Persistence of mancozeb residues in papaya (Carica papaya)

Abstract

An experiment was conducted during 2005 to study the persistence and dissipation of Mancozeb during fruit growth stage of ‘Arka Surya’ papaya (Carica papaya L.). Treatment spray application of Mancozeb (Bilzeb 75 WP) was given 3 times at 15 days intervals at the recommended and double the recommended dose of 2 and 4 g/litre, respectively, commencing from 26 June 2005 at fruit growth stage. Very high initial residue deposits of 8.1 and 17.72 mg/kg of mancozeb (as CS2) was recovered from whole papaya fruits at recommended and double the recommended dose, respectively. Residues dissipated very fast and after 1 week of treatment it was 1.87 and 3.7 mg/kg only. At harvest (30 days after the last spray) the residues had reached below the detectable level of 0.1 mg/kg from recommended dose of treatment, whereas at double the recommended dose it was 0.15 mg/kg. The half-life of mancozeb residue was found to be 3.9 and 4.6 days. Based on the maximum residue limit value of 3.0 mg/kg (as CS2) (Codex Alimentarius) the preharvest interval or waiting period for recommended and double recommended dose of mancozeb treatment was 4 and 8 days, respectively