The small yellow flowers are a common feature in many equine pastures, but are buttercups poisonous to horses? Emmeline Hannelly, the British Horse Society’s (BHS) welfare education manager, explains the dangers and how owners can control them.

Toxicity

There are a variety of buttercups including Meadow, Creeping and Bulbous, which thrive on poor quality land, old meadows and grassland. Each variety is poisonous to varying degrees in its fresh state. However, due to its bitter taste, most horses will avoid eating buttercups and instead attempt to graze the grass around the plant.

Be aware that horses or ponies on overgrazed or restricted grazing may revert to consuming buttercups in place of no other forage being provided. If eaten in large quantities, toxicity can result in excessive salivation, diarrhoea or colic.

The toxin contained by buttercups can be an irritant to sensitive skin including the lips, muzzles and lower limbs. The toxin reaches its peak during the flowering period with the irritating effects further exacerbated in wet weather making showers a riskier period.

In its dried form, buttercups lose their bitterness and toxicity so pose no risk once wilted and included in hay.

Control

There are two main areas to focus on for controlling buttercups; the type of buttercup; and the timing of applying the herbicide. The timing and number of applications required will be influenced by the species involved. Harrowing can be effective at reducing creeping buttercups and small patches can be successfully dug out.

The Bulbous buttercup has a more complex root structure which contains a number of bulbils (like little balls) stacked one on top of another and this makes control more difficult as the applied herbicide may not move completely into each of the bulbils. Any that do not receive sufficient herbicide have the potential to re-grow.

The timing of the herbicide application is imperative. Herbicides must be applied as soon as active growth commences in the spring, but before the buttercups flower. The weeds must be dry when sprayed, and because the chemical can take some time to get safely inside the plant, ensure that no rain is forecast for 12 hours after application. It is also essential to avoid herbicide application during periods of frost. Applying the herbicide once flowering has commenced means that any herbicide application is likely to be unsuccessful.

Should the pre-flowering timing be missed, or if any buttercups survive the first herbicide application, September is another opportunity to target those plants. For all applications horses must be removed from the pasture before applying the herbicide and remain off the pasture for at least two weeks after the treatment. There are a number of herbicides currently available on the market for the use on buttercups with varying active ingredients. Some herbicides do require a licence for purchase and application so always seek expert advice from a qualified contractor and always refer to the manufacturer’s instructions.

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Management

Improving grass management and preventing overgrazing of pastures will be beneficial to increasing the grass sward and decrease the opportunity for buttercups to grow. Further information on pasture management is available from the BHS website.

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