Posted: 20/04/2014 at 19:32
There are loads of different ones - use Google or ask at your garden centre and read the packs - they will tell you the contents and the concentration as well as recommendations and directions etc.
While real old fashioned creosote will kill virtually any plant, that's why it's no longer sold - it's dangerous stuff for humans too - the sort of product that gardeners sometimes refer to as creosote nowadays will not damage plants - that's why you can paint your fences without killing your clematis
There are also specific herbicides for roots and stumps - read the labels and get the right one and follow the instructions and you'll kill your tree stumps.
Brambles need to be sprayed with glyphosate when they are in active growth with lots of lovely fresh green leaves - I find SBK brushwood killer to be very good for this - RHS suggestions are here http://apps.rhs.org.uk/advicesearch/profile.aspx?pid=256