International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Galinsoga ciliata)

Photosystem II inhibitors (C1/5)

Hairy Galinsoga (Galinsoga ciliata) is a dicot weed in the Asteraceae family.  In Germany this weed first evolved resistance to Group C1/5 herbicides in 1980 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.

If we do not have a picture for this weed, or you can provide a better picture (scan, digital camera etc) please please e-mail it to us.

QUIK STATS (last updated Sep 15, 2000 )

Common NameHairy Galinsoga
SpeciesGalinsoga ciliata
GroupPhotosystem II inhibitors (C1/5)
Situation(s)Corn (maize)
Contributors - (Alphabetically) 
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Kees-H (1988). The development of triazine-resistant annual weeds in Bavaria and experience with their control. Die Entwicklung triazinresistenter Samenunkrauter in Bayern und Erfahrungen mit deren Bekampfung. Gesunde-Pflanzen. 1988, 40: 10, 407-412, 414.

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Confirmation Tests

Greenhouse trials comparing a known susceptible Hairy Galinsoga biotype with this Hairy Galinsoga biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.

Genetic studies on Group C1/5 resistant Hairy Galinsoga 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 Hairy Galinsoga from Germany.
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The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Germany have been instrumental in providing you this information. 
Herbicide Resistant Hairy Galinsoga Globally
(Galinsoga ciliata)
Herbicide Resistant Hairy Galinsoga Globally
(Galinsoga ciliata)
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Herbicide Resistant Hairy Galinsoga Globally
(Galinsoga ciliata)
#CountryFirstYearSituationActive IngredientsSite of Action
1 GermanyGermany 1980 Corn (maize) atrazine 18 Photosystem II inhibitors (C1/5)
92Galinsoga ciliataHairy Galinsoga441
2 SwitzerlandSwitzerland 1991 Corn (maize) atrazine 41 Photosystem II inhibitors (C1/5)
92Galinsoga ciliataHairy Galinsoga204
Literature about Similar Cases

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