As is often the case today's blog entry is based on something happening on Twitter. In this case this rather amusing but accurate tweet by Bill Ellson.
It gives me chance to express my honest opinions based on approaching two decades of detailed research.
Indeed, there are many crazy claims made about it spreading. One of my colleagues once sent out a message advising people to help me and jokingly suggested that there were so many silly claims that ragwort might be blamed for the fall of the Roman Empire.If ragwort spread at the rate some people claim the British Isles would have sunk under the sheer weight of the stuff some years ago.
This brings me back to an article I recently discovered by the influential Professor Derek Knottenbelt.
He has been influential in the spread of the hysteria around ragwort and you will remember that I wrote about his insane claim that the plant was causing the decline of the Cinnabar Moth which actually relies on it for food.
Well, the article which I used to confirm that story is a real gold mine. I could blog about it for weeks. I collect Knottenbelt's writing avidly, for not only is he the source of a lot of the problems, but his writing about this subject is really wildly wrong.
It is, in any case, always a good idea to examine the views of the best of those opposed to your view as it guides against error. So I do try to do this. The problem is that my opponents in general are sometimes so desperately awful that it is really hard to find anything challenging. Just look at what I have written in the past about the British Horse Society!
At this point some people will say who am I to challenge a professor? How can I understand or evaluate such a high standing expert?
The answer comes from one of the greatest geniuses of the 20th century ,the Nobel Prize winning physicist Professor Richard Feynman. He sums this up in a famous quote during one of his recorded lectures. He was talking about the derivation of knowledge about the laws of physics but the principle applies to all of science.
“If it disagrees with experiment, it is wrong. In that simple statement is the key to science. It doesn't matter how beautiful the guess is. It doesn't matter how smart you are. Who made the guess . What his name is. If it disagrees with experiment, it is wrong. That is all there is to it.”Indeed, using arguments from authority is one of the biggest errors it is possible to make in science. Only the facts make something true, not who said them. Furthermore, people who have authoritarian tendencies have been studied clinically and shown to have deficits in mental processing that inhibit logical thinking.
Coming back to the point about the exaggerated claims about ragwort spread. This is a quote from Professor Derek Knottenbelt in the article which I found.
" It produces more than 150,000 seeds, with an expected germination of more than 80% for up to 20 years."Now here we have a prime example of how panic is generated. This is at best highly misleading if not definitely untrue. That 150,000 seeds figure was used in advertising by an equine charity. I complained to the Advertising Standards Authority (ASA). The figure being used was an exact 150,000 not "more than", which is worse of course. The ASA, who are of course independent, banned the advert as misleading. Now we seem to know , yet again, that the story comes from Professor Knottenbelt.
80% is a normal germination rate for many flowering plants but of course such a high figure being mentioned sounds alarming. It is pretty much irrelevant in telling you anything about the rate or degree of spread. On average a plant produces one offspring, and produces enough seeds to ensure this. Then "up to 20 years",is that true? Well it is rather suspect. Most of the research shows a much lower figure. There is a study using an unusual soil type where it is extrapolated that 1%, just 1% , of the seeds might survive.
It is interesting to note that later in the article Professor Knottenbelt uses this wrong figure again.
Of course this is wrong, but you can see how horse owners would be panicked by this.
"The BHS and DEFRA offer leaflets giving advice on methods of removal -- but all we need to remember is that every plant that is left to seed this year can produce another 150,000 plants over the next few years. "
Another interesting and wildly wrong statement is this:-
Just imagine the panic this sort of thing causes among horse owners. We have an equine veterinary professor telling them there is a 1 in 5 chance that their horse is suffering from poisoning that could kill it. It would be unnecessary panic because this claim by the professor was hyperbole. The facts showed it was wrong by a massive amount.At Liverpool University we have a research group developing a non-invasive equine blood test, to be used as an early indicator of ragwort poisoning before the clinical signs develop. I estimate that 20% of horses in this country will have ragwort poisoning in their body.
They did do the the research. A PhD student was given the task of doing it. Given the amount of work I do on this you would expect that I would know all about this research and I do. I have a copy of the thesis.
This test never really worked as expected although the biochemistry seems sound. If horses really had eaten ragwort the signs should show in the blood. A student was given the research task for her PhD.
What you have to realise at this point is that ragwort poisoning is difficult to diagnose. It just shows up as liver damage, which can have many causes. Other more recent and separate research has shown that only a minority of these might be ragwort. We have to say might because although there are characteristic microscopic changes in the liver, which you can see by taking a biopsy, these changes can also be cause by toxins in mouldy feed.
In the research for the PhD ninety one horses that had signs of liver damage were tested. Only one , a case were a horse had been mistreated, showed a positive result. Note, these were not the general population about which the wild claim that 20% of them would have positive signs of poisoning. These were sick horses already showing symptoms and yet no sign of ragwort poisoning could be found except in a case where the horse had been mistreated.
The article goes on and on with poor information.He uses the infamous survey claiming thousands of horse deaths as if it is accurate. The statistics are really very obviously crooked talking a minute response rate and multiplying it as if everyone had replied. Adverts using it were again stopped after action by the ASA. Surely a professor should recognise such misuse of statistics?
He gets the law badly wrong, as he has on other occasions.
Classified as a noxious weed in the Weeds Act of 1959, every landowner has since been required to control ragwort either by direct spraying or by lifting and burning.
Again adverts making the same false claim were stopped after ASA action. Every landowner is not required by this act to control the plant. Incidentally the word noxious isn't even in the act!
He makes this ridiculous claim:-
"Until the last decade, ragwort was not widely seen"There is a botanical recording scheme which shows that its distribution has not changed since at least the 1960s and a few years after this article was published government research actually showed that ragwort had been declining in abundance.
It should be obvious to anyone why I honestly have a problem believing anything this man says.
