International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Soliva sessilis)

Auxin Mimics HRAC Group 4 (Legacy O)

New Zealand
Lawn Burweed (Soliva sessilis) is a dicot weed in the Asteraceae family.  In New Zealand this weed first evolved resistance to Group 4 (Legacy O) herbicides in 1999 and infests Golf courses, and Turf.   Group 4 (Legacy O) herbicides are known as Auxin Mimics (Auxin Mimics ).  Research has shown that these particular biotypes are resistant to clopyralid, picloram, and triclopyr and they may be cross-resistant to other Group 4 (Legacy O) 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 Dec 10, 2013 )

Common NameLawn Burweed
SpeciesSoliva sessilis
GroupAuxin Mimics HRAC Group 4 (Legacy O)
Herbicidesclopyralid, picloram, and triclopyr
LocationNew Zealand
Situation(s)Golf courses, and Turf
Contributors - (Alphabetically)Kerry Harrington 
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Kerry Harrington

Lawn Burweed is known as “Onehunga weed” in New Zealand.

Harrington, KC., Ward, AJ., & Wells, DM. (2001). Herbicide resistance in black nightshade and Onehunga weedNEW ZEALAND PLANT PROTECTION, VOL 54. Vol. 54 (pp. 152 - 156). : 54th Annual Conference of the New-Zealand-Plant-Protection-Society Available at:


For pictures and information about Soliva sessilis, including pictures of resistant vs susceptible plants, visit the following site:

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Confirmation Tests

Greenhouse trials comparing a known susceptible Lawn Burweed biotype with this Lawn Burweed 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 HRAC Group 4 resistant Lawn Burweed 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 4 (Legacy O) resistant Lawn Burweed from New Zealand please update the database.
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Associate Professor in Weed Science
Massey University
School of Agriculture
Private Bag 11-222
Palmerston North, 4442, Manawatu
New Zealand
Email Kerry Harrington
Web   : Web Site Link


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in New Zealand have been instrumental in providing you this information. Particular thanks is given to Kerry Harrington for providing detailed information.
Herbicide Resistant Lawn Burweed Globally
(Soliva sessilis)
Herbicide Resistant Lawn Burweed Globally
(Soliva sessilis)
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Herbicide Resistant Lawn Burweed Globally
(Soliva sessilis)
#CountryFirstYearSituationActive IngredientsSite of Action
1 New ZealandNew Zealand 1999 Golf courses, and Turf clopyralid, picloram, and triclopyr 30 Auxin Mimics ( HRAC Group 4 (Legacy O)
199Soliva sessilisLawn Burweed5107
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