Systemic herbicide to combat annual grasses and broad-leaved weeds in maize. Mesotrione interferes with the biosynthesis of plasticin and carotenoids by acting on the 4-HPPD enzyme. S-metolachlor is absorbed mainly by the stem and coleoptilus and less by the roots. In weeds, the division of cells and the growth of shoots and roots are prevented. Terbuthylazine acts as an inhibitor of photosystem II of photosynthesis.