International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
GROUP C1/5 RESISTANT FALL PANICUM
(Panicum dichotomiflorum)


Photosystem II inhibitors (C1/5)

Spain
INTRODUCTION FALL PANICUM
Fall Panicum (Panicum dichotomiflorum) is a monocot weed in the Poaceae family.  In Spain this weed first evolved resistance to Group C1/5 herbicides in 1981 and infests Corn (maize), and Cropland.   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 Nov 19, 2000 )

Common NameFall Panicum
SpeciesPanicum dichotomiflorum
GroupPhotosystem II inhibitors (C1/5)
Herbicidesatrazine
LocationSpain
Year1981
Situation(s)Corn (maize), and Cropland
Contributors - (Alphabetically)Rafael De Prado 
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NOTES ABOUT THIS BIOTYPE

GENERAL

Rafael De Prado
Romera, E. //Valenzuela, A. //Menendez, J. //De Prado, R. , 1983. Atrazine-resistance mechanisms in Panicum dichotomiflorum and Polygonum lapathifolium.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Fall Panicum biotype with this Fall Panicum 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 Fall Panicum 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 Fall Panicum from Spain indicate that resistance is due to enhanced metabolism.  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 Fall Panicum 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 Fall Panicum Globally
(Panicum dichotomiflorum)
Herbicide Resistant Fall Panicum Globally
(Panicum dichotomiflorum)
Drag a column header and drop it here to group by that column
Herbicide Resistant Fall Panicum Globally
(Panicum dichotomiflorum)
#CountryFirstYearSituationActive IngredientsSite of Action
1 SpainSpain 1981 Corn (maize), and Cropland atrazine 38 Photosystem II inhibitors (C1/5)
122Panicum dichotomiflorumFall Panicum527
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