Abstract

Bioefficacy of imidacloprid against leafhopper, Amrasca devastans was evaluated on sunflower. Results of three season experiments revealed that seed treatment with imidacloprid 70 WS at 7g kg-1 protected the crop utpo 6 weeks against leafhopper. Foliar spray of imidacloprid 200 SL at 100ml hn-1 given at 3 weeks after sowing reduced the leafhopper population significantly and the effect persisted for 3 weeks. Imidacloprid 600 FS tested in the third experiments as seed treatment (5 ml kg-1) protected the crop upto 6 weeks against leafhopper. There was no reduction in the honey bee activity in these treatments when the crop was in full bloom. Significant increase in grain yield was observed in the imidacloprid treated plots. Germination was not affected by seed treatment and there was no phytotoxic symptom on the treated plants even when applied at a higher dosage. Residue of imidacloprid in seed and oil was at below detectable level at harvest when applied as seed treatment at 20 g kg-1 or as foliar spray at 400 ml ha-4.

Keywords: Imidacloprid, Sunflower, Leafhopper, Bloefficacy, Honeybee, Phytotoxicity, Residue analysis.