[Marshlady]

I have a lovely old pasture on which to graze my 5 Jacob's and 2 Texel crosses. One part of it - from which they are currently excluded - has mares' tail in it, I have heard that it can be poisonous, is this true?

[doganjo]

This might help, I don't see it mentioned here but it might be under a different name.
http://www.ttlntl.co.uk/2/Health/poisonplants.htm

[Jackie]

Well its not poinonsous to humans as you can supposedly make tea from it, although I have never tried.

[Canadian Sheepfarmer]

Old farmers used to say that this prehistoric plant was poisonous but my sheep would never eat it, I suppose if they were starving and there was nothing else they might nibble at it but I never found it a problem. It is a very hard one to get rid of especially organically.
Glyphosate might do it with a weed wiper?

[shetlandpaul]

you have to damage the silica coating before spraying. its ment to be bad for horses but why they would want to eat it is another matter.

[shrekfeet]

no plant can stand being constantly stripped of its foiliage. Just keep mowing it off and it will soon die