updated Sep 15, 2000 )

Common NameWild Poinsettia
SpeciesEuphorbia heterophylla
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
LocationParaguay, Itapua
Contributors - (Alphabetically)Adolfo Benegas 
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Adolfo Benegas
Cost before = $20 per acre. Cost after =$40-80.

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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 HRAC Group 2 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 2 (Legacy B) resistant Wild Poinsettia from Paraguay please update the database.
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Dale Bumpers National Rice Research Center
2890 Hwy 130 East,
Encarnacion, Itapua
Email Adolfo Benegas


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Paraguay have been instrumental in providing you this information. Particular thanks is given to Adolfo Benegas 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 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
87Euphorbia heterophyllaWild Poinsettia5294
2 BrazilBrazil 2004 Corn (maize), and Soybean acifluorfen, cloransulam-methyl, diclosulam, flumetsulam, flumiclorac-pentyl, fomesafen, imazethapyr, lactofen, metsulfuron-methyl, nicosulfuron, and saflufenacil 5 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
87Euphorbia heterophyllaWild Poinsettia5215
3 BrazilBrazil 2019 Soybean glyphosate 5 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
87Euphorbia heterophyllaWild Poinsettia19213
4 EcuadorEcuador 1990 Corn (maize), and Soybean linuron 14 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
87Euphorbia heterophyllaWild Poinsettia87
5 ParaguayParaguay 1995 Soybean imazethapyr 46 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
87Euphorbia heterophyllaWild Poinsettia1162
Literature about Similar Cases

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