Behaviour and risk assessment of fluopyram and its metabolite in cucumber (Cucumis sativus) fruit and in soil

Abstract

A field experiment was conducted to estimate residue persistence of fluopyram and its metabolite benzamide in cucumber fruits and soil and their risk assessment in humans and soil environment. Fluopyram (Kafka, 400 SC) was applied as soil drench twice at the interval of 15 days at the rate of 250 (standard dose) and 500 (double dose) g a.i. ha (active ingredient per hectare). Cucumber fruits were collected at 0 (1 h), 1, 3, 5, 7, 10, 15, 20, 30, 40 and 50 days after second application. Soil samples were collected on 15th day after second application. Drench application resulted in detection of residues on the third day in standard dose at the levels of 0.056 mg kg in cucumber fruit. The residue level increased until 20 days reaching 0.092 mg kg followed by decrease to 0.068 mg kg on 30th day after application. In double dose, the residues started accumulating from 0 day with initial levels of 0.093 mg kg and persisted until 30th day. The levels varied between 0.123 and 0.184 mg kg until 15th day of application followed by decrease to 0.127 mg kg by 30th day. The residues reached below determination level (< 0.05 mg kg) on 40th day in both the doses after second application. The residue of metabolite benzamide was below determination level (< 0.05 mg kg) at both the doses. Hazard quotient (HQ) for residues levels at 15th and 30th day was less than one (HQ < 1). Hence, a pre-harvest interval of 15 days is suggested. Present data can be used to establish maximum residue limit (MRL) in India. The residue of fluopyram in soil on 15th day and the data on soil adsorption coefficient of fluopyram from literature suggests moderate mobility of fluopyram in soil. However, residues of metabolite of benzamide were not detected in soil. Further studies on translocation of fluopyram in soil over the time can be conducted for better understanding of environmental risk. To our knowledge, this is the first report on residue levels of fluopyram in any crop when applied as soil drench.

From Old-Generation to Next-Generation Nematicides

“…Soil fumigants, which were mentioned briefly in this section and reviewed by several authors [8,10,11], are not discussed in this review. DT 50 (day) b) 7-17 [12] 4-25 [13,15] About 35 [16,17] log P c) 1.96 [12] 3.3 [13] Not available…”

“…However, fluopyram, like most other nematicides, moves a longer distance in sandy soil than in sandy loam soil [104], with a log P of 3.3 [13]. The half-life of the compound ranges widely under field conditions (3.8-24.8 days), probably depending on the soil type, concentration, and environmental conditions [15,92,105,106], in contrast to 64.2-93.9 days under laboratory conditions [86]. No relationship between its nematode-control efficacy and half-life has been reported.…”

Dissipation and residue determination of fluopyram and its metabolites in greenhouse crops

“…It as a systemic compound is absorbed through the leaves or roots and then distributed throughout the plant. [9][10][11] In consequence fluopyram can be moved easily into the edible portion of the crops which may pose a high risk to people on the basis of their potential toxicity properties. Moreover, once the pesticide is distributed throughout the plant, it degrades into several metabolites.…”

“…Open fields studies focus predominantly on the behaviour of the parent compound without taking into account the degradation compounds, 11,[16][17][18] although in one of them a single degradation compound was identified. 9 Also there is only one study conducted in greenhouse in which its degradation compounds were studied, 19 but the crop was in soil. Concerning PPP application techniques, most of the earlier-cited literature, deals with fluopyram foliar spraying on crops, except the study of Suchi Chawla et al, 9 where roots were drenched in the fungicide.…”

“…9 Also there is only one study conducted in greenhouse in which its degradation compounds were studied, 19 but the crop was in soil. Concerning PPP application techniques, most of the earlier-cited literature, deals with fluopyram foliar spraying on crops, except the study of Suchi Chawla et al, 9 where roots were drenched in the fungicide. The main objective of this study was to deepen knowledge about the dissipation of the fluopyram pesticide, including the transformation and behaviour of generated metabolites, in two important crops (cherry tomato and cucumber) under greenhouse conditions.…”