THE British Horse Society (BHS) claims that there are 6,500 horse deaths every year due to eating ragwort is still being contested.

On August 3 2003 the "Sunday Telegraph" published a letter written by Frances Wolferstan, BA, Vet MB, MRCVS, in which he heavily criticised the claims that 6,500 horses die each year due to eating the ragwort weed.

Here are some quotes from his letter: "I find it hard to believe that so many of today's horsemen and women leave their horses on bare ragwort-infested pasture that 6,500 animals succumb to ragwort poisoning...In the agricultural depression of the 1930s and during the Second World War there was far more ragwort around than there is today, there were also more horses in the country working on farms or pulling vans. Ragwort was a recognised disease, but not a major problem...I suggest that if 6,500 horses are dying of ragwort-like' damage each year, it is time to look for other possible toxins. Pesticides added to grain to control weevils and mites are certainly one possibility."

There have been emotive stories in the British Press about ragwort poisoning, calling it the "Yellow Peril", etc, and the 6,500 deaths is extensively quoted. However, these statements are at odds with the known facts. Examination of available evidence shows that it is extremely unlikely that this is the case. There are figures from a Government study for a period in the 1980s and 1990s involving cattle that shows figures in the 10-20 deaths a year range. Would it not seem curious if horse deaths were to be of a greater quantity? In fact, the plant is only toxic if eaten in large amounts, and there are studies that suggest it is less toxic to horses than it is to cattle.

Of course ragwort is poisonous. In the WHO study (EHC 80 Introduction p16). They say the damage is happening without sign or symptom. However, scientific statistics clearly show that it is not nearly the problem that press stories like to portray. It can cause livestock deaths, but this is comparatively rare and is usually as a result of eating ragwort in hay.

We must take care that we are not misled into making the wrong diagnosis which in turn could be harmful to the animals. Ragwort poisoning can only be confirmed by dissection of the liver. Apparently, BHS data is not based on dissection data, but the suspicion of vets.

The British Equestrian Veterinary Association (BEVA) carried out a survey where it asked its members how many suspected ragwort fatalities they had seen in 2002. Four per cent of BEVA members replied, who said that 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 6,500.

Ragwort (Senicio jacobaea) is a native British plant. There is a worry that it is spreading across the country like a plague. One reason given for the supposed increase of plant growth is that there has been a startling decrease in the number of cinnabar moths whose caterpillars eat ragwort. Evidence is firmly against this myth. Like all wildflowers ragwort is subject to regular surveys by botanists, and their conclusion after a recent survey, shows that there is no significant change in distribution since the 1960s.

Neither is it true that all landowners must by law control ragwort on their land. In the 1959 Weeds Act it does give the Government power to order a landowner to prevent some weeds from spreading. However, without such an order, there is no legal obligation on a landowner to do anything.

And, apparently, one of the most misleading stories is that a small amount of ragwort will kill a horse or a cow. Research shows that quite a significant amount of the weed would have to be consumed if it is to kill, and that amount can be up to 14 pounds in weight.

Professor M.J. Crawley FRS, at Imperial College, has studied the population dynamics of ragwort in his book, "Flora of Berkshire". He raises some debatable points.

"Research has shown that most of the commonly-adopted means of ragwort control have exactly the opposite effect to that intended. For example, pulling up ragwort by the roots leaves behind a ring of four or five broken root fragments, each of which is capable of producing a new rosette in the following year. So instead of reducing the pest, hand-pulling increases ragwort numbers four or five fold. Another method beloved of farmers (I suspect because it has such immediate and impressive visual impact) is to mow down the ragwort when it is in flower to prevent it from setting seed. A worthy aim, you might think. But what actually kills ragwort is setting seed, not mowing. If you prevent the plant from filling its seeds, then it retains its reserves in its root stock, and instead of dying, the plant survives to grow and flower again another year.

"Herbicides are effective, but they kill all the grassland herbs as well (the herbicides are selective only in the sense that they do not kill pasture grasses); Legumes, orchids and other attractive pasture species are lost under this regime. The Silwood research demonstrates that the best way to control ragwort is to fence against rabbits and then let the plants go to seed. Going to seed will kill the established ragwort plants and in the absence of soil disturbance and gap-creation by rabbits, the seeds will not produce ragwort plants. The strategy works because in a well-managed grassland, recruitment by ragwort is not seed-limited. Recruitment from seed requires competition-free microsites of the kind that are produced by cultivation or by heavy grazing from rabbits (or by over-grazing with domestic stock like sheep or horses)."

The expense of rabbit-proofing a field and leaving it empty of stock would not be a viable option for many of us. Pulling ragwort exacerbates the problem. Leaving the weed, risks poisoning the stock, and cutting are clearly not a solution. We seem to be left with herbicides. Ragtime is generally recommended for ragwort, but expensive; 5 litres costs about £30 and covers 200 square metres if used sparingly. It depends how many rosettes you're blessed with, and stock must be kept off the field for four to eight weeks after application, anyway. Some smallholders use sodium chlorate which has the same effect and they find much cheaper. A flame-gun is another solution, which is efficient and quick; once you have made the investment it can be used for years afterwards. The choice is yours.