International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Ranunculus acris)

Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Auxin Mimics HRAC Group 4 (Legacy O)

New Zealand
Tall Buttercup (Ranunculus acris) is a dicot weed in the Ranunculaceae family.  In New Zealand this weed first evolved multiple resistance (to 2 herbicide sites of action) in 2010 and infests Pastures.  Multiple resistance has evolved to herbicides in the Groups 2 (Legacy B), and Auxin Mimics HRAC Group 4 (Legacy O).  These particular biotypes are known to have resistance to flumetsulam, MCPA, and thifensulfuron-methyl and they may be cross-resistant to other herbicides in the Groups 2 (Legacy B), and Auxin Mimics HRAC Group 4 (Legacy O).

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 17, 2016 )

Common NameTall Buttercup
SpeciesRanunculus acris
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

Auxin Mimics HRAC Group 4 (Legacy O)
Herbicidesflumetsulam, MCPA, and thifensulfuron-methyl
LocationNew Zealand
Contributors - (Alphabetically)Graeme Bourdot, Kerry Harrington, and Carolyn Lusk 
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Kerry Harrington

New Zealand Journal of Agricultural Research, 2015

Resistance of Ranunculus acris to flumetsulam, thifensulfuron-methyl and MCPA in New Zealand dairy pastures.

CS Luska, GA Hurrella, KC Harringtonb, GW Bourdôta and DJ Savillec
aAgResearch Ltd, Christchurch, New Zealand; bInstitute of Agriculture and Environment, Massey University, Palmerston North, New Zealand; cSaville Statistical Consulting Ltd, Lincoln, New Zealand

Research in the 1980s showed that Ranunculus acris had evolved resistance to the phenoxy herbicides MCPA and MCPB in New Zealand. Since then two ALS-inhibitor herbicides, flumetsulam and thifensulfuron-methyl, have been used but recently flumetsulam has been reported as being less effective. The mortality responses of seedling progeny of 15 R. acris populations, differing in historical exposure to phenoxy and ALS-inhibitor herbicides, were compared using a log-series of five doses of MCPA, flumetsulam and thifensulfuron-methyl. The resulting mortalities were higher than expected at lower doses, meaning LD50 values were not reliably estimated. In a second experiment, the responses of one population with no previous exposure to herbicides and one population with high exposure to flumetsulam were compared using a wider range of doses of flumetsulam (0.04 to 25 times). The LD50 values differed 5.3-fold between the resistant and susceptible biotypes. In a third experiment, four populations varying in past exposure to both herbicide groups were treated with either flumetsulam or MCPA. Resulting LD50 values were higher in populations with high previous exposure to both groups. These results confirm that resistance to both phenoxy and ALS herbicides can occur in R. acris populations through repeated use. Since these are the only two available groups for the selective control of this weed in dairy pastures in New Zealand, the options for control are reduced.

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Confirmation Tests

Greenhouse trials comparing a known susceptible Tall Buttercup biotype with this Tall Buttercup 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 2, 4 resistant Tall Buttercup 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 multiple resistant Tall Buttercup from New Zealand please update the database.
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Canterbury Agricultural & Science Centregerald
Street, P.o. Box 60
New Zealand
Email Graeme Bourdot
Massey University
624 Betts Rd
Palmerston North
New Zealand
Email Kerry Harrington
Science technician
AgResearch Ltd
Gerald St & Springs Rd
Christchurch, 8140, Canterbury
New Zealand
Email Carolyn Lusk
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 Graeme Bourdot, Kerry Harrington, and Carolyn Lusk for providing detailed information.
Herbicide Resistant Tall Buttercup Globally
(Ranunculus acris)
Herbicide Resistant Tall Buttercup Globally
(Ranunculus acris)
Drag a column header and drop it here to group by that column
Herbicide Resistant Tall Buttercup Globally
(Ranunculus acris)
#CountryFirstYearSituationActive IngredientsSite of Action
1 New ZealandNew Zealand 1988 Pastures MCPA 30 Auxin Mimics (O/4)
140Ranunculus acrisTall Buttercup159
2 New ZealandNew Zealand 2010 Pastures flumetsulam, and thifensulfuron-methyl 30 Inhibition of Acetolactate Synthase (B/2)
140Ranunculus acrisTall Buttercup5732
3 New ZealandNew Zealand 2010 Pastures flumetsulam, MCPA, and thifensulfuron-methyl 30 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase (B/2)
Auxin Mimics (O/4)
140Ranunculus acrisTall Buttercup14057
Literature about Similar Cases

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