Injurious "Weeds" POLICY
The Knepp Estate July 2009
2008 was the “year of the ragwort”. It was so abundant everywhere, not just at Knepp, that it sparked considerable debate. We carried out our own research in an effort to dispel some of the myths that surround the plant and allay the fears of some of our neighbours, and decided to set up a policy to ensure that our Wildland Project stays on the right side of the Weeds Act 1959, whilst allowing this valuable wildflower to behave naturally in areas away from boundaries.
Did you know for example that at least 30 species of insects and other invertebrates are totally dependent on Ragwort as their food Click on Buglife website.
The policy was prepared by Theresa Greenaway following consultation with our Steering Group, a voluntary but informed group of eminent scientists and land managers.
Frequently Asked Questions FAQ
The points raised, as supplied by David Meadows (Chair of the Shipley Parish council), are dealt with below. David Meadows has also drawn attention to a website of Ragwort Facts – Information on Ragwort in the UK from a scientific perspective www.ragwortfacts.com/index.html – the reading of which is recommended. A (translated) Dutch website www.ragwort.jakobskruiskruid.com also provides a more European perspective.
There is concern that R. is spreading to a large area of the Parish. There is no doubt that R. has spread to areas where it has not been seen, including gardens – As stated earlier in this report, over 60% of ragwort seed falls within 4.5m (15ft) of the parent plant. Clearly, ragwort needs to be controlled within the High Risk zone, but an increase in the parish overall cannot realistically be blamed entirely on Knepp.
The perception by local people and visitors is that the countryside on large areas of Knepp is not well managed – KCE has taken considerable trouble to let people know about the wildland project, and the changes this will entail. It is understood that many people do not like to see changes, and the transition from intensive arable to a mixture of parkland, scrub and woodland does to many look like ‘bad’ management. Another point of view is that the wildlife – birds, wild flowers butterflies etc – will benefit greatly from these changes. In fact, there is already evidence that some of the UK’s declining bird species are actually on the increase in Knepp – including in 2008 for the first time, two male woodlarks. So the opinion of those who would prefer ‘farmland’ to ‘wildland’ has to be balanced against those who prefer ‘wildland’ to ‘farmland’.
There is a need for clear scientific information to be available to local people so that they are able to understand why Knepp should be in a position to allow the growth and spread of huge quantities of pernicious weeds and at the same time be in a position to receive supporting funding – The ‘pernicious weeds’ are essentially those that flourish on bare ground. As a stable sward develops, the level of these weed species is predicted to fall. There is, in fact, a considerable amount of scientific information on vegetation succession, although admittedly it tends to be in scientific publications to which the general public may not have ready access. The supportive funding currently received by KCE is for the overall project, and possibly contentious developments such as weed proliferation are kept under review. Supportive organisations such as Natural England are working with Knepp to reduce any aspect perceived as damaging by neighbours. Are intensive farms in receipt of agricultural subsidies entirely weed-free?
In an article in the Daily Mail last year – Graham Harvey August 2007 – (see Daily Mail website and put ‘Ragwort’ in Search) it is stated that pollen taken by bees for local honey contains toxins. It also states that inhaling pollen can lead to liver damage in people. Clearly these problems are greatest where there is a large quantity of R., which there appears to be on the Estate. These claims require a scientific response so that everyone is sure there is no danger to the health of the general public – The Defra Code of Practice and the HMSO ‘Poisonous Plants and Fungi’ state that the risk of poisoning from honey containing ragwort pollen or nectar is ‘highly unlikely’ or ‘negligible’ in Britain. The Code of Practice was drawn up in consultation with the British Beekeepers’ Association. Bees collect nectar and pollen from many other poisonous plants in the UK – honey also undoubtedly contains residues from pesticides and other environmental contaminants, as does much of the rest of the food we eat. The publications cited do constitute ‘scientific response’, but our knowledge in any field of human health is never complete. We can only act on new, scientifically verifiable, information as it becomes available.
At the meeting last week it was stated that pulling ragwort will encourage more to grow. This goes against the experience of people who have pulled R. to clear it from paddocks. I still have my Agricultural Botany book by John Percival which in the note on R. states ‘When it’s stems have been allowed to grow up, hand pulling after rain exterminates it’ He also says that the fruits blow about like groundsel and thistle – Ragwort can and will grow from fragments of root left behind in the soil; this is a botanical fact. This does not mean that it will ALWAYS regrow. Pulling it after rain will allow a more complete plant to be pulled, so fewer bits are left behind. Undoubtedly pulling plants will help, but it is not the answer over large areas, and it will not stop re-colonisation. Yes, of course the seeds blow about, they are wind-dispersed, but most of them fall close to the parent plant. But this also means that not all of the ragwort in Shipley comes from Knepp.
At the meeting I believe that the number of animals dying each year from poisoning was greatly understated. The British Horse Society believes that a figure of 6,500 horses per year is likely. Talking to knacker workers would support that large numbers die – it is unlikely that anyone truly knows the correct figure, although it is considered that the figure of 6,500 is an exaggeration based on the faulty analysis of a small sample survey (See Ragwort Facts weblink). In any case, autopsies are seldom carried out, and a number of other plants can also poison livestock and will, because liver damage is caused, show similar symptoms to ragwort poisoning. The Defra Code gives an extrapolated figure of 500 horse deaths in 2000, and the weblink Ragwort Facts gives 13 in 2005, and addresses this issue further. However, as far as a horse-owner is concerned, one death is far too many. The Defra Code of Practice has been drawn up in conjunction with the British Horse Society, English Nature, ADAS and other organisations, and this Code should be read by all concerned – it is readily available either on the web or as a (free) hard copy.
It is incomprehensible that any organization supporting organic farming would sanction a system where no control of Injurious Weeds was attempted – again, please refer to the Defra Code of Practice, which contains advice and procedures for organic farmers. It is a question of informed balance.
The agricultural value (ability to produce food) of the land in a ‘no control’ situation has to be of concern for the future. The seed bank and in due course especially to drainage systems – The seed bank of non-agricultural plants will undoubtedly increase, this is considered one of the benefits of rewilding. Not all of these will rank as ‘pernicious weeds’. Soil structure, microclimate and nutrient level may well improve; the brown earths that develop under deciduous woodland are known for their fertility, which is one reason why woodlands were cleared in the first place. Low Weald clay, as all those who farm or garden on it know, is inherently of poor fertility, is difficult to work and drains poorly. It is accepted that the roots of plants such as willows may damage field drains, which would then need replacing if land use changed in the future. But Knepp is not being put under tarmac, housing, concrete – or even sand schools. Should future events dictate, the changes underway are by no means irreversible and it is disingenuous to suggest there is cause of concern for the future.
Although grazing animals appear to avoid R., where there are large quantities some may be broken to become dry and palatable; animal welfare is therefore an important issue – yes, undoubtedly, which is why the estate is keen to implement a ragwort control policy. All ragwort eventually dies, but if it is not mixed with other plants in hay or silage, livestock may better be able to avoid it. The estate is continually assessing any risks from ragwort to its own livestock.
Where fields have been seen to contain wall to wall R. in previous years there now seems to be a reduction to a lower but still significant level. This is not however a reassuring situation – the ragwort control policy will continue to work to reduce the risk of ragwort spreading from the High Risk zone.
There would not seem to be any call to eradicate R., (and other listed plants in the Injurious Weeds Act) but that there should be control that is understood as policy, which is seen to be carried out – the estate’s ragwort control policy is and will continue to be carried out. The implementation of it will also reduce other wind-dispersed species such as creeping and spear thistle. This policy is available to all those wishing to read it.
Will the Ragwort and other Injurious Weeds Control Policy prevent harm to Knepp’s own livestock? – The estate does not want its own livestock harmed by ragwort ingestion. It has taken advice from relevant organisations including the Grazing Animals Project. The opinion of participants on the GAP discussion line is that animals are not interested in ragwort that dies naturally but will eat cut stems that have dried, either on the ground or in a hay mixture. Our Steering Group member from the RSPCA has also found that there is a risk of precocious youngsters chewing on fresh ragwort out of curiosity. It is hoped in these circumstances that the unpalatable taste would be aversive to them.
Policy for Injurious Weed Control on Knepp Castle Estate.
By Theresa Greenaway, 21st October 2008
Knepp Wildland Project The Knepp Wildland Project has been underway since 2001. Most of the Estate, previously intensively farmed, has been taken out of arable production in stages since 2001. The reasons behind the decision to abandon intensive farming in favour of re-wilding are given in depth in the Knepp Castle website. The land is now grazed by low numbers of longhorn cattle, Exmoor ponies, fallow deer and Tamworth pigs.
Land that suddenly ceases to be under an arable crop is susceptible to a proliferation of plants that quickly colonise bare soil. Five of these are considered to have such a high nuisance value that they have been specified under the Weeds Act, 1959, and at least three of these have increased in abundance on some of the land within the Knepp wildland project, which has been a cause of concern to neighbours. This resulted in representation being made to the estate by Shipley Parish Council in 2008.
The estate has no wish for its wildland project to have a negative impact on neighbouring land interests. We have therefore drawn up and implemented a weed control policy to reassure those who are unhappy with the level of nuisance weeds that at the same time will not compromise the rationale behind its own aims for the land.
Injurious weeds The five plants specified under the Weeds Act, 1959 are common ragwort Senecio jacobaea, spear thistle Cirsium vulgare, creeping or field thistle Cirsium repens, broad-leaved dock Rumex obtusifolius and curled dock Rumex crispus. All these species are present on Knepp, but it is ragwort and to a lesser extent creeping thistle and dock that are most problematic. The control of weeds of disturbed ground is extremely difficult, even with the use of herbicides in some cases. Airborne seeds of species such as thistles and ragwort need only small patches of bare land on which to germinate successfully.
The Injurious Weeds Act does not make it an offence for any of these five species to be present on land, but is primarily concerned with their control and prevention of spread. This document presents the Knepp Castle Estate Injurious Weed Control policy. It deals in greatest depth with ragwort, as this is known to be highly toxic to livestock.
Ragwort Common ragwort Senecio jacobaea is a native wild plant of the UK. It is also native to the rest of Europe as far a southern Scandinavia and reaches across to Western Asia and North America. It flourishes best on dry, bare or disturbed chalky or limy soils and grasslands although will grow on more acid soil. It fares least well on wetlands, scrub, woodlands including plantations, hedgerows and anywhere generally on acid soils. Ragwort forms a rosette of leaves and a taller flower stem that on average is 30-90cm. This means some plants will be smaller, but some will also be much taller when in ideal conditions. When in flower it is highly conspicuous.
There are some seven other native species of ragwort Senecio spp., and about eleven other introductions that have either escaped from gardens or from sources such as wool shoddy. Three of the native species are more familiarly known as groundsels. Some of the native species are extremely rare and protected or they have very limited distribution. Most of the introductions are also very limited in their distribution.
In Sussex, excluding the groundsels, only two native species of ragwort and one introduction are likely to be encountered to any extent. Common ragwort is by far the most widespread and abundant of these; hoary ragwort Senecio erucifolius is also fairly frequent and dose occur on Knepp and the wider countryside in field margins, verges and other grasslands, although it prefers base-rich soils. Marsh ragwort Senecio aquaticus may grow on marshy ground near rivers and streams. The introduced Oxford ragwort Senecio squalidus grows on waste ground, walls, railway embankments and similar places. Although other species of ragwort – and common groundsel Senecio vulgaris – do contain similar alkaloids to common ragwort, these species are seldom present in sufficient quantity to constitute a threat to livestock.
The number of seeds produced per plant ranges widely, up to 30,000 per plant is cited by some authorities. Many plants will produce far less than this, especially as a variety of insects eat flowers and seeds; and some will produce more. Most, but actually not all, of these seeds have a hairy ‘parachute’ and are thus dispersed by wind. Most ragwort seeds, a figure of 60% has been calculated, fall around the base of the plant, and seedfall decreases with distance such that at about 36m (120ft), 0.005% seedfall occurs. This means that for a plant that does produce 30,000 healthy seeds, 18,000 land at the base of the plant; 11,700 seeds land 4.5m (15ft) away and so on until at a distance of about 36m (120ft), 1.5 seeds land.
Ragwort is one of a large number of European plants that contain distasteful, toxic compounds in order to deter herbivores from eating them. The chemicals contained by ragwort are known as pyrrolizidine alkaloids. These are highly toxic to many mammals including livestock and humans, but are especially poisonous to horses and cattle, either fresh or in hay. However, animals including horses, cattle and their ancestors have lived alongside ragwort in Europe, Asia and Africa for many thousands of years. The weblink Ragwort Facts http://www.ragwortfacts.com/index.htm gives further information on pyrrolizidine alkaloids and the plants that contain them.
It is difficult to be definitive about numbers of seed, the spread of ragwort, and the number of livestock fatalities it causes. Those who call for ragwort to be eradicated will tend to cite the highest seed numbers, rate of spread, number of horses killed per annum and so on, and those who view ragwort as a valuable component of a native flora will tend to cite the lowest. To try to put ragwort into some kind of reasonable context, it is only one of a considerable number of plants that can cause horse and other livestock fatalities if consumed. In southern England, these include some common species such as foxglove, ramsoms, daffodil, cuckoo pint, ivy, white bryony, bracken, black bryony, elder, spindle and of course yew. Others, including bluebell, have also been known to poison horses although not fatally.
Knepp Castle Estate Policy for control of spread of ragwort and other injurious weeds.
As a precaution, all land adjacent to the Knepp Wildland Project boundary will be treated as though it were used for pasture or forage production, including private gardens.The strip of land to a depth of about 50m around the perimeter of the wildland area and around any tenanted or privately owned land embedded within the project area but not part of it (see map) will thus, if ragwort is present, constitute the High Risk Zone identified in the Defra Code of Practice.This c50m strip of land will be topped as necessary to prevent the spread by seeds of ragwort and other injurious weeds to reduce as far as practicably possible the presence of ragwort and other injurious weeds and to prevent their spread onto neighbouring land. Land 50-100m inside the Knepp boundary, if ragwort is present, will be in the Medium risk category, and as such should never change from Medium to High because it is always going to be over 50m from land used as pasture or forage production outside the Wildland Project area.Land over 100m from the boundary will be in the Low risk category and should remain thus even if ragwort does occur at some density.The use of herbicide, as well as not being compatible with the aims of the Wildland project, is not permissible within the terms of the organic status conferred by the Soil Association www.soilassociation.org/certification. Control of ragwort and other injurious weeds will therefore be undertaken by means of topping, which will be done at the end of July / beginning of August each year. Topping earlier than this cannot take place because of ground-nesting birds.Topping will be carried out every year as necessary, as ragwort and other injurious weeds may re-grow or re-colonise from the land outside the buffer zone on KCE as well as from plants outside the Estate. Prior to this Policy, the following measures have been taken to prevent the spread of ragwort: Land where ragwort is present up to 100m inside the Estate boundary has been topped in August. Two heavily ragwort-infested fields near Shipley have been topped. Three fields adjacent to a neighbouring alpaca farm were topped.The total elimination of all ragwort, creeping and common thistle, broad-leaved and curled dock from Knepp Castle Estate is not feasible and, as native wild plants with significant ecological importance, neither is it desirable or a legal requirement under the Injurious Weeds Act.
Indemnity This report is based on information and research considered to be of good scientific origin, and is understood by the author and those consulted to be fair and accurate at the time of writing. It has been compiled on behalf of the Knepp Castle Estate, which is responsible for complying with UK legislation under the Weeds Act 1959. Any new information, provided that it comes from a reputable source, will be considered and any necessary adjustment will be made to the estate’s Control of Ragwort and other Injurious Weeds policy. This policy has been read by other organisations including Natural England and other members of the Knepp Wildland Project Steering group.
The estate will endeavour at all times to follow the Defra Code of Practice on ragwort control, and to control the spread of other species cited in the Injurious Weeds Act 1959. The Knepp Wildland Project is a legitimate use of land by its owner. As with all land usage and change, there are some that will be in favour and some that will not.
Cooper, M.R. & A.W.Johnson, A.W. (1988) Poisonous Plants and Fungi HMSO.
Grime, J.P., Hodgson, J.G. and Hunt, R. (2007) Comparative Plant Ecology Castlepoint Press.
Salisbury, Sir E. (1964) Weeds and Aliens. New Naturalist No. 43, Collins
For more information, look at this extract from Buglife’s fascinating website www.buglife.org.uk
Buglife’s fascinating website
Here is an extract from their piece on Ragwort…
Ragwort Fact File
- At least 30 species of insects and other invertebrates are totally dependent on Ragwort as their food.
- Many other species of insects which eat Ragwort, or require the nectar and pollen from the flowers, can also use alternative plants. However, Ragwort is often significant in supporting viable populations, especially in districts where such alternative plants may be absent or too scarce.
It must be emphasised that Ragwort is a major nectar source for many insects, especially:-
Solitary bees (at least 30 species: 38 cited in one list).* Solitary wasps (at least 18 species; not the sort to harm people). Hoverflies (many species). Conopid flies (parasitic on solitary bees and bumblebees). Butterflies (Small Copper, particularly where other flowers may be scarce) Moths at night (including at least 40 noctuid moths). 3. Ragwort is among the select few plants listed in the Weeds Act (1959). The listing was primarily concerned with control where agricultural production may be affected by its presence, especially its toxicity to grazing stock.
- In 2003, the Ragwort Control Bill has been going through parliament. A Defra code of practice has been produced that will be backed by enforcement of Ragwort control where toxicity is perceived as sufficient risk. In particular, this covers land grazed by horses and hay fields supplying their fodder (these days largely a recreational rather than agricultural issue).
- Both insect faunas and horses (and other farm animals) can co-exist provided control measures are targeted where really needed. In many situations Ragwort is doing no harm.
- If the richness of the fauna is to have a future, the current over-reaction, indeed hysteria in some quarters, needs to be defused. Public and other bodies are seemingly being pressured beyond limits of tangible problems, and the horse fraternity and general public are encouraged to eliminate Ragwort, which in practice often means any plant that looks vaguely similar.
It’s amazing:- The future of so many species is now dependent on an understanding of sustainability: how to make use of the countryside and town whilst maintaining biodiversity.
Ragwort: About the Plant
- Nineteen species of the Ragwort genus, Senecio, occur in the wild in Britain, but most of these are garden escapes or other introductions.
- The main ‘weed’ species is the native Common ragwort (Senecio jacobaea). This thrives where bare ground or thin vegetation allows the development of seedlings into rosettes of leaves splaying out sideways. Later (usually the next year) the rosette develops into a flowering shoot which can tolerate being among other tall vegetation.
Overall Common ragwort supports the most specialist insect species, with the look-alike native Hoary ragwort (Senecio erucifolius) highly significant in being preferred by some insects.
- However, there are other widespread Ragworts with similar sized flowers which can be confused with Common ragwort.
Marsh ragwort (Senecio aquaticus), is not aquatic but occurs locally in wet unimproved fields. The growth form is less tall and the flowering shoots are more splayed-out. Current information suggests that this supports fewer species of special insects but remains important for flowers.
Oxford ragwort (Senecio squalidus), is an introduced plant which has become very widespread as a weed along railway lines and rubbish dumps. Its growth is loosely bushy. At least some insects feed upon it and the flowers are popular with insects.
- The New Atlas of the Flora of Britain and Ireland (2002) shows Ragwort as native and states that ‘the distribution of S. jacobaea is unchanged from the map in the 1962 Atlas’.
- The most recent national Countryside Survey (a national scientific study funded by Government) found no specific evidence of an increase in Ragwort in fertile or infertile grassland (i.e. grazing land) during the period 1990 to 1998. The Countryside Survey did show a significant increase in the frequency of Ragwort in lowland woods and on arable land over that period, but these are both habitats where Ragwort abundance is comparatively low and which are not frequently grazed by horses. The perceived increase in Ragwort abundance seems to be simply a result of increasing awareness resulting from the anti-Ragwort campaign.
- Most of the other widespread native species of Senecio are groundsels. These often have inconspicuous flowers with poorly developed petals, whereas Ragworts have larger bright yellow petals. Grounsels support a relatively poor fauna, and the flowers are little use to insects such as bees. The Sticky groundsel, Senecio viscosus, is used by a few specialist species and the moderately developed petals make the flowers mildly attractive to insects.
- Additionally there are some rare native Senecio. Notably the Fen ragwort (Senecio paludosus) (which grows to 2m in height) and the Welsh groundsel (Senecio cambrensis) (an endemic species of waste ground and waysides).
- It is important to realise that there are other plants with a roughly similar growth-form and yellow flowers. Traveling in a car or on a train can give a false impression that Ragwort is more widespread than may actually be the case. Even on the ground, with limited botanical knowledge it would possible to be confused as to whether plants are Ragworts or not, let alone which Ragwort species. Tansy (Tanacetum vulgare), St. John’s Wort (Hypericum spp.)and Hawkweeds (Hieracium spp.) are among the plants destroyed by mistake, putting at risk their accompanying invertebrate faunas.
- Ragworts have their legitimate place as part of Britain’s biodiversity, together with the large wealth of insects and fungi that they support. A degree of tolerance where these plants are not a tangible threat to horses is all that is sought.
Insect Fauna in Summary
- Ragwort is one of the most important plants in the countryside and on urban waste ground in terms of number of species of insects it supports.
- At least 77 insect species have been recorded eating Ragwort leaves or living in the stems and flowers About 52 of these are known to regularly feed on Ragwort as a significant foodplant.
- More importantly, 30 species of invertebrate are confined to Ragwort as a foodplant. This is a high total for a plant and the great majority are confined to Common ragwort S. jacobaea, the main so called injurious weed or the closely similar Hoary ragwort S. erucifolius.
7 Leaf Beetles
12 Flies Including attractive picture-winged flies.
1 Macro Moth The Cinnabar moth
7 Micro Moths
A further 22 species rely very heavily on Ragwort as a foodplant.
Seven of the 52 highly reliant species are Nationally Scarce (three beetles, one fly and three micromoths); and three species are of Red Data Book status.
These figures are in general accord with those published by English Nature and Butterfly Conservation but are more stringently focused on species dependent on Ragwort. [Thus five Red Data Book species applies to species that eat Ragwort among a range of other plants (where available). The figure of 22 thrips is derived from earlier literature that does no accord with more recent specialist statements on Ragwort dependence.]
- Most breed in flower/seedheads or stems so Ragwort control by uprooting of flailing can destroy the required condition for these insects.
- In addition to those species feeding directly on Ragwort, the nectar in Ragwort flowers provides fuel for more than 117 species (English Nature figure). This includes:-
30 species of solitary bees, or more, utilise Ragwort.
Many hoverflies and other flies.
Butterflies by day, including the Small Copper.
Moths at dusk and during the night (e.g. 40 species of noctuid moths)
Two species of bee are particularly reliant on Ragwort as a foodplant.
- Additionally, many of the above insects have insect parasites. The exact number of species has still to be determined, but the reported 29 species falls well short of the likely true figure.
- Survival of such parasitic insects not only depends on continuity of the presence of plants in the right state year by year, but also on the presence of enough flowers/plants to support a viable population of the host insects.
- Ragwort is not just important for the invertebrate populations of SSSIs (Sites of Special Scientific interest). Many key pollinator species rely on the presence of Ragwort in the wider countryside to keep going when crops are not in flower. Also without nectaring sources in-between SSSIs the dispersal of nectar dependant species between sites would become harder.
- Disruption of continuity is a major reason why the fauna is already impoverished in many districts, for instance six species of bumblebee have declined in distribution by more than 95% in the last 25 years, largely as a result of the loss of flowers from the countryside.
- Invertebrates need a continuity of a reasonable quantity of Ragwort plants, and control should be limited to where it is strictly justified.
- Campaigns to eradicate Ragwort from whole districts, even where Ragwort is not a genuine problem to horses, threaten to exterminate 30 or more species of plant eating insects, and threatens the local viability of many more. This is at odds with Local Biodiversity Action Plans whose remit is to maintain biodiversity at local (and national) scales and does not comply with the Ragwort Code which requires risk assesments to be undertaken.
- In some circumstances Ragwort does need control but more widely the issue can be hyped-up to result in over-reaction. The purpose here is to look at the facts, especially in relation to the high profile concern over toxicity to horses.
- The toxins (pyrrolizidine alkaloids) in Ragwort can cause liver poisoning. It is a cumulative poison, eventually leading to the rather rapid onset of symptoms which precede rapid death. The plant has the alternative name Stagger Weed, referring to one of the more obvious symptoms. The lethal volume of Ragwort is said to be 7% of body weight for horses. Cattle are prone, sheep apparently less so (although it is difficult to find solid evidence of any fatal effects on other livestock). Young plants are less toxic than well grown ones.
- Ragwort poisoning symptoms are variable and resemble the symptoms of a number of other diseases and injuries. The number of deaths of horses in Britain due to Ragwort poisoning was 10 reported incidents in 1990 according MAFF published figures. According to the British Horse Society (BHS) the most recent figure is 6,500 per year with the situation getting worse.
Wildlife & Countryside Link (a consortium of most of the main voluntary conservation and countryside organisations, including Buglife) regards the statistical basis of the BHS/BEVA ragwort linked horse death analysis as falling far short of the necessary rigor. Moreover, there would appear to be no supporting evidence that there is a major problem in other western European countries.
- The British Horse Society (BHS) claim that 6500 horses are dying every year from Ragwort poisoning.
- However, Ragwort poisoning can only be confirmed by dissection of the liver.
- The BHS data is not based on confirmed data but the suspicions of vets. In addition, the statistical analysis is at best selective.
- The survey asked British Equestrian Veterinary Association (BEVA) members how many suspected cases of Ragwort fatalities they had seen in 2002. 4% of BEVA members responded saying on average they had seen 3.37 cases. The 3.37 was then multiplied by the membership of BEVA (1,945) to give an annual total of 6,553 cases.
- As anyone with a science degree will tell you, this is an absurd approach. In the first place, vets who did not encounter any Ragwort poisoning would be unlikely to respond to a survey about Ragwort poisoning as they would not consider it to be an issue. For all we know 96% of BEVA members may believe that Ragwort poisoning is an exceptionally rare factor in horse deaths.
- Therefore, a more honest reporting of the survey results would be that at least 283 horses were suspected of dying of Ragwort poisoning in 2002.
- However, in recent years there has been an increasingly vocal campaign against Ragwort, in many cases driven by those who would benefit financially from an increase in Ragwort control or monitoring.
- If you tell vets that hundreds of horses are dying every year from Ragwort poisoning they are more likely to suspect Ragwort poisoning as a cause of horse death. The more horse owners who ask vets ‘do you think it is Ragwort poisoning’, the more yes answers there will be.
- Therefore, one would expect a year on year increase in the numbers of suspected Ragwort associated horse deaths as a natural positive feedback loop.
Clearly any Ragwort poisoning death is a tragedy to both horse and owner. Undoubtedly some poisoning incidents in Britain can genuinely be attributed to Ragwort, but the scale of claimed incidents seems highly improbable.
- Horses are prone to Ragwort via two main routes.
– Grazing in fields containing Ragwort. Since the plant is toxic, horses will avoid the plant if possible; this is why Ragwort can reach pest levels of abundance on horse grazed pastures. The problem really arises where paddocks and fields are over-grazed, resulting in the animals being desperate enough to eat even toxic plants. Moreover, over-grazing opens up the turf to reveal bare ground which is ideal for Ragwort seed germination. To this extent, horse owners can generate the very problem that they wish to avoid. Cattle graze less closely and are rarely subject to such over-stocked conditions. In essence cattle and horses are able to co-exist with some Ragwort providing stocking levels are not overdone.
– The main, and more insidious, problem is the presence of Ragwort in gathered forage, mainly via hay. The plant is still toxic when dead, but horses are not so able to detect and avoid it. There are, however, two solutions. Hay from fields with Ragwort should not be fed to stock or horses. Where confidence is lacking, it is possible toss and shake through the hay to remove worrying material (it would seem that missing the occasional shoot should not be too critical).
- The most appropriate solutions to the problem of Ragwort poisoning are; firstly the proper implementation of Agriculture Act 1970 and Feeding Stuffs Regulations 2000 in which regulation 14 makes it an offence to sell feeding stuff contaminated with dangerous material; and secondly improved management of horse pastures, using established management techniques (e.g. rotation and reduced grazing pressure) to minimise the Ragwort content.
- A letter in The Sunday Telegraph (3 August 2003) by Frances Wolferstan BA, Vet MB, MRCVS, addresses what he refers to as ‘a nationwide outburst of hysteria’ towards Ragwort. He points out:-
– Horses and cattle will only eat distasteful Ragwort if they are half-starved on pasture that is bare of almost anything else.
– Even in the agricultural depression of the 1930’s and Second World War, Ragwort poisoning was not a major problem, yet working horses were in general use. In those pre-herbicide days, Ragwort was controlled by pulling, or using sheep to graze off young plants.
– No good stocksman would leave animals in a bare pasture with Ragwort. He felt it hard to believe that 6,500 deaths a year could be due to such a cause.
– Ragwort in hay is normally rejected by horses, and is easily removed by the groom or owner,
– The main problem could arise with silage incorporating Ragwort.
– He suggests that, in view of the high number horse deaths attributed to liver damage by Ragwort poisoning, it is time to look for other possible toxins. Pesticides added to grain to control weevils and mites is one possibility.
- A further worry is seed dispersal from ground adjacent to fields grazed by horses or used for hay to feed to horses. Though the seed is wind dispersed, a study showed that only 0.5% became airborne and that only a tiny fraction reached 40 yards from the parent plant even down wind (cited in Harper & Wood, 1957). Whilst one cannot conclude that seed never travels more than 40 m, there is seemingly no a need for extra wide buffer zones. Seed dispersing onto cropland will be negated by herbicides.
- It has been the case for many years that Ragwort has been controlled on some nature reserves. An excessive carpet of Ragwort over a wide area, especially of Common ragwort, is not desired by conservationists or farmers. In some instances the control by pulling or flailing may have been regrettably over-done, risking elimination of part of the special fauna (species that need stems, flowers and seedheads). But the principle of applying control where ragwort has become near dominant is well established.
- What is sought is a tolerance of Ragwort in locations and reasonable quantity where it is doing no real harm.
– On urban and rural uncultivated land.
– Road verges, bye-ways, even bridle-ways. In most circumstances horses are not going to stop to eat distasteful plants.
– In pastures which are not destined to reach the over-stocking level which may drive animals to eat even plants which are unpalatable.
– On land that has important Biodiversity associated with the Ragwort plants.
What is ‘a reasonable quantity’ of Ragwort? An inevitable question, but one with no neat answer since so much depends on local circumstances and the richness of the fauna. An annual appearance of 25- 50 decent sized flowering plants may be a fair minimum for bees, though more than 100 plants would be more viable for a self contained overall fauna within a few hundred yards or ‘a site’. The best faunal districts are likely to contain many more plants, often as a group of related smaller stands of Ragwort (supporting metapopulations of insects).
- The Ragwort Control Bill Act started as a Private Members Bill and has a curious history whereby Defra omitted to consult the conservation NGOs during the initial stages of the Bill. When objections were raised by Wildlife & Countryside Link, the momentum of and expectations for the Bill were running high. None-the-less, the Bill only got through its Second Reading through in the House of Lords by bringing in numbers of peers who probably would not have voted otherwise, and the Reading was then only passed when the wildlife amendments were withdrawn.
The objections centered on:-
- a) That Ragwort and its fauna is part of Britain’s wildlife and ought to be viewed positively.
- b) The claim that Ragwort was becoming more plentiful could not be substantiated since BRC data suggested otherwise. Hence, if there were a genuine increase in horse poisoning, there is no parallel underlying cause – i.e. an increase in the poisonous plant.
- c) The solution was better horse husbandry, including sensible care for grassland floras by not over-grazing and producing ragwort free hay crops.
- d) The data for numbers of horse deaths attributed to Ragwort poisoning was not statistically valid, both as regards data assembly and proof that attributed deaths were necessarily due to Ragwort poisoning as opposed to other causes with similar symptoms.
- e) Efforts at Ragwort control were likely to embrace other Ragwort species and other plants that could easily be mista ken for Ragwort by people lacking sufficient botanical knowledge.
Now part of our legislation, the Ragwort Control Bill is implemented through a Code of Practice that provides guidance on how to prevent the spread of Ragwort http://www.defra.gov.uk/environ/weedsact/default.htm
The Code states that ‘common ragwort and other ragwort species are native to the British Isles and are therefore an inherent part of our flora and fauna, along with invertebrate and other wildlife they support. The Code does not propose the eradication of common ragwort but promotes a strategic approach to control the spread of common ragwort where it poses a threat to the health and welfare of grazing animals and the production of feed or forage.’
The premature action by some County Councils (e.g. West Sussex County Council 2003) has already led to major campaigns to eradicate the plant from roadsides and many other places where genuine risk from poisoning may often be improbable.
- Just as horse owners have sought understanding of their genuine concerns, so to their understanding is sought of the biodiversity at stake. There ought to a compatibility of objectives if the need for Ragwort control is not over-played, and for that matter if the quantity of Ragwort for conservation needs is not over-stated. The objective is to ensure that in any district there is a place for both horses and the special wildlife of Ragwort.