International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
GROUP B/2 RESISTANT MARSHELDER
(Iva xanthifolia)


ALS inhibitors (B/2)

United States, North Dakota
INTRODUCTION MARSHELDER
Marshelder (Iva xanthifolia) is a dicot weed in the Asteraceae family.  In North Dakota this weed first evolved resistance to Group B/2 herbicides in 2003 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 imazamox, and tribenuron-methyl 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 Feb 01, 2005 )

Common NameMarshelder
SpeciesIva xanthifolia
GroupALS inhibitors (B/2)
Herbicidesimazamox, and tribenuron-methyl
LocationUnited States, North Dakota
Year2003
Situation(s)Soybean
Contributors - (Alphabetically)Kirk Howatt 
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Marshelder biotype with this Marshelder 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 Marshelder 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 Marshelder from North Dakota please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

KIRK HOWATT
Associate Professor
North Dakota State University
Department of Plant Sciences
Loftsgard Hall 470F
Fargo, 58108-6050, North Dakota
United States
Email Kirk Howatt
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in North Dakota have been instrumental in providing you this information. Particular thanks is given to Kirk Howatt for providing detailed information.
Herbicide Resistant Marshelder Globally
(Iva xanthifolia)
Herbicide Resistant Marshelder Globally
(Iva xanthifolia)
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Herbicide Resistant Marshelder Globally
(Iva xanthifolia)
#CountryFirstYearSituationActive IngredientsSite of Action
1 United States (North Dakota) United StatesNorth Dakota2003 Soybean imazamox, and tribenuron-methyl 45 ALS inhibitors (B/2)
229Iva xanthifoliaMarshelder5236
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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Tuesday, December 10, 2019 .  Available  www.weedscience.org
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