Efficacy and residual toxicity of some systemic granular insecticides againstthrips tabacion onion

Field trials were conducted during 1980 and 1981 to evaluate the systemic granular insecticides disulfoton, phorate, carbofuran, aldicarb and bendiocarb against Thrips tabaci Lind. on onion. Residues in plants at different intervals and in bulbs were determined by gas‐liquid chromatography. Carbofuran at 1.0 kg a.i./ha was most effective, followed by phorate at 1.5 kg a.i./ha. Carbofuran persisted in plants for up to 23 days after application, while phorate was readily translocated and gave effective initial control. No residues were detected in fully mature bulbs 75 days after application of the insecticides. For green onions, a waiting period of ten days is suggested.