International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
GROUP C1/5 RESISTANT RED AMARANTH
(Amaranthus cruentus)


Photosystem II inhibitors (C1/5)

Spain
INTRODUCTION RED AMARANTH
Red Amaranth (Amaranthus cruentus) is a dicot weed in the Amaranthaceae family.  In Spain this weed first evolved resistance to Group C1/5 herbicides in 1989 and infests Corn (maize).   Group C1/5 herbicides are known as Photosystem II inhibitors (Inhibition of photosynthesis at photosystem II).  Research has shown that these particular biotypes are resistant to atrazine and they may be cross-resistant to other Group C1/5 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 NameRed Amaranth
SpeciesAmaranthus cruentus
GroupPhotosystem II inhibitors (C1/5)
Herbicidesatrazine
LocationSpain
Year1989
Situation(s)Corn (maize)
Contributors - (Alphabetically)Rafael De Prado 
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NOTES ABOUT THIS BIOTYPE

GENERAL

Rafael De Prado
Mechanism of resistance is target site.

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ACADEMIC ASPECTS

Confirmation Tests

Field, Greenhouse, and Laboratory trials comparing a known susceptible Red Amaranth biotype with this Red Amaranth 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 C1/5 resistant Red Amaranth 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

Triazine resistant weeds often exhibit a lower relative fitness when compared to susceptible biotypes.  The most common mutation conferring triazine resistance (Ser 264 to Gly mutation of the psbA gene) also causes a reduction in CO2 fixation, quantum yield, and seed and biomass production.  There is no record in this database referring specifically to fitness studies on Group C1/5 resistant Red Amaranth from Spain.
 
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CONTRIBUTING WEED SCIENTISTS

RAFAEL DE PRADO
Universidad De Cordoba
Qvimica Agricola Y Edafologa
E T S Ingenieros Agronomos
PO Box 119
Cordoba, E-14080, Andalusia
Spain
Email Rafael De Prado

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Spain have been instrumental in providing you this information. Particular thanks is given to Rafael De Prado for providing detailed information.
Herbicide Resistant Red Amaranth Globally
(Amaranthus cruentus)
Herbicide Resistant Red Amaranth Globally
(Amaranthus cruentus)
Drag a column header and drop it here to group by that column
Herbicide Resistant Red Amaranth Globally
(Amaranthus cruentus)
#CountryFirstYearSituationActive IngredientsSite of Action
1 SpainSpain 1989 Corn (maize) atrazine 38 Photosystem II inhibitors (C1/5)
11Amaranthus cruentusRed Amaranth176
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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Tuesday, September 17, 2019 .  Available  www.weedscience.org
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