Herbicide Resistant Weeds

GROUP B/2 RESISTANT RAGWEED PARTHENIUM (Parthenium hysterophorus)
Brazil

Saturday, July 31, 2010

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Ragweed Parthenium

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

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Introduction

Level of Infestation

Ragweed Parthenium (Parthenium hysterophorus) is a dicot weed in the Asteraceae family. In Brazil this weed first evolved resistance to Group B/2 herbicides in 2004 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, cloransulam-methyl, foramsulfuron, imazethapyr, and iodosulfuron-methyl-sodium and they may be cross-resistant to other Group B/2 herbicides.

Local weed scientists estimate that Group B/2 resistant Ragweed Parthenium in Brazil infests 11-50 sites and the number of sites are increasing. They also estimate that there are 101-500 acres infested with Group B/2 resistant Ragweed Parthenium 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 Feb 04, 2005 )
Common Name	Ragweed Parthenium
Species	Parthenium hysterophorus
Group	ALS inhibitors (B/2)
Herbicides	chlorimuron-ethyl, cloransulam-methyl, foramsulfuron, imazethapyr, and iodosulfuron-methyl-sodium
Location	Brazil, PARANÀ
Year	2004
Situation(s)	soybean
Sites	11-50
Acres Infested	101-500
Contributors	Dioniso Gazziero
Input Data	Edit this Case \| Add New Case of Resistance \| Add Note

ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Ragweed Parthenium biotype with this Ragweed Parthenium 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

The genetic basis of resistance for this biotype is either unknown or has not been entered in the database. If you know anything about the genetic inheritance of this biotype please update the database.

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

Researchers have indicated that Group B/2 resistant Ragweed Parthenium is ecologically less fit than normal susceptible Ragweed Parthenium. There may be a note below or an article discussing the fitness of this biotype in the "Fact Sheets and Other Literature"

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HERBICIDE RESISTANT RAGWEED PARTHENIUM GLOBALLY
#	Country	Year	Sites	Acres	Mode of Action
1.	Brazil	2004	11-50	101-500	ALS inhibitors (B/2)
2.	Colombia	2004	2-5	51-100	Glycines (G/9)

FACT SHEETS AND OTHER LITERATURE	Format
At Present there are no articles on this case of resistance. Please help by adding an article.
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Scientific Abstracts on Herbicide Resistant Parthenium hysterophorus
Weeds resistant to chlorsulfuron and atrazine from the north-east grain region of Australia.
Adkins, S. W., D. Wills, M. Boersma, S. R. Walker, G. Robinson, R. J. McLeod, and J. P. Einam. 1997. Weeds resistant to chlorsulfuron and atrazine from the north-east grain region of Australia. Weed Research. 37: 343-349.
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

DIONISO GAZZIERO	Edit
RESISTENCIA DE PLANTAS DANINHAS:CLASSIFICAÇAO DOS HERBICIDAS Embrapa-Soja Agronomist Caixa Postal 231 Londrina, 86001-970, Parana Brazil Email Dioniso Gazziero

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 Dioniso Gazziero for providing detailed information.

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