Dissipation of endosuifan residues in kharif paddy under West Bengal agroclimatic conditions

Abstract

Field trials were conducted during the aman season to understand the dissipation rate, half‐life and T_MRL values of endosuifan 35e.c. in soil, green foliage and green grain following application in the flowering stage of paddy with the recommended dose (005% @ 500 litres/ha) and double the recommended dose (0.10% @ 500 litres/ha). The maximum residues on soil after 7 days of application (0.029 and 0.092 ppm) were well below the tolerance limit of endosuifan (0.1 ppm for rice in husk). The initial deposits varied from 4.571 to 11–671 ppm for green foliage and from 1.778 to 4.274 ppm for green grain. Dissipation followed a first order reaction in all cases and the half‐life values varied from 3.3 to 3.4 days for green foliage and from 5.6 to 5.7 days for green grain. Calculated waiting periods (T_MRL) varied from 19.3 to 23.7 days for green foliage and from 22.5 to 29.9 days for green grain. The terminal residues of endosuifan at harvest in different substrates varied from 0.007 to 0.042 ppm, well within the prescribed tolerance limit.

Keywords:

• dissipation
• endosuifan
• grain
• half‐life
• paddy
• residue
• soil
• straw
• waiting period