Chris Wilson wrote:

I am in Shropshire, England. Last year I sprayed a large swathe of nettles
and brambles on 7 acres of field and woodland we bought. I have knocked 7
bells out of the brambles, the nettles didn't suffer as much. I want to
finish them off this year, when's the best time to spray please? What's the
flavour of the month in regard to stuff to use, I don't want to kill grass
or ferns, if possible? I'll be using a comapct tractor spray and a back
pack spray. Thanks.

Chris, have just found good advice amongst the information on the
following page. In short, it advises spraying with glyphosate when the
weeds are 6" high and spraying onto dry weeds and at the beginning of a
fairly lengthy rain-free period.

http://www.ag.ohio-state.edu/~news/story.php?id=3604

Eddy.