International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
GROUP B/2 RESISTANT GIANT RAGWEED
(Ambrosia trifida)


ALS inhibitors (B/2)

United States, Illinois
INTRODUCTION GIANT RAGWEED
Giant Ragweed (Ambrosia trifida) is a dicot weed in the Asteraceae family.  In Illinois this weed first evolved resistance to Group B/2 herbicides in 1998 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 cloransulam-methyl, and 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.

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QUIK STATS (last updated Jan 22, 2014 )

Common NameGiant Ragweed
SpeciesAmbrosia trifida
GroupALS inhibitors (B/2)
Herbicidescloransulam-methyl, and imazethapyr
LocationUnited States, Illinois
Year1998
Situation(s)Soybean
Contributors - (Alphabetically)Patrick Tranel 
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NOTES ABOUT THIS BIOTYPE

AREAS FOUND

Paul Schmitzer
Carmi, IL; Mt. Carmel, IL

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GENERAL

Paul Schmitzer
During the 1998 introduction of FirstRate herbicide (active ingredient cloransulam-methyl), isolated fields were identified with unexpectedly poor control of common and giant ragweed (Ambrosia artemisiifolia and Ambrosia trifida, respectively) biotypes. Seed heads were collected in the fall of 1998 from selected fields, and plants were reared in the greenhouse. Plants which survived an application of cloransulam-methyl were assayed for ALS inhibition to cloransulam-methyl and other ALS inhibiting herbicide actives. Common ragweed from 20 sites and giant ragweed from 12 sites across the Midwest were found to be resistant to cloransulam-methyl. Some ALS samples extracted from plants which were resistant to cloransulam-methyl were also assayed for resistance to an imidazolinone and sulfonylurea herbicide. These samples represented about a third of the samples which were resistant to cloransulam-methyl and from each of the general geographic areas. In all of the samples assayed for cross resistance, resistance (approximately 1000-fold) was identified to all 3 chemistries. The molecular basis of this resistance has not been determined. No data is available to estimate the total number of acres affected by resistant ragweed since the samples analyzed were primarily from poor performance areas.

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ACADEMIC ASPECTS

Confirmation Tests

Field, Greenhouse, and Laboratory trials comparing a known susceptible Giant Ragweed biotype with this Giant Ragweed 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 Group B/2 resistant Giant Ragweed 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

Studies on the mechanism of resistance of Group B/2 resistant Giant Ragweed from Illinois indicate that resistance is due to an altered target site.  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 B/2 resistant Giant Ragweed from Illinois please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

PATRICK TRANEL
Professor
University Of Illinois
Dept. Of Crop Sciences
1201 W. Gregory Dr.
Urbana, 61801, Illinois
United States
Email Patrick Tranel
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Illinois have been instrumental in providing you this information. Particular thanks is given to Patrick Tranel for providing detailed information.
Herbicide Resistant Giant Ragweed Globally
(Ambrosia trifida)
Herbicide Resistant Giant Ragweed Globally
(Ambrosia trifida)
Drag a column header and drop it here to group by that column
Herbicide Resistant Giant Ragweed Globally
(Ambrosia trifida)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Canada (Ontario) CanadaOntario2008 Soybean glyphosate 7 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5483
2 Canada (Ontario) CanadaOntario2011 Soybean cloransulam-methyl, and glyphosate 7 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed7833
3 United States (Indiana) United StatesIndiana1998 Soybean cloransulam-methyl, and imazethapyr 45 ALS inhibitors (B/2)
184Ambrosia trifidaGiant Ragweed1123
4 United States (Illinois) United StatesIllinois1998 Soybean cloransulam-methyl, and imazethapyr 45 ALS inhibitors (B/2)
184Ambrosia trifidaGiant Ragweed1124
5 United States (Ohio) United StatesOhio1998 Soybean chlorimuron-ethyl, cloransulam-methyl, imazamox, imazaquin, primisulfuron-methyl, and prosulfuron 45 ALS inhibitors (B/2)
184Ambrosia trifidaGiant Ragweed1164
6 United States (Iowa) United StatesIowa2000 Corn (maize), and Soybean cloransulam-methyl, primisulfuron-methyl, and prosulfuron 45 ALS inhibitors (B/2)
184Ambrosia trifidaGiant Ragweed5231
7 United States (Ohio) United StatesOhio2004 Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5278
8 United States (Indiana) United StatesIndiana2005 Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5279
9 United States (Arkansas) United StatesArkansas2005 Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5345
10 United States (Kentucky) United StatesKentucky2005 Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed7878
11 United States (Kansas) United StatesKansas2006 Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5304
12 United States (Minnesota) United StatesMinnesota2006 Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5333
13 United States (Ohio) United StatesOhio2006 Soybean chlorimuron-ethyl, cloransulam-methyl, and glyphosate 45 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5408
14 United States (Tennessee) United StatesTennessee2007 Cotton, and Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5335
15 United States (Minnesota) United StatesMinnesota2008 Soybean cloransulam-methyl, and glyphosate 45 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5508
16 United States (Iowa) United StatesIowa2009 Corn (maize), and Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5463
17 United States (Missouri) United StatesMissouri2009 Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5466
18 United States (Mississippi) United StatesMississippi2010 Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5504
19 United States (Nebraska) United StatesNebraska2010 Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5573
20 United States (Wisconsin) United StatesWisconsin2011 Corn (maize), and Soybean glyphosate 45 EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed5660
21 United States (Missouri) United StatesMissouri2011 Corn (maize) chlorimuron-ethyl, cloransulam-methyl, and glyphosate 45 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
EPSP synthase inhibitors (G/9)
184Ambrosia trifidaGiant Ragweed7808
22 United States (Wisconsin) United StatesWisconsin2013 Soybean cloransulam-methyl, and imazamox 45 ALS inhibitors (B/2)
184Ambrosia trifidaGiant Ragweed7822
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