International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Rottboellia cochinchinensis (=R. exaltata))

ACCase inhibitors (A/1)

United States, Louisiana
Itchgrass (Rottboellia cochinchinensis (=R. exaltata)) is a monocot weed in the Poaceae family.  In Louisiana this weed first evolved resistance to Group A/1 herbicides in 1997 and infests Soybean.   Group A/1 herbicides are known as ACCase inhibitors (Inhibition of acetyl CoA carboxylase (ACCase)).  Research has shown that these particular biotypes are resistant to fluazifop-P-butyl and they may be cross-resistant to other Group A/1 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 Jun 06, 2000 )

Common NameItchgrass
SpeciesRottboellia cochinchinensis (=R. exaltata)
GroupACCase inhibitors (A/1)
LocationUnited States, Louisiana
Contributors - (Alphabetically)Dearl Sanders 
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Dearl Sanders
Point Coupee Parish County

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Confirmation Tests

Field trials comparing a known susceptible Itchgrass biotype with this Itchgrass 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 A/1 resistant Itchgrass 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 A/1 resistant Itchgrass from Louisiana please update the database.
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Professor & Coordinator
Louisiana State University
Cooperative Extension
4419 Idlewild Rd
Clinton, 70722, Louisiana
United States
Email Dearl Sanders
Web   : Web Site Link


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Louisiana have been instrumental in providing you this information. Particular thanks is given to Dearl Sanders for providing detailed information.
Herbicide Resistant Itchgrass Globally
(Rottboellia cochinchinensis (=R. exaltata))
Herbicide Resistant Itchgrass Globally
(Rottboellia cochinchinensis (=R. exaltata))
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Herbicide Resistant Itchgrass Globally
(Rottboellia cochinchinensis (=R. exaltata))
#CountryFirstYearSituationActive IngredientsSite of Action
1 United States (Louisiana) United StatesLouisiana1997 Soybean fluazifop-P-butyl 45 ACCase inhibitors (A/1)
265Rottboellia cochinchinensis (=R. exaltata)Itchgrass1182
2 VenezuelaVenezuela 2004 Corn (maize) foramsulfuron, iodosulfuron-methyl-sodium, and nicosulfuron 80 ALS inhibitors (B/2)
265Rottboellia cochinchinensis (=R. exaltata)Itchgrass5566
Literature about Similar Cases

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