International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Helianthus annuus)

EPSP synthase inhibitors (G/9)

United States, Texas
Common Sunflower (Helianthus annuus) is a dicot weed in the Asteraceae family.  In Texas this weed first evolved resistance to Group G/9 herbicides in 2015 and infests Corn (maize).   Group G/9 herbicides are known as EPSP synthase inhibitors (Inhibition of EPSP synthase).  Research has shown that these particular biotypes are resistant to glyphosate and they may be cross-resistant to other Group G/9 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.

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QUIK STATS (last updated Feb 09, 2017 )

Common NameCommon Sunflower
SpeciesHelianthus annuus
GroupEPSP synthase inhibitors (G/9)
LocationUnited States, Texas
Situation(s)Corn (maize)
Contributors - (Alphabetically)Muthukumar Bagavathiannan, and Josh McGinty 
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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.

Genetic studies on Group G/9 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 G/9 resistant Common Sunflower from Texas please update the database.
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Graduate Student
The University Of Nottingham
Plant Sciences
College of Natural& Applied Sciences
UOG Station, Western Pacific Tropical Research Center
Loughborough, , LE12 5RD, Leicestershire
United Kingdom
Email Muthukumar Bagavathiannan
Extension Agronomist
Texas A&M Agrilife Extension Service
Soil and Crop Sciences
10345 State Highway 44
Corpus Christi, 78406, Texas
United States
Email Josh McGinty
Web   : Web Site Link


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Texas have been instrumental in providing you this information. Particular thanks is given to Muthukumar Bagavathiannan, and Josh McGinty for providing detailed information.
Herbicide Resistant Common Sunflower Globally
(Helianthus annuus)
Herbicide Resistant Common Sunflower Globally
(Helianthus annuus)
Drag a column header and drop it here to group by that column
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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