Persistence and dissipation of quinalphos in/on cauliflower and soil under the semi arid climatic conditions of Karnataka, India.

Persistence and dissipation of quinalphos residues in/on cauliflower was studied after giving spray applications at 2 concentrations, i.e. recommended dose of 500 g a.i. ha(-1) and double the recommended dose of 1,000 g a.i. ha(-1). Residue analysis of cauliflower curds was carried out after the third spray over a period of 15 days. Initial residues of quinalphos on cauliflower from the two treatments were 1.19 and 1.842 mg kg(-1). The residues persisted up to 15 days from both the treatments. The residues of quinalphos dissipated from both treatments with the half-life of 4.8 and 5.3 days. Based on the persistence study and maximum residue limit value of 0.05 mg kg(-1) the safe pre-harvest interval was worked out as 17 and 22 days from treatment at the recommended and double the recommended dose, respectively. Analysis of soil samples was carried out on the 15th day of sampling and residues were found to be 0.013 and 0.044 mg kg(-1).