International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Lactuca serriola)

EPSP synthase inhibitors (G/9)

Australia, Victoria
Prickly Lettuce (Lactuca serriola) is a dicot weed in the Asteraceae family.  In Victoria this weed first evolved resistance to Group G/9 herbicides in 2015 and infests Fallow.   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.

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QUIK STATS (last updated Feb 08, 2016 )

Common NamePrickly Lettuce
SpeciesLactuca serriola
GroupEPSP synthase inhibitors (G/9)
LocationAustralia, Victoria
Contributors - (Alphabetically)Christopher Preston 
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Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Prickly Lettuce biotype with this Prickly 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 Prickly 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 Prickly Lettuce from Victoria please update the database.
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University Of Adelaide - Waite Campus
Crc For Australian Weed Management And School Of Agriculture
Box 2146
Adelaide, 5064, South Australia
Email Christopher Preston


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Victoria have been instrumental in providing you this information. Particular thanks is given to Christopher Preston for providing detailed information.
Herbicide Resistant Prickly Lettuce Globally
(Lactuca serriola)
Herbicide Resistant Prickly Lettuce Globally
(Lactuca serriola)
Drag a column header and drop it here to group by that column
Herbicide Resistant Prickly Lettuce Globally
(Lactuca serriola)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Australia (South Australia) AustraliaSouth Australia1994 Canola, Roadsides, Spring Barley, and Wheat chlorsulfuron, flumetsulam, metosulam, metsulfuron-methyl, and triasulfuron 1 ALS inhibitors (B/2)
102Lactuca serriolaPrickly Lettuce26
2 Australia (Victoria) AustraliaVictoria2009 Spring Barley, and Wheat chlorsulfuron, and metsulfuron-methyl 1 ALS inhibitors (B/2)
102Lactuca serriolaPrickly Lettuce5516
3 Australia (Victoria) AustraliaVictoria2015 Fallow glyphosate 1 EPSP synthase inhibitors (G/9)
102Lactuca serriolaPrickly Lettuce11022
4 United States (Idaho) United StatesIdaho1987 Canola, Cereals, Chickpea, Lentils, Peas, and Wheat chlorsulfuron, imazethapyr, metsulfuron-methyl, thifensulfuron-methyl, triasulfuron, and tribenuron-methyl 45 ALS inhibitors (B/2)
102Lactuca serriolaPrickly Lettuce230
5 United States (Washington) United StatesWashington1993 Cereals, and Wheat chlorsulfuron 45 ALS inhibitors (B/2)
102Lactuca serriolaPrickly Lettuce518
6 United States (Oregon) United StatesOregon1993 Wheat chlorsulfuron, metsulfuron-methyl, and triasulfuron 45 ALS inhibitors (B/2)
102Lactuca serriolaPrickly Lettuce1174
7 United States (Washington) United StatesWashington2007 Cereals 2,4-D, dicamba, and MCPA 45 Synthetic Auxins (O/4)
102Lactuca serriolaPrickly Lettuce5328
Literature about Similar Cases

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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Saturday, September 26, 2020 .  Available
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