<b>HRAC Group 2</b> <font size='2'> (Legacy B) </font> resistant Helianthus annuus from United States, Missouri

INTRODUCTION		COMMON SUNFLOWER
Common Sunflower (Helianthus annuus) is a dicot weed in the Asteraceae family. In Missouri this weed first evolved resistance to Group 2 (Legacy B) herbicides in 1996 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 chlorimuron-ethyl, cloransulam-methyl, flumetsulam, halosulfuron-methyl, imazaquin, imazethapyr, and oxasulfuron 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.

QUIK STATS (last updated Sep 15, 2000 )
Common Name	Common Sunflower
Species	Helianthus annuus
Group	Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicides	chlorimuron-ethyl, cloransulam-methyl, flumetsulam, halosulfuron-methyl, imazaquin, imazethapyr, and oxasulfuron
Location	United States, Missouri
Year	1996
Situation(s)	Soybean
Contributors - (Alphabetically)	William Johnson, Andy Kendig, and Reid Smeda
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NOTES ABOUT THIS BIOTYPE

AREAS FOUND

Reid Smeda

Carroll and Ray, Atchison counties. River bottom areas. northwest, west central, and central Missouri.

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CONTROL STRATEGIES

Reid Smeda

Roundup ready beans, atrazine in corn. Remains susceptible to bentazon, lactofen, dicamba, atrazine, glyphosate, glufosinate.

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ACADEMIC ASPECTS

Confirmation Tests

Field, and Greenhouse trials comparing a known susceptible Common Sunflower biotype with this Common Sunflower 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 HRAC Group 2 resistant Common Sunflower 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 Common Sunflower from Missouri please update the database.

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CONTRIBUTING WEED SCIENTISTS

WILLIAM JOHNSON

Associate Professor of Weed Science Purdue University Botany And Plant Pathology Lilly Hall 915 West State Street West Lafayette, 47907-2054, Indiana United States Email William Johnson Web : Web Site Link

ANDY KENDIG

Associate Professor of Weed Science University Of Missouri Botany And Plant Pathology Lilly Hall 14901 Asgrow Rd Portageville, 63873, Missouri United States Email Andy Kendig Web : Web Site Link

REID SMEDA

Assistant Professor - Weed Physiologist University Of Missouri-Columbia Agronomy 219 Redfield Dr Columbia, 65211, Missouri United States Email Reid Smeda Web : Web Site Link

ACKNOWLEDGEMENTS
The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Missouri have been instrumental in providing you this information. Particular thanks is given to William Johnson, Andy Kendig, and Reid Smeda for providing detailed information.

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Herbicide Resistant Common Sunflower Globally
(Helianthus annuus)

#

Country

FirstYear

Situation

Active Ingredients

Site of Action

1

France

2009

Sunflower

imazamox, and tribenuron-methyl