International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
HRAC GROUP 2 (LEGACY B) RESISTANT REDSTEM
(Ammannia coccinea)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

United States, California
INTRODUCTION REDSTEM
Redstem (Ammannia coccinea) is a dicot weed in the Lythraceae family.  In California this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2000 and infests Rice.   Group 2 (Legacy B) herbicides are known as Inhibition of Acetolactate Synthase (Inhibition of Acetolactate Synthase ).  Research has shown that these particular biotypes are resistant to bensulfuron-methyl and they may be cross-resistant to other Group 2 (Legacy B) 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 14, 2003 )

Common NameRedstem
SpeciesAmmannia coccinea
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicidesbensulfuron-methyl
LocationUnited States, California
Year2000
Situation(s)Rice
Contributors - (Alphabetically)Jim Hill 
Edit this Case  |  Add New Case of Resistance  |  Add Note

ACADEMIC ASPECTS

Confirmation Tests

Field, and Greenhouse trials comparing a known susceptible Redstem biotype with this Redstem 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 HRAC Group 2 resistant Redstem 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 2 (Legacy B) resistant Redstem from California please update the database.
 
Edit Case  |  Add Note  |  Add Article  |  Add New Case  |  Help

CONTRIBUTING WEED SCIENTISTS

JIM HILL
CE Specialist
University Of California
Agriculture and Natural Resources
One Shields Avenue
177 Hunt Hall
Davis, 95616, California
United States
Email Jim Hill
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in California have been instrumental in providing you this information. Particular thanks is given to Jim Hill for providing detailed information.
Herbicide Resistant Redstem Globally
(Ammannia coccinea)
Herbicide Resistant Redstem Globally
(Ammannia coccinea)
Drag a column header and drop it here to group by that column
Herbicide Resistant Redstem Globally
(Ammannia coccinea)
#CountryFirstYearSituationActive IngredientsSite of Action
1 JapanJapan 2004 Rice bensulfuron-methyl 25 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
 		209Ammannia coccineaRedstem7791
2 United States (California) United StatesCalifornia2000 Rice bensulfuron-methyl 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
 		209Ammannia coccineaRedstem5135
Literature about Similar Cases

1
Page size:
select
Page: of 0
Items 0 to 0 of 0

1
Page size:
select
Page: of 0
Items 0 to 0 of 0
PERMISSION MUST BE OBTAINED FIRST if you intend to base a significant portion of a scientific paper on data derived from this site.
Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Friday, October 31, 2025 .  Available  www.weedscience.org
Copyright © 1993- 2025 WeedScience.org All rights reserved. Fair use of this material is encouraged. Proper citation is requested.