Brambles
(Rubus fruticosus), stinging nettles
(Urtica dioica) (right) and creeping thistles
(Cirsium arvense) are all nuisance perennial
weeds that can quickly colonise neglected ground.
Contact herbicides give very little control - simply scorching the foliage - as these weeds all have the ability to regenerate new top growth from their perennial root system.
Consequently systemic weedkillers that travel down into the roots of the weeds are recommended for the control of these persistent weeds. The most effective are based either on glyphosate (Roundup Tree Stump & Rootkiller, Deep Root Ultra Tree Stump & Weedkiller) or triclopyr (specifically SBK Brushwood Killer).
Each of these active ingredients has their own properties. For example, glyphosate is non-selective whereas SBK Brushwood Killer is harmless to grass. Additionally, glyphosate doesn't linger in the soil whereas SBK Brushwood Killer remains in the soil for six weeks. Check the manufacturer's recommendations for individual herbicide properties and methods of application.