• Key characteristics
  • Biology
  • Impacts
  • Control
  • Further information

  • Perennial, reaching up to 1 m tall
  • Yellow glossy flowers 15 – 25 mm across with 5 petals appear mainly between November and April
  • A short rhizome (horizontal underground stem up to about 100 mm long) with fibrous remains of old leaves, axillary buds and fleshy roots
  • Leaves large (as big as your outstretched hand), hairy, divided into 3-7 lobes, on long hairy stems
  • Avoided by dairy cattle due to bitter taste
  • Common in swamp and wasteland areas, river flats and dairy pastures in high-rainfall areas.

Origin

  • Probably brought from Europe (its native range) or Asia by early settlers. It has invaded many parts of the Southern and Northern hemispheres, including North America, South Africa, Tasmania in Australia and New Zealand.

Life cycle

  • Giant buttercup is a short-lived rhizomatous perennial, with individual plants flowering and producing seeds and daughter rhizomes for several years before dying
  • Seeds germinate from late autumn (May) to late spring (November)
  • Leaf growth peaks in late spring
  • Leafy daughter shoots are produced throughout summer and autumn as branches on the parent plant’s rhizomes, resulting in a slow outward creep of the plant and the creation of patches
  • Flowering stems die back after the seeds are shed and are replaced by the daughter shoots which overwinter as leafy rosettes
  • Seeds fall close to the parent plant and remain dormant for several years in the soil
  • The seeds each have a small hook enabling them to attach to, and be readily spread long distances by grazing cattle and other animals
  • Other long-distance seed dispersal vectors include hay, farming equipment, roadside mowers, footwear, clothes and flood waters.

Benefits

  • Provides nectar for bees
  • Scented flowers attract and provide food for moths and many other small insects
  • In the past the plant has been used medicinally as a last resort cure for syphilis. However, safer medicines are now readily available.

Impact on pasture

  • At peak cover (November) giant buttercup can occupy 50% of a pasture (Bourdôt et al. 2003)
  • Dairy and other grazing cattle avoid the plant and its surrounding pasture thus reducing the stock-carrying capacity of the grazing land
  • On a typical Golden Bay dairy farm giant buttercup reduces overall farm profit by $1,040/ha or 36% (Bourdôt et al. 2012)
  • Resistance to herbicides that once provided adequate control has evolved in giant buttercup on many dairy farms, leaving these farmers without an effective solution (Lamoureaux & Bourdôt 2007)
  • All of New Zealand is climatically suitable for giant buttercup so dairy farmers should learn how to distinguish it from the other less troublesome buttercups (Bourdôt et al. 2013)
  • Giant buttercup can outcompete and reduce clover and grass through competition
  • Rapid increase in the amount of giant buttercup in a paddock can occur due to seedling establishment in “pugged” areas in a pasture (Lusk et al. 2009)
  • Seeds may also be spread by sticking in mud on the hooves and coats of animals.

Impact on stock

  • Protoanemonin, a toxin created during the ingestion of giant buttercup can cause blistering of the tongue and lips of cattle, ventricular fibrillation, intestinal disorders and respiratory failure
  • It has been estimated that giant buttercup is responsible for an industry loss nationally of $150 million annually due to lost milk solid revenue.

Grazing management

  • Giant buttercup may be eaten by sheep which could partly explain why it is never a problem in sheep-grazed pastures. However, cattle avoid eating the plant which makes it much more of a problem on dairy farms
  • Dairy and beef cattle encourage the dominance of giant buttercup by eating its competitors (e.g. grasses, clover)
  • Overgrazing and pugging encourage giant buttercup and should be avoided.

Grubbing / mowing of pastures

  • Mowing a pasture containing giant buttercup before it flowers (in November) can prevent seeds forming
  • If the plants are mown after flowering, seeds may be spread by the mower
  • Pre- or post-graze mowing may be effective over the longer term, resulting in more edible dry matter in the pasture
  • Growth enhancing additives such as gibberellic acid and liquid nitrogen may be useful
  • Hay made from paddock containing giant buttercup will contain the seeds of the weed and should not be fed out in buttercup-free paddocks
  • Plants can be dug out, but care is required to ensure that rhizomes are completely removed as these can easily re-sprout
  • Disposal of removed plants should be carried out carefully as this prevents the ripening and dispersal of seeds.

Chemical control

  • The ‘phenoxy’ herbicides MCPA and MCPB were once widely effective against giant buttercup but evolved resistance in many pastures has reduced their efficacy
  • Three newer and more effective herbicides are thifensulfuron-methyl, flumetsulam and aminopyralid
  • Aminopyralid, MCPA and thifensulfuron-methyl can cause severe damage to clovers
  • Flumetsulam and MCPB do not damage clovers
  • There are signs that giant buttercup can also develop resistance to flumetsulam
  • Rotation of herbicide mode-of-action groups will help delay the development of  herbicide resistance
  • Mode-of-action mixtures (e.g. MCPA + flumetsulam) may also help delay the development of herbicide resistance
  • Herbicides applied in late winter/spring will be most effective
  • Check withholding periods before the use of any of these chemicals on pasture – there can be a withholding period of several weeks with some herbicides.

 

Herbicides with activity against giant buttercup in pasture
Herbicide active ingredient1,2 Application time Application method Clover damage? Mode-of-action group
Aminopyralid Early spring Hydraulic nozzles Yes O3
Bentazone Early spring Hydraulic nozzles No C3
MCPA Early spring Hydraulic nozzles Yes O1
MCPB Early spring Hydraulic nozzles No O1
Thifensulfuron-methyl Early spring Hydraulic nozzles Yes B
Flumetsulam Early spring Hydraulic nozzles No B

1The registered names of the herbicide products containing these active ingredients are too numerous to list here. Consult your farm advisor, industry rep or the New Zealand Agrichemical Manual for more information. Always follow the application guidelines given on the product labels.

2The efficacies of these herbicides, along with pre-graze mowing and pasture growth promoting products, are currently being compared in a series of field experiments on dairy farms in Golden Bay. The results of these experiments will be added to the information on this webpage as they become available.

Biocontrol

  • Two naturally occurring plant pathogenic fungi found on giant buttercup are known to damage the plant:
    • A species of Gnomonia, will infect the plant but not cause death
    • Sclerotinia sclerotiorum causes a soft-rot disease and death of plants. While lethal to the giant buttercup, this fungus does not damage pasture grasses and clovers
  • The use of Sclerotinia sclerotiorum as a mycoherbicide and the potential of insects as biocontrol agents are topic of current research.
  • Classical biological control options are being investigated whereby microbial and/or insect biocontrol agents from the weed’s native range in Europe would be released in New Zealand.

Bourdôt G, King W, Rennie G 2012. Giant buttercup – modelling the financial benefits of control on a Golden Bay dairy farm. Proceedings of the New Zealand Grasslands Association. Pp. 177-181.

Bourdôt GW, Saville DJ, Crone D 2003. Dairy production revenue losses in New Zealand due to giant buttercup (Ranunculus acris). New Zealand Journal of Agricultural Research 46: 295-303.

Bourdôt GW, Lamoureaux SL, Watt MS, Kriticos DJ 2013. The potential global distribution of tall buttercup (Ranunculus acris subsp. acris); Opposing effects of irrigation and climate change. Weed Science 61: 230-238.

Lamoureaux S, Bourdôt GW 2007. A review of the ecology and management of Ranunculus acris L. in pasture. Weed Research 47: 461-471.

Lusk CS, Lamoureaux SL, Bourdôt GW 2009. Giant buttercup (Ranunculus acris L.) seedling emergence and survival in Golden Bay dairy pastures. New Zealand Plant Protection 62: 222-227.

Popay I, Champion P, James T 2010. An illustrated guide to common weeds of New Zealand. New Zealand Plant Protection Society, Christchurch, New Zealand. 416 p.

Young S 2013. New Zealand Novachem agrichemical manual. Agrimedia Ltd, Christchurch, New Zealand. 767 p.