15 September 2014
The Ragwort plant (Senecio jacobaea) is a pretty yellow flowering plant that is absolutely deadly to livestock but especially to horses because it contains pyrrolizidine alkaloids. The one saving grace is that it doesn’t taste good but once cut and dried is edible and still retains its toxicity. These toxic compounds principally cause damage to the liver that can lead to death. It is most important, therefore, that humans take precautions when handling the plant i.e. wear gloves and face mask.
When a horse eats Ragwort, the pyrrolizidine alkaloids it contains is 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. Therefore, consuming small amounts over a long period of time is just as dangerous as consuming a large amount in a single session.
Sadly, for the horse displaying clinical signs, bizarre or depressed behaviour , jaundice, weight loss, diarrhoea and photosensitisation (inflammation of unpigmented areas of skin when exposed to sunlight) it is too late – liver failure has occurred.
That is why it is imperative to control Ragwort and it comes under two Government Acts – The Weeds Act (1959) and The Control of Ragwort Act (2003). The responsibility for the control rests with the occupier of the land on which it is growing. 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 us involved with horses and copies can either be ordered directly from DEFRA or from the British Horse Society.
The BHS in its Ragwort Awareness Campaign gives a Code of Practice as follows:
“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:
These categories must be seen only as guidelines, however, as there are many factors that determine the risk posed by growing Ragwort e.g. 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.”
Every year, we dig out Ragwort from our fields making sure we extract all of the root and although the fields are clean when we finish – back they come again the next year as the Ragwort is a biennial plant. So it is a never ending job – although reducing in the amount of plants coming through each year. Burning is the preferred option for disposal of the pulled plants.
The other alternative is to spray with herbicide, although this works best when the plants are young and at the rosette stage. Spring is the ideal time especially if the land is to be used for grazing – however, if it is to be used for forage production, spraying should take place earlier, in the autumn prior to next season’s haymaking. A list of approved chemicals can be found at www.pesticides.gov.uk. Spraying should only be carried out by a competent person and a risk assessment undertaken if there is a likelihood of herbicide contaminating a water source. Pasture should be rested following spraying according to the guidelines issued by the herbicide manufacturer.
All grazing animals can be contaminated by the plant and although sometimes sheep are used to “clean up” a field – this doesn’t mean that they are immune to the Ragwort – it’s just that their life span is short and the toxicity doesn’t get as long a period to damage the liver.
If you have land, please think about the problems that the Ragwort causes and implement some sort of control.
For further information and advisory literature on Ragwort, contact The British Horse Society Welfare Department on 01926 707791 or via email at firstname.lastname@example.org. Defra may be contacted on 08459 335577