Bright yellow ragwort might be a pretty plant but it is highly poisonous to grazing animals and can have a devastating effect, especially on horses. Common ragwort (Senecio jacobaea) is a biennial plant about 30-90 cm tall, which forms a rosette in its first year, then grows tall and flowers during its second year. However, the plant does act as a perennial – coming back every year – if it is cut or partially dug up. It contains toxins called alkaloids, which cause liver damage and can cause death. The fresh plant is unpalatable but when cut and dried, for example in hay, after herbicide is applied, or the plant has been trampled, it becomes quite palatable. The poison has a cumulative effect and the plant can kill from either a large single intake or small intakes over a period of time.
Common ragwort is widespread throughout the UK and is a particular problem on poorly managed horse pastures. It spreads by prolific seed production from plants on neighbouring ground.
The plant is classified as an injurious weed under the 1959 Weeds Act and landowners must, by law, control the plant. A ragwort code of practice on how to prevent its spread has been produced by Defra, and can be found here.
Controlling ragwort is not just essential for horse health – it is a legal obligation. Good grassland management is key because keeping pasture healthy suppresses ragwort seedlings. Overgrazing and poaching encourage bare patches of ground, allowing ragwort to become established. Grazing pasture containing the rosette stage of ragwort by sheep is sometimes used to help control it, but ragwort is poisonous to sheep, albeit in higher quantities than to horses.
Hand or machine pulling can be effective, but is best done after rain or by digging up to ensure no root fragments are left, because these can grow into a new plant. Foliage must be removed and burnt because pulled plants can still produce viable seed. Cutting is not helpful because although it stops seed production, it stimulates growth and the plant will re-flower later. Cut plants left in the field are dangerous because they remain toxic and are more palatable. When pulling plants, gloves must always be worn because the alkaloid poison can travel through the skin.
Herbicides can be used to control ragwort but an effective chemical is essential and it must be used with care and as directed. Some are only effective whilst the plant is actively growing so the labels must be studied and the correct chemical used for that time of year. Pasture treated with herbicide must not have horses grazed on it until treated plants are completely decomposed and disappeared (at least 4 weeks and possibly longer).
Taking control of ragwort is essential to help stop its spread on grazing land, and keep pastures safe for horses, ponies and other stock to graze.
**Update Wednesday 14th May 2014**
Thank you to the reader who questioned the legal information in this blog, and following is a statement to clarify the situation:
It is every landowner’s obligation to ensure that common ragwort does not spread to grazing land. Under the Weeds Act 1959, landowners who do not control common ragwort can have an enforcement notice served to them, requiring them to take action to prevent it from spreading. Landowners must, by law, control the ragwort if they have a notice served on them to do so and an unreasonable failure to comply with a notice is an offence. Defra’s Code of Practice for control will be used in evidence in enforcement proceedings, making it easier to prosecute those who disregard the need to control ragwort.