**4. Conclusions**

This study investigated the residue pattern of fluopyram, in terms of the bioconcentration factor, in soil and its uptake by scallions during greenhouse cultivation. Residues in the soil and scallions were measured using a modified QuEChERS method coupled with HPLC-MS/MS and validated according to the European SANTE/12682/2019 guidelines. Fluopyram residues in soil showed limited dissipation during cultivation, with a DT50 of 87–231 days. The DT50 values were found to be higher than that reported for other crops in the previous literature, indicating that fluopyram may be a persistent pollutant in the environment. Fluopyram in soil was taken up by scallions through the roots, but residual levels in scallions during cultivation decreased due to an increase in plant weight, which caused a dilution effect. The peak BCF was estimated as 0.24. Using the BCFs, the MCsoil was determined as 0.8 mg/kg to avoid exceeding the MRL (0.2 mg/kg) for scallions. Continuous monitoring and management of residual fluopyram in soil is necessary to

ensure compliance with MRLs, since this fungicide has the potential to persist for extended periods of time.

**Author Contributions:** Conceptualization, M.-S.Y. and H.C.; methodology, M.-S.Y. and H.C.; software, H.C.; validation, M.-S.Y. and H.C.; formal analysis, M.-S.Y.; investigation, M.-S.Y. and H.C.; resources, H.C.; data curation, H.C.; writing—original draft preparation, M.-S.Y. and H.C.; writing—review and editing, M.-S.Y. and H.C.; visualization, M.-S.Y. and H.C.; supervision, H.C.; project administration, H.C.; funding acquisition, H.C. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Rural Development Administration, grant number PJ01527705.

**Data Availability Statement:** All related data and methods are presented in this article.

**Conflicts of Interest:** The author Yun, M-S. is currently employed by the company Hanearl Science Ltd. However, this study was not financially supported by the company. Therefore, there is no conflict of interest between the company and this research.
