Persistence of bifenthrin residues on apple (Malus domestica) fruit and soil.

Persistence of bifenthrin (Brigade 8% SC) was studied on apple fruits and tree basin soil following foliar application @ 60 g a.i./ha and 120 g a.i./ha on fruit bearing trees at two locations viz. Solan and Mashobra for three consecutive years 2003–2005. The residues of bifenthrin were estimated by using Agilent 6890 N Gas Chromatograph equipped with ECD and NPD. Initial deposits of bifenthrin were in the range of 0.669–1.062 mg/kg at 60 g a.i./ha dose and 1.348–1.784 mg/kg at 120 g a.i./ha dose which reduced to half in 4.85–5.22 and 4.38–6.66 days at the respective doses. In tree basin soil, on 0 day the bifenthrin residues were 0.126–0.153 mg/kg and 0.521–1.263 mg/kg after spraying of respective doses which were reduced to 0.054–0.093 mg/kg after 30 days. Based on the Maximum Residue Limit (MRL) value of 0.5 mg/kg of bifenthrin on apple, a safe waiting period of 2.1–5.4 and 6.7–11.3 days was worked out for respective treatments.