would like to try the washing up trick, how much do you use in a
sprayer?

I have successfully controlled horsetails by spraying with Roundup to
which washing up liquid has been added. The WU liquid reduces the
surface tension on the foliage allowing the spray to adhere to the
plant - and also produces foam (when sprayed) which is a good
indicator of which bits you have missed. It does take some time for
the effects to be seen and if possible, try to leave the fronds until
they have withered and gone brown.
On a really well established patch you may have some regrowth the
following year but a repeat treatment seems to see it off. Now is
definitely the best time to attack it while the growth is fresh and
lush.

--
ned



--
Jon Frohmaier