Pesticide Residue Laboratory Department of Agricultural Chemistry and Soil Science, All India Coordinated Research Project on Betelvine, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur-741 252, Nadia, West Bengal, India.
Online published on 31 October, 2011.
A field study was conducted with chlorothalonil (Kavach, 75 WP) in/on betelvine to examine its persistence behaviour. Chlorothalonil was applied four times in the vine in two doses 2.5 g I−1 (T1) and 5 g 1−1 (T,) by soil drenching at an interval of 30 days. The residue of chlorothalonil in leaf samples on the 5th d after 4th application was found to be 0.608 and 1.062 ppm in T1 and T2 which dissipated to about 95–98% after 30 d of application. In soil, the initial deposit was found to be 3.856 and 7.928 ppm in two doses which diminished by 98% and 99% after 30 d of application. The 10 g concentration of residue was found to be linear with time, and t1/2 values calculated at lower and higher doses were 4.62 and 6.02 d in leaves and 4.70 and 5.37 d in soil, respectively. The waiting period was calculated as 8.50 d and 9.37 d, on the basis of tolerance limit of chlorothalonil (5 ppm) in leafy vegetables.
Chlorothalonil, betelvine, half-life, residues, waiting period, dissipation, reaction kinetics
