International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
GROUP C1/5 RESISTANT TUMBLE PIGWEED
(Amaranthus albus)


Photosystem II inhibitors (C1/5)

Spain
INTRODUCTION TUMBLE PIGWEED
Tumble Pigweed (Amaranthus albus) is a dicot weed in the Amaranthaceae family.  In Spain this weed first evolved resistance to Group C1/5 herbicides in 1987 and infests Orchards.   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 simazine 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 Nov 18, 2000 )

Common NameTumble Pigweed
SpeciesAmaranthus albus
GroupPhotosystem II inhibitors (C1/5)
Herbicidessimazine
LocationSpain
Year1987
Situation(s)Orchards
Contributors - (Alphabetically)Rafael De Prado 
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NOTES ABOUT THIS BIOTYPE

AREAS FOUND

Rafael De Prado
Cordoba, Jaen.

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GENERAL

Rafael De Prado
Target site mechanism of resistance.

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ACADEMIC ASPECTS

Confirmation Tests

Field, Greenhouse, and Laboratory trials comparing a known susceptible Tumble Pigweed biotype with this Tumble Pigweed 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 Tumble Pigweed 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 Group C1/5 resistant Tumble Pigweed from Spain 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

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 Tumble Pigweed 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 Tumble Pigweed Globally
(Amaranthus albus)
Herbicide Resistant Tumble Pigweed Globally
(Amaranthus albus)
Drag a column header and drop it here to group by that column
Herbicide Resistant Tumble Pigweed Globally
(Amaranthus albus)
#CountryFirstYearSituationActive IngredientsSite of Action
1 SpainSpain 1987 Orchards simazine 38 Photosystem II inhibitors (C1/5)
7Amaranthus albusTumble Pigweed182
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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Monday, September 16, 2019 .  Available  www.weedscience.org
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