The groundsel myth. It isn't better than ragwort!

This is one of my blog entries where someone has said something on twitter and it requires a longer response than can be posted on twitter.

It started with a very nice tweet.

    carl

    @carl90210_

    Potting up #ragwort for the cinnabar #moths and #solitarybees . I’m going         plant it all along the path in my lawn next spring, I’ll have a 9 metre ragwort         “hedge” ohh controversial #londonwildlifegarden #pollinators

In the replies was this tweet which contains a number of suspect claims.

Dunc

@FunktheDunc

 

Replying to

@carl90210_ and@lovely_plot

    maybe try Senecio vulgaris? same family, feeds the cinnabar moth and its             native too. Ragwort is a lovely plant but as you say controversial ( my                     daughter's pony died after ingesting ragwort )

 

Senecio vulgaris is groundsel and  the claim that his his daughter's pony was killed by ragwort is highly questionable. It is actually something that cannot be known scientifically.

Let's start out with this, "Cinnabar moths do well on groundsel" myth. It is a myth and we know the apparent source. Guess what? It is Professor Derek Knottenbelt again.Regular readers will know he is a source of a lot of the nonsense about ragwort.

Groundsel is a much smaller plant than ragwort. It can't support many caterpillars. It is also a more ephemeral plant. The issue about ragwort ISN'T the cinnabar moth it is all the other wildlife it supports. Groundsel is not a good nectar source. Ragwort is one of the best.

Some years ago there was an article in the Daily Post, a Welsh newspaper which said, 

 

        "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."

As I've said the moth isn't the issue,  but what studies? It is really annoying when a newspaper assumes because someone is  a professor they are supremely intelligent about everything and always know what they are talking about. He is NOT an expert on insect ecology!

I've already posted a debunk on my website here in my debunk of one of Knottenbelt's awful articles, which was full of errors!.

I will quote the debunk.

A research paper in the journal Entomologia Experimentalis et Applicata [3] studied the effects of three plants on the cinnabar moth. These were ragwort (S. jacobaea) groundsel (S. vulgaris) and coltsfoot (T. farfara) Here are the relevant results:-

Larval batches reared on S. jacobaea had significantly lower mortality (<1%) than those on either S. vulgaris (approx. 4%) or T. farfara (approx. 15%, which was also significantly greater than S. vulgaris)

So the caterpillars do better on ragwort. The paper goes on to talk about the egg laying preference of the adult moths.

Adults showed the same hierarchy of preference as the larvae, however they never oviposited on T. farfara.

This research clearly identifies ragwort as the best and most important foodplant. 

 Now let's deal with  the claim that a pony was killed by ingesting ragwort. First of all, the scientific literature is clear. Animals avoid the living plant unless they are cruelly starved into eating it.  Horses do get poisoned by eating contaminated hay but that is the responsibility of the hay maker and horse owner to deal with . It certainly isn't grounds for telling people not to grow the plant in a garden.

Secondly, it is well established that vets have been diagnosing any case of liver poisoning as ragwort poisoning without properly investigating. The British Horse Society once gave an account of a vet doing just that in their members magazine.

 In any case there is no test which can establish ragwort poisoning reliably. There are toxins that occur in mouldy food which cause exactly the same chemical damage. Their effects are indistinguishable.

Ragwort poisoning is actually rare.  Research by Professor Andy Durham showed that only a small minority of liver problems could fit the ragwort/mould catagory. He is the country's leading expert on this and he believes that we should stop talking about ragwort poisoning. Here is a short audio only video clip of him saying this. It is just 1 minute and 48 seconds long.