International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Helianthus annuus)

ALS inhibitors (B/2)

United States, Kansas
Common Sunflower (Helianthus annuus) is a dicot weed in the Asteraceae family.  In Kansas this weed first evolved resistance to Group B/2 herbicides in 1996 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 imazethapyr and they may be cross-resistant to other Group B/2 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.

If we do not have a picture for this weed, or you can provide a better picture (scan, digital camera etc) please please e-mail it to us.

QUIK STATS (last updated Jan 01, 2014 )

Common NameCommon Sunflower
SpeciesHelianthus annuus
GroupALS inhibitors (B/2)
LocationUnited States, Kansas
Contributors - (Alphabetically)Kassim Al-Khatib, and Dallas Peterson 
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Kassim Al-Khatib
Eastern Kansas

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Confirmation Tests

Greenhouse, and Laboratory 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.

Genetic studies on Group B/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 B/2 resistant Common Sunflower from Kansas please update the database.
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Director and Ce Specialist, Statewide IPM Program
Statewide IPM Program
Integrated Pest Management
2801 Second Street #152
Davis, 95618-7774, California
United States
Email Kassim Al-Khatib
Web   : Web Site Link
Professor and Extension Weed Specialist
Kansas State University
Department of Agronomy
3703 Throckmorton Plant Sciences Center
1712 Claflin Road
Manhattan, KS 66506-0110, Kansas
United States
Email Dallas Peterson
Web   : Web Site Link


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Kansas have been instrumental in providing you this information. Particular thanks is given to Kassim Al-Khatib, and Dallas Peterson for providing detailed information.
Herbicide Resistant Common Sunflower Globally
(Helianthus annuus)
Herbicide Resistant Common Sunflower Globally
(Helianthus annuus)
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Herbicide Resistant Common Sunflower Globally
(Helianthus annuus)
#CountryFirstYearSituationActive IngredientsSite of Action
1 FranceFrance 2009 Sunflower imazamox, and tribenuron-methyl 17 ALS inhibitors (B/2)
95Helianthus annuusCommon Sunflower9929
2 United States (Kansas) United StatesKansas1996 Soybean imazethapyr 45 ALS inhibitors (B/2)
95Helianthus annuusCommon Sunflower499
3 United States (Missouri) United StatesMissouri1996 Soybean chlorimuron-ethyl, cloransulam-methyl, flumetsulam, halosulfuron-methyl, imazaquin, imazethapyr, and oxasulfuron 45 ALS inhibitors (B/2)
95Helianthus annuusCommon Sunflower1067
4 United States (South Dakota) United StatesSouth Dakota1996 Cropland imazethapyr 45 ALS inhibitors (B/2)
95Helianthus annuusCommon Sunflower1186
5 United States (Iowa) United StatesIowa1997 Corn (maize), and Soybean chlorimuron-ethyl, and imazethapyr 45 ALS inhibitors (B/2)
95Helianthus annuusCommon Sunflower5230
6 United States (Texas) United StatesTexas2015 Corn (maize) glyphosate 45 EPSP synthase inhibitors (G/9)
95Helianthus annuusCommon Sunflower15062
Literature about Similar Cases

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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Saturday, September 21, 2019 .  Available
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