Terminal Residues of Butachlor and Pendimethalin in Onion

Terminal residues of butachlor and pendimethalin, applied as pre-emergence at 1.0 kg ha⁻¹ in direct seeded onion crop, were investigated in green onion, dry onion bulbs and soii samples under rield conditions. Representative onion samples were drawn at 50 days (green onion) and at 129 days (mature onion bulbs) after application and analyzed by GLC-ECD. The residues of butachlor in soil, green onion and mature onion bulbs were as 0.015, 0.007 and 0.002 μg g⁻¹, respectively. Green onion contained 0.003 μg g⁻¹, of pendimethalin residues, however soil and dry onion bulbs at harvest were free from any residues. The study indicated that terminal residues of butachlor and pendimethalin applied in onion were well within the safe limits (0.025 μg g⁻¹).