Royachlor (Butachlor 50% EC) is a selective pre-emergence systemic herbicide used mainly in rice (paddy) to control annual grasses and some broadleaf weeds. It is absorbed by germinating shoots and roots, preventing weed growth during early crop establishment. Apply within 3–4 days after transplanting or sowing on moist soil for best results. Use in accordance with product label and applicable safety regulations.