INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 1 (LEGACY A) RESISTANT LATE WATERGRASS
(Echinochloa phyllopogon (=E. oryzicola))


Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)

United States, California
INTRODUCTION LATE WATERGRASS
Late Watergrass (Echinochloa phyllopogon (=E. oryzicola)) is a monocot weed in the Poaceae family.  In California this weed first evolved resistance to Group 1 (Legacy A) herbicides in 1998 and infests Rice.   Group 1 (Legacy A) herbicides are known as Inhibition of Acetyl CoA Carboxylase (Inhibition of Acetyl CoA Carboxylase ).  Research has shown that these particular biotypes are resistant to fenoxaprop-ethyl and they may be cross-resistant to other Group 1 (Legacy A) 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 Sep 15, 2000 )

Common NameLate Watergrass
SpeciesEchinochloa phyllopogon (=E. oryzicola)
GroupInhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
Herbicidesfenoxaprop-ethyl
LocationUnited States, California
Year1998
Situation(s)Rice
Contributors - (Alphabetically)Albert Fischer 
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NOTES ABOUT THIS BIOTYPE

GENERAL

Albert Fischer
Herbicide-resistant watergrass (Echinochloa phyllopogon (Stapf) Koss.) in rice in California. A.J. Fischer*, J.E. Hill, J.F. Williams, J. Anstey, K.M. Jahnes, and C. Ateh, University of California, Davis. Abstract: Accessions of watergrass were collected from selected sites throughout rice growing areas in California following reports of herbicide failure. Plants were grown in the greenhouse and treated with 0.17 kg ai/ha fenoxaprop, 4.5 kg/ha thiobencarb, 4.5 kg/ha propanil, 4.5 kg/ha molinate, and 37 g/ha V-10029 (Valent USA Corp.). Fifteen days after treatment the range of growth (fresh weight as percent of the untreated check) for each herbicide in surviving plants was: fenoxaprop 13-70%, thiobencarb 46-86%, propanil 10-21%, molinate 19-80%, and V-10029 13-63%. Several accession survived treatment (regrowth>20%)with more than one herbicide, including chemicals with different mechanisms of action. A dose-response experiment with one such accession showed the following R/S ratios : fenoxaprop 22, thiobencarb 10, molinate 2, V-10029 2, and propanil 2. Fourtimes the normal rate of fenoxaprop or thiobencarb failed to control this accession. Thus the repeated use of the few available grass hebicides in the predominantly monocultured rice of California may have selected for multiple resistance in late watergrass.

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GENERAL

Albert Fischer
Also resistant to thiobencarb.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Late Watergrass biotype with this Late Watergrass 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 1 resistant Late Watergrass 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 1 (Legacy A) resistant Late Watergrass from California please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

ALBERT FISCHER
Professor
University Of California
Department of Plant Sciences
Weed Ecophysiology
Mail Stop #4 279/279A Robbins Hall
Davis, 95616, California
United States
Email Albert Fischer
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 Albert Fischer for providing detailed information.
Herbicide Resistant Late Watergrass Globally
(Echinochloa phyllopogon (=E. oryzicola))
Herbicide Resistant Late Watergrass Globally
(Echinochloa phyllopogon (=E. oryzicola))
Drag a column header and drop it here to group by that column
Herbicide Resistant Late Watergrass Globally
(Echinochloa phyllopogon (=E. oryzicola))
#CountryFirstYearSituationActive IngredientsSite of Action
1 ChinaChina 2023 Rice penoxsulam 9 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
178Echinochloa phyllopogon (=E. oryzicola)Late Watergrass27267
2 FranceFrance 2013 Rice penoxsulam 17 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
178Echinochloa phyllopogon (=E. oryzicola)Late Watergrass9935
3 GreeceGreece 2009 Rice bispyribac-sodium, foramsulfuron, imazamox, nicosulfuron, penoxsulam, and rimsulfuron 19 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
178Echinochloa phyllopogon (=E. oryzicola)Late Watergrass13052
4 PortugalPortugal 2015 Rice penoxsulam 34 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
178Echinochloa phyllopogon (=E. oryzicola)Late Watergrass27294
5 PortugalPortugal 2020 Rice profoxydim 34 Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
178Echinochloa phyllopogon (=E. oryzicola)Late Watergrass28268
6 PortugalPortugal 2020 Rice penoxsulam, and profoxydim 34 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
178Echinochloa phyllopogon (=E. oryzicola)Late Watergrass28269
7 South KoreaSouth Korea 2006 Rice azimsulfuron, bensulfuron-methyl, bispyribac-sodium, cyhalofop-butyl, fenoxaprop-ethyl, halosulfuron-methyl, imazosulfuron, metamifop, pyrazosulfuron-ethyl, pyribenzoxim, and pyriminobac-methyl 27 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
178Echinochloa phyllopogon (=E. oryzicola)Late Watergrass5392
8 United States (California) United StatesCalifornia1998 Rice fenoxaprop-ethyl 45 Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
178Echinochloa phyllopogon (=E. oryzicola)Late Watergrass283
9 United States (California) United StatesCalifornia1998 Rice thiobencarb/benthiocarb 45 Very Long-Chain Fatty Acid Synthesis inhibitors ( HRAC Group 15 (Legacy K3 N)
178Echinochloa phyllopogon (=E. oryzicola)Late Watergrass1035
10 United States (California) United StatesCalifornia2000 Rice cyhalofop-butyl, fenoxaprop-ethyl, molinate, and thiobencarb/benthiocarb 45 Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
Very Long-Chain Fatty Acid Synthesis inhibitors ( HRAC Group 15 (Legacy K3 N)
178Echinochloa phyllopogon (=E. oryzicola)Late Watergrass5137
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