Sena wrote:

said...
I wasn't at all cheered by reading that some
unnamed scientific hooligans only managed to kill 75% of a sample of
cattle by feeding them 0.6% of their body weight of fresh ragwort a day
for 20 days: in the dried form, that would be quite a small amount --
perhaps something like the volume of a packet or two of tea -- and
might well escape the stockman's detection. The way the result was
quoted represented the dose as very large, and appeared to be an
attempt at reassurance.


It certainly didn't reassure me. I wondered, as I read that bit and the
bit about the horses, just who had provided the money for such wanton
slaughter. Or do we (generic) then feed ragwort-ridden cattle to animals
in the form of 'my little cat food'?


Cruel the studies may be but that doesn't affect the accuracy of the
conclusions. There is no risk at all to animals or humans from eating the
very rare examples of cattle that are poisoned because the poison is
actually destroyed when it does its poisoning. It does not accumulate in
the animals system. The effects do, but these only occur, as I have said,
above a series of biochemical thresholds.


Neil Jones
http://www.butterflyguy.com/

Neil Jones wrote:
Mike Lyle wrote:
[...]
As a sometimes enthusiastic revisionist about many things, I agree it's
an interesting site; but it doesn't seem to quote very many papers, and
it certainly doesn't deny the toxicity of these plants.


There is an abvious logical flaw in what you are saying. Just because a
website says something that a lot of other websites do not say does not
mean it is wrong. It is the scientific facts that count. There actually
isn't a lot of study that has been done so the fact that ony a few papers
are quoted does nothing to undermine credibility,

I detect no logical flaw in my comments. You will note that I do not
challenge the three (I think) papers quoted on the site, which agree
with my other reading or, in the case of seed distribution, my informal
personal observation. My impression is that there's been a lot of study
over the years.


RAgwort poisoning is actually very rare, but certain people have made a big
fuss and misused statistics in a very very unethical way to mislead people.
We know it is very rare because internationally there are a set of
scientific papers that say this.
You find for example that someone has written a scientific paper in Holland
because of a poisoning incident, caused incidentally by gross stupidity,
and that it is interesting because a case hasn't been reported in years.
The French looked into it and couldn't find a case!

It's rare because farmers take the usual precautions. In fact,
poisoning by plants in general is rare. That doesn't make it unreal.

You don't want
them in hay or silage.

That is the only place they cause problems and then only if there is
sufficient.

That's broadly true, which is why I said what I said. There are
recorded cases of poisoning by fresh material, though: for an extreme
example, Forsyth in HMSO 161 reports personal observation of the whole
course of an outbreak in a flock of 140 ewes in Iraq.

[...]

Small doses will cause ZERO damage because of a whole series of biochemical
thresholds which have to be exceeded before any damage is done to the animal
at all. The compounds in Ragwort are actually non-toxic and have to be
converted before they can cause damage.

But I understand that the hepatotoxic alkaloids in ragworts do act
directly on the viscera. It's true that death results from the liver
damage after the toxins themselves are no longer present in the
affected animal, but this is neither here nor the the damage is
done.

[...]

Of course people shouldn't panic about the ragworts; but they _are_
toxic, and they aren't endangered, so getting them out is generally a
good idea, especially in fodder crops. Even if one has no susceptible
stock, I think it's reasonable to be a good neighbour to others,
[...]

As an entomologist I know there is a basic rule. ALL plants contain toxins
of one kind or another. Brassica poisonging and Onion poisoning are both
well known in livestock. Brassicas contain allyl isothiocynate and the
lethal dose of that in cattle is around 0.001% of body weight.

Which is why farmers take precautions. I think the maximum ration of
kale is about 15-20kg/day.

The environmental effects of such a law could be disastrous. People
removing bluebells and foxgloves because they believe it is demanded by
law. Imagine having to destroy all those woods full of wild garlic. Oak
trees are mildly poisonous too! We already have people believing that you
have to control ragwort by law which is not the case.

And, of course, to quote you above, "I shan't name them because I don;t
want to start another bout of hysteria"...

You'll forgive me, I hope; but it really does seem that when somebody
comes along and broadly agrees with your substantive point, it just
isn't good enough for you. You seem to want to be agreed with word for
word on the details: I'm afraid I can't oblige.

--
Mike.

What about applying weedkillers? How long should I keep guinea pigs off a lawn treated with weedkiller?

Cheers, Dave.