Make sure the docks are at the correct growth stage - the rosette stage - in order for them to take in the chemical properly and for it to translocate down into the roots. If they are too big then cut them and treat the regrowth, usually 2-3 weeks later.
Apply at the rosette growth stage, before the docks are 150mm to 200mm high or across
Weeds must be actively growing; free from disease or insect damage; not suffering from drought, waterlogging or nutrient deficiency
Hand held application only via a hand held lance on a quadbike or via a knapsack