Long Lasting Weed Killer

[TrudyTrudy]

Can anyone recommend a long lasting weed killer that actually works? I have tried a few without much success - was told to try an 'industrial strength one' but other than that I am at a loss...any suggestions.

[AlBags]

There are not really any with any strength around these days, due to the contamination of water table and land.
Most deactivate when they hit the soil, so you should use when there is plenty of green matter to spray.

[Count-A-Strong]

You need to check that the one you buy is 'systemic'

[Hawkwalk]

Resolva is very good. It works as a systemic and contact so a double hit and I find it is very quick