Standard commercial spray mix. This is for a 15L mix but you can adjust as necessary.
Half fill a Croplands Swissmex 15L Knapsack Sprayer with water.
Add 200ml of Glyphosate 540
1-2 capfuls of Brushwet (wetting agent)
1-2 capfuls of Envirodye (usually blue)
and the secret weapon: 1-2ml (measured carefully in a syringe) of Hammer (Carfentrazone-Ethyl) to really knock stuff on the head.
Continue filling the sprayer with water and add a few drops of de-foamer if necessary.
Spot spray only to the point of run-off. Hammer has enough power to kill neighbouring shrubs so use caution.
There is a company called Apparent which makes generic versions of all these chemicals.