International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Lactuca saligna)

EPSP synthase inhibitors (G/9)

Australia, Western Australia
Willow-leaved lettuce (Lactuca saligna) is a dicot weed in the Asteraceae family.  In Western Australia this weed first evolved resistance to Group G/9 herbicides in 2017 and infests Vegetables.   Group G/9 herbicides are known as EPSP synthase inhibitors (Inhibition of EPSP synthase).  Research has shown that these particular biotypes are resistant to glyphosate and they may be cross-resistant to other Group G/9 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 Nov 27, 2017 )

Common NameWillow-leaved lettuce
SpeciesLactuca saligna
GroupEPSP synthase inhibitors (G/9)
LocationAustralia, Western Australia
Contributors - (Alphabetically)Abul Hashem 
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Confirmation Tests

Greenhouse trials comparing a known susceptible Willow-leaved lettuce biotype with this Willow-leaved lettuce 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 G/9 resistant Willow-leaved lettuce 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

There is no record of differences in fitness or competitiveness of these resistant biotypes when compared to that of normal susceptible biotypes.  If you have any information pertaining to the fitness of Group G/9 resistant Willow-leaved lettuce from Western Australia please update the database.
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Senior Research Officer (weed Science)
Agriculture Western Australia
Department Of Agriculture And Food Wa
Hampton Roads Ag Res And Ext Center
1444 Diamond Springs Rd,
Northam, 6401, Western Australia
Email Abul Hashem


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 Abul Hashem for providing detailed information.
Herbicide Resistant Willow-leaved lettuce Globally
(Lactuca saligna)
Herbicide Resistant Willow-leaved lettuce Globally
(Lactuca saligna)
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Herbicide Resistant Willow-leaved lettuce Globally
(Lactuca saligna)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Australia (Western Australia) AustraliaWestern Australia2017 Vegetables glyphosate 1 EPSP synthase inhibitors (G/9)
336Lactuca salignaWillow-leaved lettuce17111
Literature about Similar Cases

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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Friday, September 25, 2020 .  Available
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