Behaviour of fenitrothion residues in leaves and soil of vineyard after treatment with microencapsulate and emulsified formulations

Abstract

The rate of decline of fenitrothion residues was investigated in leaves and soil of vineyard over 2 months after treatment with two different kinds of commercial formulations: emulsifiable concentrate (EC) and microencapsulate (ME). Fenitrothion residues were determined with GC-NPD after acetone extraction of soil and leaves. The measured initial deposits in soil and leaves varied between 2.6 and 3.8 mg kg À1 and between 89 and 101 mg kg À1 , respectively. Fenitrothion residues in soil dropped at 0.1-0.2 mg kg À1 after 60 days following application with EC formulation showing a more rapid decline than the ME. Fenitrothion residues in leaves from ME formulation treatment showed a longer persistence and lower decline rate than those from EC formulation. During the experimental period, fenitrothion remaining in leaves from ME application was 10 times more than from the EC one. Mathematically defined decline curves were established by determining optimal relationships between fenitrothion residues and time. The RF1st-order and RF1.5th-order equation achieved the best adjustment to the experimental data of fenitrothion dissipation on leaves for the ME and EC formulation, respectively, giving fenitrothion half-lives of about 2-3 days for ME and <1 day for EC formulation. In vineyard soil, the best adjustment to the experimental data for ME and EC formulation was achieved by the 1st-order and 1.5th-order equations, respectively, giving fenitrothion half-lives in soil of about 17-21 days for ME and 5 days for EC formulation.

Comparison of Dissipation Kinetics and Residual Behaviour for Fenitrothion Insecticide and Thiobencarb Herbicide in Clay Soil

“…The recovery percentages were 85.69 for fenitrothion and 90.89 for thiobencarb in clay soil. These results confirmed by Likas and Tsiropoulos (2007) who found recovery of fenitrothion was 94±10% in soil by GC and Redondo et al (1994) who found the recovery of thibencarb in soil 63%. Similar carbamate recoveries were obtained from soil samples using liquid-liquid extraction with methylene chloride (Redondo et al, 1994).…”

“…Fenitrothion degraded in upland and submerged soils with the half-life of less than 7 days and was of shorter persistence as compared with its half-life of 12-28 days under upland conditions and less than 14 days under submerged conditions found by Takimoto et al (1976). Fenitrothion half-lives in soil of about 17-21 days (Likas and Tsiropoulos, 2007). Studies carried out by Sundaram et al (1987) and Sundaram et al (1989) showed that the amount of fenitrothion deposited on soil dissipated quickly.…”

“…To evaluate the decline of fenitrothion and thiobencarb residues in soil, residue data should be subjected to statistical analysis to determine the statistical parameters that describe these processes, as proposed by Likas and Tsiropoulos (2007). Two methods were used to determine the best kinetic model for the dissipation data, graphical and integral methods.…”

Degradation Kinetics and Half-Lives of Fenitrothion and Thiobencarb in The New Reclaimed Calcareous Soil of Egypt Using GC-MS

“…Similar carbamate recoveries were obtained from soil samples using a traditional method involving liquid-liquid extraction (Leppert et al, 1983;Szeto and Sundaram, 1980). The recovery percentage of fenitrothion in soils was 94±10% (Likas and Tsiropoulos, 2007) also, in soil it was 98% (Roy et al, 1996). The non-extractable residue might be attributed to the formation of the soil-bound residue (Scheunert, 1992), its percentage ranged from 7 to 90% based on the applied pesticide (Khan and Dupont, 1987).…”

“…To evaluate the decline of fenitrothion and thiobencarb residues in the studied soils, residue data should be subjected to statistical analysis to determine the statistical parameters that describe these processes, as proposed by Likas and Tsiropoulos (2007). Two methods were used to determine the best kinetic model for the degradation data, graphical and integral methods.…”