There has been a great deal of publicity about Ragwort in recent years and the majority of horse owners should already be aware of the danger that this plant poses to their animals. Common Ragwort (Senecio jacobaea) contains pyrrolizidine alkaloids. These toxic compounds principally cause damage to the liver that often leads to death.
Horses are particularly susceptible to the effects of Ragwort but other grazing animals are also at risk and humans should take precautions (such as wearing gloves) when handling the plant. There is a commonly held belief that horses will not voluntarily eat Ragwort. It is true that most animals will avoid it, but it is not enough to rely on this - Ragwort should always be cleared from the pasture.
Where the sward is sparse and over-grazed, horses may consume Ragwort and it has been suggested that some animals may even develop an acquired taste for the plant. When cut or wilted (during hay or haylage making) Ragwort loses its bitter taste, but none of its toxicity. It becomes far more palatable and harder for the horse owner to spot, thus posing more of a danger.
The effects of Ragwort poisoning are cumulative - consuming small amounts over a long period of time is just as dangerous as consuming a large amount in a single session. When a horse eats Ragwort, the pyrrolizidine alkaloids it contains are absorbed into the body from the intestines. The alkaloids then pass to the liver, where they are metabolised to produce toxins that damage liver cells. When these cells die they are replaced by fibrous tissue and a point is eventually reached where there are not enough liver cells left to maintain liver function. By this time, liver failure is inevitable.
Signs of Ragwort Poisoning
The clinical signs of Ragwort poisoning are not normally apparent until liver failure has occurred, and at this point there is usually little that can be done for the affected animal. The signs themselves are typical of liver failure and manifest themselves suddenly and without warning.
A key sign is that the horse will display bizarre or depressed behaviour. This is thought to be because the liver is no longer able to cleanse the blood of chemicals or toxins that may affect the brain. Photosensitisation may also be seen and is the inflammation of unpigmented areas of skin when they are exposed to sunlight. Again, this is thought to be due to the liver's inability to remove toxins. Other signs include jaundice, weight loss and diarrhoea.
Ragwort and the Law
The control of Ragwort comes under two government acts, The Weeds Act (1959) and The Control of Ragwort Act (2003). Similar legislation exists under the devolved administrations. Under the latter named Act, Defra produced a Code of Practice, giving guidance on how to prevent the spread of Ragwort. This should be essential reading for all of those involved with horses and copies can either be ordered directly from Defra or from The British Horse Society.
Responsibility for controlling Ragwort rests with the occupier of the land on which it is growing. The Code of Practice, however, states that it is expected that all landowners, occupiers and managers will co-operate and take collective responsibility for ensuring that effective control of the spread of Ragwort is achieved.
The Code of Practice sets out three categories as guidelines for assessing the risk posed by Ragwort. Where Ragwort is present on land, the occupier should use these categories to determine the extent of action required:
Ragwort is present and flowering/seeding within 50m of land used for grazing by horses and other animals or land used for feed/forage production
Ragwort is present within 50m to 100m of land used for grazing by horses and other animals or land used for feed/forage production
Ragwort, or the land on which it is present, is more than 100m from land used for grazing by horses and other animals or land used for feed/forage production
These categories must be seen only as guidelines, however, as there are many factors that determine the risk posed by growing Ragwort. Prevailing winds, topography, shelterbelts and soil type must all be considered when assessing risk.
The key point to be borne in mind is the likelihood of Ragwort spreading to land used for grazing, and/or the production of feed or forage. The Code of Practice states that, where a high risk is identified, immediate action to control the spread of Ragwort must be taken, and that where the risk is classified as either high or medium, an appropriate control programme should be implemented to ensure that the level of risk does not escalate.
No immediate action is required where the risk is low but, given the ability of the wind to disperse Ragwort seeds, it can be considered good practice to implement a control programme even on low risk sites.
When the presence of Ragwort poses a high risk to horses, other livestock or the production of conserved forages, Defra will take enforcement action under The Weeds Act (1959). Before Defra take action, it is expected that an informal approach will be made to the landowner or occupier by the complainant. Should this fail to elicit remedial action, the relevant Defra Rural Development Service Office should be notified.
Strategies for Controlling Ragwort
It is more efficient, straightforward and cost effective to implement a Ragwort control and prevention programme than to take emergency action where an infestation of the plant has been established. Good general pasture management plays an important role in controlling Ragwort as it can prevent the formation of bare patches in the sward that enable Ragwort to establish itself.
Pasture should not be over-grazed and thus stocking densities should be closely monitored. Poaching of the land is to be avoided, which may necessitate resting pasture particularly in wet conditions. It is also imperative to remove droppings and any stale forage such as hay.
Where Ragwort is present, its removal should take place before it has had the opportunity to seed. Each plant can produce many thousands of seeds, so to minimise the problems caused by Ragwort in the following season, early removal is advisable. However, Ragwort remains toxic after seeding, so late removal is better than taking no action at all.
Spraying Ragwort with herbicide can be an effective control measure, although it works best when the plants are young and at the rosette stage. Older, stemmed plants are more resistant and may, therefore, need repeat sprays. Where land is to be used as grazing pasture, spring is the ideal time for spraying. However, if land is to be used for forage production, spraying should take place earlier - in the autumn prior to next season's haymaking.
The choice of herbicide should be considered carefully. A list of approved chemicals can be found at www.pesticides.gov.uk
A risk assessment should be carried out before any spraying takes place and advice should be sought from Defra if there is any likelihood of the herbicide contaminating a water source. Spraying should only be carried out by a competent person who is suitably trained and qualified, with Defra able to provide more detail on the legislation surrounding spraying.
All affected paddocks should be sprayed at once, where feasible, to avoid Ragwort contaminating bare areas left by dead weeds. As the Ragwort dies, it must be removed and disposed of appropriately before pasture can be grazed as the plant becomes more palatable, but no less toxic, as it dries out after death.
Pasture should be rested following spraying according to the guidelines issued by the herbicide manufacturer. Most herbicides are toxic to animals, and thus a safety window is vital before the land is grazed again.
A second option is to pull the Ragwort out by hand. This is likely only to be appropriate where the levels of Ragwort are relatively low, as it is highly labour intensive. There are, however, a number of tools, such as the Rag-Fork, available to make the task easier. Pulling by hand is likely to leave root fragments in the ground, so new growth must be monitored and repeat pulling is likely to be needed annually. All Ragwort that is pulled up must be removed from the pasture and disposed of appropriately.
Burning is the favoured option as it prevents animals from accessing the dried, and therefore more palatable, plants. Any individuals handling Ragwort should wear protective gloves and a facemask to ensure their own safety. For best results, pulling should be completed in spring and summer before the Ragwort has had chance to seed. The task is easiest when the soil is damp.
There are some machines available that will pull Ragwort mechanically but these rely on the Ragwort plants being taller than the rest of the sward. Their use is also limited to certain soil types and topographies. Mowing or cutting Ragwort is not generally advised as it can actually encourage growth. However, it may be necessary as an emergency measure to prevent a Ragwort infestation from seeding. If this option is to be taken, cut Ragwort must be removed and safely disposed of before animals are allowed to return to the pasture. It is not a safe option if the land is to be used for forage production.
Disposing of Ragwort
Ragwort loses much of its bitterness once dead and dried out, but it retains its toxicity. For these reasons, it is essential that removed Ragwort be disposed of appropriately. Any movement of Ragwort to facilitate its disposal must be carefully managed to avoid the dispersal of seeds, therefore sealed bags or containers should be used.
All personnel involved in Ragwort disposal should wear protective gloves and a facemask. Burning Ragwort is perhaps the most suitable option, although this must be carefully managed to avoid environmental contamination and public nuisance.
Some local authorities have bylaws preventing the burning of garden waste, so incineration is not a viable option in these areas. It is suggested that, if Ragwort is to be burned, a recognised incineration device is used, as this will offer greater control and safety than a bonfire-type approach. In order to burn effectively, the Ragwort will need to be wilted.
Care must be taken during the wilting process to avoid the dispersal of seeds. Sealed paper sacks, which can then be burned themselves, offer a safe means of storing Ragwort and allowing some wilting. Alternatively, wilting can take place under cover or seed heads removed from plants and stored in sealed bags prior to wilting. It is imperative that no grazing animals have access to Ragwort during the wilting process.
For small amounts of Ragwort, collection of the plant as domestic refuse may be acceptable. However, the local authority should be contacted before this option is utilised. The Ragwort should be contained in a sealed double layer plastic sack and should not be mixed with other "green waste" unless the local authority has expressly approved this.
Where there is any doubt over how Ragwort should be disposed of, the local authority should be contacted for assistance. Non-domestic disposal is differently regulated and therefore the Environment Agency should be contacted in such situations.
For further information and advisory literature on Ragwort, contact The British Horse Society Welfare Department on 02476 840571 or via email at email@example.com. Defra may be contacted on 08459 335577.Back to Articles