International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
GROUP C1/5 RESISTANT SQUIRRELTAIL FESCUE
(Vulpia bromoides)


Photosystem II inhibitors (C1/5)

Australia, Western Australia
INTRODUCTION SQUIRRELTAIL FESCUE
Squirreltail Fescue (Vulpia bromoides) is a monocot weed in the Poaceae family.  In Western Australia this weed first evolved resistance to Group C1/5 herbicides in 2014 and infests Pastures.   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 Feb 06, 2016 )

Common NameSquirreltail Fescue
SpeciesVulpia bromoides
GroupPhotosystem II inhibitors (C1/5)
Herbicidessimazine
LocationAustralia, Western Australia
Year2014
Situation(s)Pastures
Contributors - (Alphabetically)Michael Ashworth, and Stephen Powles 
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Squirreltail Fescue biotype with this Squirreltail Fescue 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 Squirreltail Fescue 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 Squirreltail Fescue from Western Australia 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 Squirreltail Fescue from Western Australia.
 
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CONTRIBUTING WEED SCIENTISTS

MICHAEL ASHWORTH
PhD Student
University of Western Australia, School of Botany
Australian Herbicide Resistance Initiative
University of Western Australia
Crawley, 6009, Western Australia
Australia
Email Michael Ashworth
Web   : Web Site Link
STEPHEN POWLES
Professor And Research Director
University Of Western Australia
School Of Plant Biology
2276 Dahlk Circle
Crawley, 6009, Western Australia
Australia
Email Stephen Powles
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Western Australia have been instrumental in providing you this information. Particular thanks is given to Michael Ashworth, and Stephen Powles for providing detailed information.
Herbicide Resistant Squirreltail Fescue Globally
(Vulpia bromoides)
Herbicide Resistant Squirreltail Fescue Globally
(Vulpia bromoides)
Drag a column header and drop it here to group by that column
Herbicide Resistant Squirreltail Fescue Globally
(Vulpia bromoides)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Australia (Victoria) AustraliaVictoria1990 Alfalfa diquat, and paraquat 1 PSI Electron Diverter (D/22)
173Vulpia bromoidesSquirreltail Fescue17
2 Australia (Victoria) AustraliaVictoria2009 Pastures simazine 1 Photosystem II inhibitors (C1/5)
173Vulpia bromoidesSquirreltail Fescue7841
3 Australia (Western Australia) AustraliaWestern Australia2014 Pastures simazine 1 Photosystem II inhibitors (C1/5)
173Vulpia bromoidesSquirreltail Fescue11030
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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Sunday, July 23, 2017 .  Available  www.weedscience.org
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