The process of winter cleaning pastures
Simazine remains effective in the soil for 6–12 weeks. Shorter residual periods occur under conditions which favour greater biological activity, such as soils with high organic matter, good moisture, good fertility and warmer soil temperatures.
Plants begin to yellow and appear burnt at the leaf tip. Under favourable conditions the target plants start to die 2–4 weeks after simazine application, but quicker if paraquat is also applied. Paraquat can result in sub‑clover leaf damage but the leaves will recover.
Same plot, pre-treatment in late July (left) and 14 days later (right) after the applications of simazine and paraquat