Professor Derek Knottenbelt is a veterinary expert who has received a lot of publicity for his comments on ragwort. Many of his comments seem rather highly questionable and some examples are included below. It should, of course always be remembered, that since these are press comments they may not exactly reflect the words that he used, but they are seem to be consistent very often with what he has written himself.

QUESTIONABLE COMMENT: There has been an explosion of ragwort in the past five years. "One can hardly avoid seeing it along roads," he told the equine council in a speech. "The yellow peril is lurking, and expanding its grip on the UK."
SOURCE:Guardian, Monday, August 26, 2002
FACTS: A government scientific survey including this period showed a very significant decline in ragwort.

QUESTIONABLE COMMENT: Dr Derek Knottenbelt,who heads the project, estimates that around 500 horses and ponies died of liver failure due to ragwort poisoning last year. With the increasingly widespread distribution of the plant, he suggests that this year the total number of equine deaths from ragwort poisoning may reach 1,000.
SOURCE: Malton Gazette & Herald Wednesday, February 11, 2004
FACTS: He later published his statistical method for working this out and it seems very very questionable see: Professor Derek Knottenbelt Yorkshire Post. Advertisements making similar claims were stopped after action by the Advertising Standards Authority

QUESTIONABLE COMMENT:Professor Derek Knottenbelt of Liverpool University, a world expert on ragwort , has warned that unless it is eradicated soon humans will start to suffer as the toxin enters the food chain. He said: "It is an environmental catastrophe waiting to happen and it is happening right in front of our eyes."
SOURCE: Daily Mirror Monday, September 12, 2005
FACTS: Ragwort in the food chain has been looked at, and not found to be a problem. Also see Ragwort and meat for an explanation of why it isn't a problem there.

QUESTIONABLE COMMENT: "It is toxic to humans, so what the hell are we doing with it in this country?"
SOURCE: Several sources including Coventry Evening Telegraph Wednesday, May 3, 2006
FACTS: Many many plants are poisonous to people, including parts of plants like the tomato, potato and runner bean. Ragwort is not particularly dangerous to people and there seem to be no documented cases of anyone in the UK ever being poisoned by it. It takes a large dose to do any serious damage.

QUESTIONABLE COMMENT: Prof Derek Knottenbelt , of Liverpool University, believes everyone has a responsibility to tackle the "hooligan weed" - and said conservationists may be wrongly sheltering the plant to protect the cinnabar moth. His own studies have shown populations of the rare moth have plummeted as ragwort spraying has fallen, and suggests the moth feeds better on groundsel.
SOURCE: Daily Post North Wales Edition Thursday, April 29, 2010
FACTS: The issue over ragwort isn't over the cinnabar moth. It is an important nectar source for many insects. Groundsel is an inferior food source as it is smaller and less likely to persist over a period of time. Research shows that the larvae develop less well on groundsel and that the adult moths prefer to lay their eggs on ragwort. (Tinney, G. W., Hatcher, P. E., Ayres, P. G., Paul, N. D., & Whittaker, J. B. (1998). Inter- and intra- species differences in plants as hosts to Tyria jacobaeae. Entomologia Experimentalis et Applicata, 88(2), 137-145.)

QUESTIONABLE COMMENT: he added: "No one has considered the implications on meat and other animal products of using sheep or cattle to "clean out" a field of ragwort ."
SOURCE: Daily Post North Wales Edition Thursday, April 29, 2010
FACTS: It has indeed been considered and dismissed. The standard textbook, Chemistry and Toxicology of Pyrrolizidine Alkaloids written by an expert from the Toxicology Unit of the Medical research Council Laboratories some years previously, covers this issue See Ragwort and meat

QUESTIONABLE COMMENT: He told the conference he had poisoned himself with ragwort to disprove critics who had claimed it was harmless to humans, adding: "My liver is in a bad state."
SOURCE: Express on Sunday Sunday, April 30, 2006
FACTS: It seems very puzzling why he did this. There is no debate about whether people can poison themselves with ragwort. People don't eat it so they don't get poisoned. If what the professor says about ragwort elsewhere is true then he has damaged his own liver for no need.

QUESTIONABLE COMMENT: He said the poisonous pyrrolizidine alkaloids (PAs) contained in ragwort could spread to humans through several routes ...... In South Africa they had been found in bread, possibly through ragwort growing unseen among crops and being included in the flour.
SOURCE: Western Mail March 28 2006
FACTS: The organisation that holds the records for plant occurrence in South Africa say that they have no record of the plant growing there. See Ragwort South Africa Myth

There is also the quote with a claim that the Cinnabar Moth, for which ragwort is the main foodplant is being poisoned by the plant, which seems utterly crazy. See Ragwort does not poison the cinnabar moth

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Professor Derek Knottenbelt.