Neil Jones wrote:
The issue is more that when ragwort produces seed that seed travels
over a huge area and there are tens of thousands of viable ragwort
seeds produced by a single plant. If you're ragwort was guaranteed not
to spread beyond your garden owners of grazing animals wouldn't be so
worried about it.

Actually many many plants produce seeds like this. On average in the
long term one plant will produce only one offspring.

Statistically that's bit on the obvious side really isn't it! However
it's not to say that if you have a plant growing in an area that is
'good' for ragwort then you'll only get one plant grwoing the next
year.


Several studes have been carried out on ragwort. The most
comprehensive was carried out by scientists at Oregon State University
and published by The Ecological Society of America in their respected
scientific journal Ecology. It showed that, when tested in a variety
of conditions, 31% of the seeds traveled only 1 metre, 89% of them 5
metres or less and none were collected more than 14 metres from the
source. The study involved studying the dispersal of over fifty three
thousand individual seeds.

It'll still colonise a pretty wide area in not many years if left to
itself then. The other problem is that once you've 'had' it then
there are seeds on your land which remain viable for a long time.

As I've said before the real 'cure' on grazing land is to maintain it
well so that it's not very hospitable to ragwort. That's becoming a
bit difficult this year because it's so dry though and our pasture is
beginning to look much too bare to be 'ragwort proof'.

Thanks for all your input, it's interesting and useful. While I am a
horse owner and have land which does have a bit of a ragwort problem I
do think there's a fair amount of over reaction to it in the horse
world.

--
Chris Green )