Herbicide Resistant Weeds

GROUP C2/7 RESISTANT DOWNY BROME (Bromus tectorum)
Spain

Tuesday, February 09, 2010

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Downy Brome

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

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Introduction

Level of Infestation

Downy Brome (Bromus tectorum) is a monocot weed in the Poaceae family. In Spain this weed first evolved resistance to Group C2/7 herbicides in 1990 and infests wheat. Group C2/7 herbicides are known as Ureas and amides (Inhibition of photosynthesis at photosystem II). Research has shown that these particular biotypes are resistant to chlorotoluron and they may be cross-resistant to other Group C2/7 herbicides.

Local weed scientists estimate that Group C2/7 resistant Downy Brome in Spain infests 2-5 sites and the number of sites are decreasing. They also estimate that there are 11-50 acres infested with Group C2/7 resistant Downy Brome and the area infested has stabilized.

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 Nov 18, 2000 )
Common Name	Downy Brome
Species	Bromus tectorum
Group	Ureas and amides (C2/7)
Herbicides	chlorotoluron
Location	Spain
Year	1990
Situation(s)	wheat
Sites	2-5
Acres Infested	11-50
Contributors	Rafael De Prado
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NOTES ABOUT THIS BIOTYPE

AREAS FOUND

Rafael De Prado

Pueblonueuo (Cordoba)

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GENERAL

Rafael De Prado

Enhanced detoxification

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ACADEMIC ASPECTS

Confirmation Tests

Field, Greenhouse, and Laboratory trials comparing a known susceptible Downy Brome biotype with this Downy Brome 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

Studies on the mechanism of resistance of Group C2/7 resistant Downy Brome from Spain indicate that resistance is due to enhanced metabolism. 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 C2/7 resistant Downy Brome from Spain please update the database.

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HERBICIDE RESISTANT DOWNY BROME GLOBALLY
#	Country	Year	Sites	Acres	Mode of Action
1.	France	1981	unknown	unknown	Photosystem II inhibitors (C1/5)
2.	Spain	1990	2-5	11-50	Ureas and amides (C2/7)
3.	Spain	1990	2-5	11-50	Photosystem II inhibitors (C1/5)
4.	USA (Oregon)	1997	2-5	1-5	ALS inhibitors (B/2)
5.	USA (Oregon)	2005	1	11-50	ACCase inhibitors (A/1)

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 Bromus tectorum
Physiological and molecular basis for ALS inhibitor resistance in Bromus tectorum biotypes.
Park, K. W. and C. A. Mallory Smith 2004. Physiological and molecular basis for ALS inhibitor resistance in Bromus tectorum biotypes. Weed Research. 44: 71-77.
Cross-resistance of primisulfuron-resistant Bromus tectorum L. (downy brome) to sulfosulfuron.
Mallory Smith, C., P. Hendrickson, and G. Mueller Warrant. 1999. Cross-resistance of primisulfuron-resistant Bromus tectorum L. (downy brome) to sulfosulfuron. Weed Science. 47: 256-257.

CONTRIBUTING WEED SCIENTISTS

RAFAEL DE PRADO	Edit
Universidad de Cordoba Qvimica Agricola y Edafologa E T S Ingenieros Agronomos Apartado de Correos 3048 Cordoba, E-14080 Spain Email Rafael De Prado Web : Web Site Link

Acknowledgements

Where to now?

The Herbicide Resistance Action Committee, the Weed Science Society of America, and weed scientists in Spain have been instrumental in providing you this information. Particular thanks is given to Rafael De Prado for providing detailed information.

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