International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Bidens pilosa)

Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2)

Brazil, Paraná
Hairy Beggarticks (Bidens pilosa) is a dicot weed in the Asteraceae family.  In Brazil this weed first evolved multiple resistance (to 2 herbicide sites of action) in 2016 and infests Corn (maize), and Soybean.  Multiple resistance has evolved to herbicides in the Groups 2 (Legacy B), and PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2).  These particular biotypes are known to have resistance to atrazine, and imazethapyr and they may be cross-resistant to other herbicides in the Groups 2 (Legacy B), and PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2).

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 Nov 02, 2016 )

Common NameHairy Beggarticks
SpeciesBidens pilosa
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

PSII inhibitors - Serine 264 Binders HRAC Group 5 (Legacy C1 C2)
Herbicidesatrazine, and imazethapyr
LocationBrazil, Paraná
Situation(s)Corn (maize), and Soybean
Contributors - (Alphabetically)Nilda R. Burgos, Jamil Constantin, Rubem Oliveira, and Hudson Takano 
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Rubem Oliveira

Ciência e Agrotecnologia 40(5):547-554, Sep/Oct. 2016

Multiple resistance to atrazine and imazethapyr in hairy beggarticks (Bidens pilosa)

Resistência múltipla a atrazina e imazethapyr em picão-preto (Bidens pilosa)

Hudson Kagueyama Takano1*, Rubem Silvério de Oliveira Junior1, Jamil Constantin1 Guilherme Braga Pereira Braz1, Luiz Henrique Morais Franchini1, Nilda Roma Burgos2

1Universidade Estadual de Maringá/UEM, Maringá, PR, Brasil 2University of Arkansas - Fayetteville, Arkansas, USA *Corresponding author: Received in May 30, 2016 and approved in July 29, 2016

  ABSTRACT Resistance to herbicides is a serious threat to crop production worldwide, especially in agronomic crops and cereals. This research evaluated the possible occurrence of Bidens pilosa resistant to imazethapyr and atrazine in Brazil. The resistant biotype was collected from an area with a history of repeated application of photosystem II (PSII) and ALS inhibitor herbicides. The susceptible biotype was collected from an area with no history of herbicide application. Resistance verification experiments were carried out in the greenhouse. The treatments were arranged in a 3 x 8 factorial scheme, where the first factor was populations [susceptible (S), parent resistant (PR), and resistant F1 (RF1)]; and the second factor was herbicide dose (0, 375, 750, 1500, 3000, 6000, 12000 and 24000 g ha-1 for atrazine; or 0, 12.5, 25, 50, 100, 200, 400 and 800 g ha-1 for imazethapyr). The resistance factor to atrazine was 2.83 for PR and 5.55 for RF1. This population was more resistant to imazethapyr (>21-fold) than it was to atrazine. The recommended maximum dose of the herbicides did not control this B. pilosa population adequately. The data support the claim that B. pilosa population from this field in Quarto Centenário, Parana is resistant to two herbicide modes of action - PSII inhibitor (i.e. atrazine) and ALS inhibitor (i.e. imazethapyr). This is the first report of such case for this species, globally. Cross-resistance to other ALS inhibitors and other PS II inhibitors as well as the respective mechanisms of resistance to each herbicide are being investigated.

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Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Hairy Beggarticks biotype with this Hairy Beggarticks 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, 5 resistant Hairy Beggarticks 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 multiple resistant Hairy Beggarticks from Brazil please update the database.
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Professor - Weed Physiology
University Of Arkansas, Fayetteville
Crop, Soil
And Environmental Sciences
1366 W. Altheimer Dr.
Fayetteville, 72704, Arkansas
United States
Email Nilda R. Burgos
Web   : Web Site Link
Associate Professor
Universidade Estadual de Maringá
Departamento de Agronomia
Av. Colombo
Maringá, PR, 87020-900, Paraná
Email Jamil Constantin
Web   : Web Site Link
Associate Professor
Universidade Estadual De Maringá - Departamento De Agronomia
Núcleo De Estudos Avançados Em Ciência Das Plantas Daninhas
Av. Colombo 5790
Maringá, 87020-900, Paraná
Email Rubem Oliveira
Web   : Web Site Link
Graduate Student
Colorado State University
Bioagricultural Sciences and Pest Management
300 W Pitkin St
Fort Collins, 80521, Colorado
United States
Email Hudson Takano
Web   : Web Site Link


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Brazil have been instrumental in providing you this information. Particular thanks is given to Nilda R. Burgos, Jamil Constantin, Rubem Oliveira, and Hudson Takano for providing detailed information.
Herbicide Resistant Hairy Beggarticks Globally
(Bidens pilosa)
Herbicide Resistant Hairy Beggarticks Globally
(Bidens pilosa)
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Herbicide Resistant Hairy Beggarticks Globally
(Bidens pilosa)
#CountryFirstYearSituationActive IngredientsSite of Action
1 BrazilBrazil 1993 Soybean chlorimuron-ethyl, imazaquin, imazethapyr, nicosulfuron, and pyrithiobac-sodium 5 Inhibition of Acetolactate Synthase (B/2)
32Bidens pilosaHairy Beggarticks42
2 BrazilBrazil 2016 Corn (maize), and Soybean atrazine, and imazethapyr 5 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase (B/2)
PSII inhibitors - Serine 264 Binders (C1 C2/5)
32Bidens pilosaHairy Beggarticks14053
3 KenyaKenya 1991 Coffee paraquat 26 PS I Electron Diversion (D/22)
32Bidens pilosaHairy Beggarticks381
4 MexicoMexico 2014 Lime, and sour glyphosate 29 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase (G/9)
32Bidens pilosaHairy Beggarticks9923
Literature about Similar Cases

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