Herbicide Resistant Weeds

GROUP B/2 RESISTANT HAIRY BEGGARTICKS (Bidens pilosa)
Brazil

Saturday, July 31, 2010

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Hairy Beggarticks

1.	Introduction
2.	Level of Infestation
3.	Quick Statistics
4.	Notes about this biotype
5.	Academic Aspects
6.	R Hairy Beggarticks Globally
7.	Fact Sheets and Literature
8.	Contributing Weed Scientists
9.	Acknowledgements
10.	Where to now?

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Introduction

Level of Infestation

Hairy Beggarticks (Bidens pilosa) is a dicot weed in the Asteraceae family. In Brazil this weed first evolved resistance to Group B/2 herbicides in 1993 and infests soybean. Group B/2 herbicides are known as ALS inhibitors (Inhibition of acetolactate synthase ALS (acetohydroxyacid synthase AHAS)). Research has shown that these particular biotypes are resistant to chlorimuron-ethyl, imazaquin, imazethapyr, nicosulfuron, and pyrithiobac-Na and they may be cross-resistant to other Group B/2 herbicides.

Local weed scientists estimate that Group B/2 resistant Hairy Beggarticks in Brazil infests 51-100 sites and the number of sites are increasing. They also estimate that there are 1001-10000 acres infested with Group B/2 resistant Hairy Beggarticks and the area infested is increasing.

The 'Group' letters/numbers that you see throughout this web site refer to the classification of herbicides by their mode of action. To see a full list of herbicides and HRAC herbicide classifications click here.

QUIK STATS ( last updated Dec 07, 2000 )
Common Name	Hairy Beggarticks
Species	Bidens pilosa
Group	ALS inhibitors (B/2)
Herbicides	chlorimuron-ethyl, imazaquin, imazethapyr, nicosulfuron, and pyrithiobac-Na
Location	Brazil, Mato Grosso Do Sul
Year	1993
Situation(s)	soybean
Sites	51-100
Acres Infested	1001-10000
Contributors	Pedro Christoffoleti
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NOTES ABOUT THIS BIOTYPE

GENERAL

Pedro Christoffoleti

The fist site of B. pilosa resistant to ALS inhibitor herbicide was found after 6 applications of imazaquin/chlorimuron in the soybean area. The areas with this weed occurs is a mixture of the species Bidens pilosa and Bidens subalternans. Bioassays and dose response curves has been conducted in the greenhouse conditions as ESALQ/USP - Brazil in Master of Science Dissertation by Patricia A. Monqueiro, adviser by Pedro J. Christoffoleti, and it proved a cross resistance of this biotype to Sulfonilureia, Imidazolinone, Triazolopiirimidina and Pirimidiloxibenzoato. Also some laboratory test has proved that resistance is due to an altered site of the ALS enzyme. The summary of Patrícia's dissertation is as follow: The weeds Bidens pilosa/Bidens subalternans and Amaranthus quitensis are controlled in the soybean crop by herbicides; but the acetolactate synthase (ALS - code EC 4.1.3.18) inhibitor herbicides are the most sprayed by soybean growers. However, the intensive and repetitive use of these herbicides in São Gabriel do Oeste county (MS - Brazil) and in the provinces of Córdoba and Tucumã (Argentina), selected resistant biotypes of these weeds. Therefore, it was developed a research project aiming to study the biology, management and the genetic/biochemical caracterization, using these weed biotypes. From greenhouse experiments dose-response curves and GR50 values were obtained, proving the cross resistance to imidazolinones and sulfonylureas of Bidens pilosa/Bidens subalternans and Amaranthus quitensis. It was also evaluated, under field conditons, the control of the resistant biotype of Bidens pilosa/Bidens subalternans to ALS inhibitor herbicides and alternatives (herbicides with different mechanism of action from ALS inhibition). It was concluded that the herbicide chlorimuron-ethyl and imazethapyr, at reccommended rate did not control the resistant biotype, but the alternative herbicides lactofen, fomesafen and bentazon were efficient. Seeds of Bidens pilosa/Bidens subalternans from plants of the ALS inhibitor herbicides failure in the field experiment and Amaranthus quitensis scapes from Argentina, were collected and used to install experiments in the greennhouse, whete it was tested the same treatements used in the field experiment. The results proved that alternative herbicides, sprayed alone, or in mixture with ALS inhibitor, controlled efficently both resistant and susceptible populations. It was conducted experiments of growth analysis of the resistant and susceptible biotypes of these weeds, in order to compare the competitive ability of the biotypes. According to the results, there is no adaptative cost to the resistant biotype. It was conducted a bioassay, in order to test a rapid detection of resistant biotypes to ALS inhibitor herbicides, spraying at the same time inhibitor herbicides of ALS and KARI (an enzyme that act in the reaction right after the acetolactate formation). The results of the acetolactate accumulation in resistant plants was meassured by the accumulation of acetoin, which concentration was meassured by the color of the solution developed in naphtol and creatine. By this test it was possible to confirm the resistance of the biotypes of Bidens pilosa/Bidens subalternans and Amaranthus quitensis due to an insensitivity of the ALS. The sequencing of the gen that codify the ALS in resistant and susceptible of Amaranthus quitensis, did not show any mutation in the Domain A, suggesting that other possition

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ACADEMIC ASPECTS

Confirmation Tests

Field, 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.

Genetics

Genetic studies on Group B/2 resistant Hairy Beggarticks indicate that inheritance is determined by a , nuclear trait. 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 B/2 resistant Hairy Beggarticks from Brazil 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 B/2 resistant Hairy Beggarticks from Brazil please update the database.

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HERBICIDE RESISTANT HAIRY BEGGARTICKS GLOBALLY
#	Country	Year	Sites	Acres	Mode of Action
1.	Brazil	1993	51-100	1001-10000	ALS inhibitors (B/2)
2.	Kenya	1991	unknown	unknown	Bipyridiliums (D/22)

FACT SHEETS AND OTHER LITERATURE	Format
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Scientific Abstracts on Herbicide Resistant Bidens pilosa
Dose response curves of resistant and susceptible Bidens pilosa to ALS inhibitor herbicides.
Christoffoleti, P. J. and L. Foloni L. 1999. Dose response curves of resistant and susceptible Bidens pilosa to ALS inhibitor herbicides. 1999 Brighton crop protection conference: weeds. Proceedings of an international conference, Brighton, UK, 15-18 November 1999. 1: 159-162.
Herbicide resistant weed problems in developing world and methods to overcome them.
Malik, R. K., H. Brown (ed.), G. W. Cussans (ed.), M. D. Devine (ed.), S. O. Duke (ed.), C. Fernandez Quintanilla (ed.), A. Helweg (ed.), R. E. Labrada (ed.), M. Landes (ed.), P. Kudsk (ed.), and J. C. Streibig. 1996. Herbicide resistant weed problems in developing world and methods to overcome them. Proceedings of the second international weed control congress, Copenhagen, Denmark, 25-28 June 1996. 1-4: 665-673.
Tolerance of Bidens pilosa L and Parthenium hysterophorus L to paraquat (Gramoxone) in Kenya coffee.
Njoroge, J. M. 1991. Tolerance of Bidens pilosa L and Parthenium hysterophorus L to paraquat (Gramoxone) in Kenya coffee. Kenya Coffee. 56: 999-1001.

CONTRIBUTING WEED SCIENTISTS

PEDRO CHRISTOFFOLETI	Edit
Associate Professor Universidade de Sao Paulo Dept. de Produção Vegetal ESALQ/USP C. POSTAL 09 Piracicaba, 13418-900, São Paulo Brazil Email Pedro Christoffoleti

Acknowledgements

Where to now?

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 Pedro Christoffoleti for providing detailed information.

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