Improved dissipation kinetic model to estimate permissible pre-harvest residue levels of pesticides in apples

Abstract

Prediction of residual concentrations of applied pesticides during the pre-harvest period may be required to ensure the safety of agricultural products. In this study, time-dependent dissipation trends of carbaryl (CB), kresoxim-methyl (KM), flubendiamide (FB), flufenoxuron (FN), bitertanol (BT), and chlorantraniliprole (CN) applied to apples at recommended and threefold greater doses were modeled to estimate pre-harvest residue limit concentrations (C) indicating permissible pesticide concentrations during the pre-harvest period. Double-exponential (DE) model results best fit the dissipation trends of all tested pesticides (correlation coefficients of 0.91-0.99) compared to zero-, first-, and second-order models. Among the pesticides examined, CB half-lives in apples of 2.9 and 6.6 days were the shortest, while those of FN (21.1-32.7 days) were the longest. The C values for each pesticide in apples were estimated with DE model parameter values and could be used to determine harvest dates for safe apples with pesticide concentrations below their maximum residue limits. Application of the DE model for C calculation provides more accurate information for farmers to produce agricultural products safe from pesticide residues.

Residue kinetics of neonicotinoids and abamectin in pistachio nuts under field conditions: model selection, effects of multiple sprayings, and risk assessment

“…However, goodness-of-fit indices such as r 2 and AKIE revealed a slightly better fit of the SFOK model compared to FODED (Table 3). SO and ZO models either overestimated or underestimated the dissipation data, as reported in previous studies (Hwang et al 2018) (Fig. 2, Table 3).…”

“…where C t is the concentration of pesticides (μg g −1 ) in pistachio nuts at time t (day), C 0 is the concentration of pesticides (μg g −1 ) after the uptake phase and the initiation of the dissipation phase, and k diss is the dissipation rate (day −1 ). For the FODED model, C 1 and C 2 are concentrations of pesticides (μg g −1 ), and k 1diss and k 2diss are the dissipation rates (day −1 ) for the fast and slow dissipation phases, respectively (Torabi et al 2017;Hwang et al 2018). DataFit version 9.1.32 was used to calculate all models and their parameters.…”

“…Therefore, the SFOK model was used to derive the dissipation parameters for IMI, THI, and THX. Similarly, most researchers have used the SFOK model to predict the dissipation kinetics of different pesticides in various plants (Torabi and Talebi 2013;Ugare et al 2013;Hwang et al 2015;Ramezani and Shahriari 2015;Chen et al 2016;Alister et al 2017;Hwang et al 2018). A few research have also shown the bi-phasic pattern of pesticide dissipation in plants (Utture et al 2011;Memarizadeh et al 2019).…”

“…Also, farmers usually apply frequent sprayings weeks before harvest depending on pest abundance, and it is not clear how these multiple sprayings affect the final pesticide residues at harvest time. Parameters obtained from statistical models would help predict pesticide accumulation/dissipation in pistachio nuts and their residues at harvest time under different multiplespraying scenarios (Torabi et al 2017;Hwang et al 2018;Lee et al 2019;Liu et al 2021). The model predictions are used subsequently to conduct pesticide risk assessments for humans via the consuming pistachio nuts.…”

Dissipation of fomesafen in fumigated, anaerobic soil disinfestation‐treated, and organic‐amended soil in Florida tomato production systems

“…Based on data modeling methods suggested by Hwang et al ., time‐dependent dissipation trends for fomesafen residues in tested soils ( C ( t ) ) were assessed for goodness‐of‐fit using zero‐, first‐, second‐, and double‐exponential kinetic models as shown below: C ( t ) = C 0 − k z × t (zero order, ZO) (first order, FO) (second order, SO) (double exponential, DE) where C 0 is the initial concentration of fomesafen in soils (ng g −1 ), and k z , k f and k s represent the zero‐, first‐, and second‐order rate constants (days −1 ), respectively, for the dissipation models. Herbicide dissipation by the DE model is assumed to have fast and slow phases proportionally represented as P 1 and P 2 , and summing to 100%.…”