Influence of Phytosanitary Practices in Tunisian Vineyards on the Presence of Pesticide Residues in Winegrapes

Background and goals No research or monitoring plans on winegrapes have yet been established regarding Tunisia’s pesticide residues. Therefore, the correlation between Tunisian grapegrowing phytosanitary practices and pesticide residue presence in winegrapes was evaluated. Comparisons were made with Tunisian legislation regarding the use of active substances and with European Union legislation and Codex Alimentarius regarding pesticide residues.

Methods and key findings A survey was conducted in northeastern Tunisia. During two growing seasons (2018 to 2019 and 2019 to 2020), the phytosanitary practices of ~40 grapegrowers were investigated. Simultaneously, 53 and 55 winegrape samples were collected and analyzed for pesticide residues by liquid and gas chromatography coupled with tandem mass spectrometry. According to the survey, grapegrowers respected preharvest intervals, but some deviations from Tunisian legislation were observed in commercial product selection and dosage recommendations. Less than 15% of the applications of active substances in the vineyards led to the detection of residues in winegrape samples. Approximately 40% of the detected residues came from active substances not reported by the surveyed grapegrowers. Drift from neighboring fields and degradation products of approved substances could explain at least half of these unexpected findings. European Union legislation maximum residue levels were exceeded in 36 samples, while Codex Alimentarius maximum residue levels were exceeded in three samples.

Conclusions and significance It is recommended that Tunisian authorities implement a monitoring program to ensure the correct use of phytosanitary products in the vineyards, and provide training for grapegrowers regarding good agricultural practices.