INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

MULTIPLE RESISTANT LATE WATERGRASS
(Echinochloa phyllopogon (=E. oryzicola))


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)

Portugal, Ribatejo
INTRODUCTION LATE WATERGRASS
Late Watergrass (Echinochloa phyllopogon (=E. oryzicola)) is a monocot weed in the Poaceae family.  In Portugal this weed first evolved multiple resistance (to 2 herbicide sites of action) in 2020 and infests Rice.  Multiple resistance has evolved to herbicides in the Groups 1 (Legacy A), and Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B).  These particular biotypes are known to have resistance to penoxsulam, and profoxydim and they may be cross-resistant to other herbicides in the Groups 1 (Legacy A), and Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B).

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 May 04, 2024 )

Common NameLate Watergrass
SpeciesEchinochloa phyllopogon (=E. oryzicola)
GroupInhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicidespenoxsulam, and profoxydim
LocationPortugal, Ribatejo
Year2020
Situation(s)Rice
Contributors - (Alphabetically)Isabel Calha 
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory 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, 2 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

Studies on the mechanism of resistance of multiple resistant Late Watergrass from Portugal 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 multiple resistant Late Watergrass from Portugal please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

ISABEL CALHA
Instituto Nacional De Recursos Biológicos, Ip (inrb I.p. )
Laboratório Nacional De Investigação Agrária (linia)
Unidade De Investigação De Protecção De Plantas (uipp)
Dept of Agronomy& Plant Genetics
411 Borlaug Hall, 1991 Upper Buford Circle
Oeiras, 2784-505
Portugal
Email Isabel Calha

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Portugal have been instrumental in providing you this information. Particular thanks is given to Isabel Calha 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
Literature about Similar Cases

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