Common ragwort (Senecio jacobaea) is usually a biennial plant, producing a rosette in the spring of the 1st year and flowers between May and October of the 2nd year - although disturbance to the plant can cause it to live for longer periods. It has characteristic dark green leaves, tough stems and yellow daisy-like flowers. Rosettes consist of a circular cluster of leaves with a ragged appearance (hence the name), usually deep green on top and cottony underneath. The rootstalk, leaf stalks and lower parts of the stem may have a purple/red colour.
Most plants die off following flowering, making way for immediate colonisation by the seedlings. The seeds have a downy appendage making them readily dispersible by the prevailing wind. They can also be dispersed via water or inadvertently transported by humans or livestock. Each plant can produce up to 150,000 seeds with a 70% germination rate – with seeds remaining dormant in the soil for up to 20 years. Mature ragwort can grow up to 1-2 metres in height and it proliferates on roadside verges, railway tracks, wasteland and pasture. It prefers light soils of low fertility, particularly in over- or under-grazed pasture.
Common ragwort can often be identified by the presence of Cinnabar moth caterpillars (Tyria jacobaeae), as these caterpillars feed almost exclusively on ragwort. The caterpillars are distinctive, black with gold stripes, and grow up to 30mm long.
What are the Dangers of Common Ragwort?
Ragwort is one of the most frequent causes of plant poisoning of livestock in Britain, with equines and bovines being more susceptible than others – particularly the young. It can also be poisonous to people and has been suspected of causing liver damage in those who seek to pull the plant without the benefit of protective clothing.
Ragwort poisoning can occur at any time of year. Ragwort acts as a cumulative poison, eventually destroying the liver, and a small intake of ragwort over a long period can be just as damaging as a large intake on a single occasion. Clinical symptoms of poisoning by ragwort are loss of condition (weight loss, dull coat, depression), poor appetite and constipation, photosensitisation (sunburn) and sometimes jaundice. The development of nervous behaviour, restlessness and aimless uncoordinated movement are some of the common terminal symptoms. Animals may appear blind, press their heads against solid objects and develop an abnormal gait and stance. Animals can die after as little as a week, though some can survive several months. Little can be done for an animal once the clinical symptoms appear.
Livestock tend to avoid eating ragwort on good pastures but it is advisable, as a precaution, to ensure horses do not have access to plants. The poisons in ragwort are not destroyed by drying out and the plant becomes much more palatable when cut or wilted, as it loses its bitter taste. Therefore all cut material must be removed from site. Common sources of ragwort poisoning are dried grass, hay and silage where it can lie undetected and be consumed readily.
Common ragwort is the only ragwort species specified in The Weeds Act of 1959 (other species of Senecio are not so widespread). Under The Weeds Act, the Secretary of State may serve an enforcement notice on the occupier of land on which injurious weeds are growing, requiring the occupier to take action to prevent the spread of these weeds. Responsibility for weed control rests primarily with the landowner. Further information on a landowners responsibilities in regard to The Weeds Act can be found in the Department for Environment Food and Rural Affairs (DEFRA) leaflet "The Weeds Act 1959 – Preventing The Spread of Harmful Weeds", which is available from DEFRA publications and also on the DEFRA website.
The Ragwort Control Act came into force on 20 February 2004 as an amendment to The Weeds Act and enabled the Secretary of State to draw up a Code of Practice to prevent the spread of ragwort. By promoting good practice and good neighbourliness the Code aims to reduce significantly the risk posed by ragwort poisoning. It is particularly relevant for large-scale organisations, including local authorities and public bodies, and provides comprehensive guidance on how to develop a strategic and more cost-effective approach to weed control. It gives advice on the identification of Common ragwort, risk assessment and priorities for ragwort control, control methods, their suitability and efficiency, environmental considerations and health and safety issues. Under the Ragwort Control Act, the Code is admissible in enforcement proceedings under The Weeds Act, which will make it easier to prosecute those who disregard the need to control ragwort. Similarly, those who have followed the guidance laid down in the Code would be able to use this in their defence in any Court proceedings.
It should be noted that the Code does not seek to eradicate ragwort completely. It is important to remember that, where there is no threat to animal welfare, Common ragwort is a native species and makes an important contribution to the biodiversity of the countryside.
How to get rid of Common Ragwort
Active control of Common ragwort is the only way to avoid the risk of ragwort poisoning. Control needs to be ongoing and, preferably, combined with good pasture management. Over-grazing and under-grazing creates open patches of land where ragwort can readily establish itself. Ragwort will not establish where there is a dense vigorous grass sward. Such a pasture can be best achieved through controlled grazing and/or regular fertiliser applications. This encourages root development of grasses and makes a valuable contribution to preventing re-infestation.
Cutting and stem removal at the early flowering stage reduces seed production but does not destroy the plant. It is acceptable in an emergency situation but is generally not recommended long-term as it encourages more vigorous re-growth. Pulling or digging is a popular method of control but experts believe its effectiveness as anything other than an emergency short-term measure is severely limited. If carried out, this operation needs to be performed before flowering has completed and it is important to remove as much of the root as possible since ragwort can regenerate from its root fragments. All wilted and dead Ragwort from the pasture should be removed and burned. Always wear gloves when carrying out this operation.
No single herbicide application will completely eliminate a ragwort infestation due to successive germinations of the weed. Treatment with selective herbicides can be made in the spring but, as ragwort is a biennial, control measures will have to be conducted for at least 2 years (and probably longer). To be fully effective, treatments should be applied early in the first year of the plant’s growing cycle (rosette). Once it has begun to produce flowers eradication will become a time-consuming and long-term process.