Effects of fruit bagging on pesticide fate and fruit quality in peach under mixed-pesticide applications

Fruit bagging reduced initial pesticide deposits but slowed dissipation rates in peaches. • Fruit bagging altered spirotetramat metabolism, delaying the accumulation of spirotetramat-enol. • Terminal residues and dietary risks in bagging treatment remained within safe limits. • Peach bagging increased fruit size but reduced sugars, phenolics and flavonoids. Fruit bagging is widely adopted in peach production. However, its integrated effects on pesticide fate and fruit quality under mixed-pesticide applications remain insufficiently understood. This study systematically investigated the effects of peach fruit bagging on the deposition, dissipation kinetics, metabolism, dietary risk, and fruit quality of four commonly used pesticides (difenoconazole, azoxystrobin, thiacloprid, and spirotetramat) under greenhouse and open-field conditions. Our findings indicate that fruit bagging significantly reduced the initial deposits of all pesticides, but it also slowed dissipation, extending half-lives from 3.83 to 5.91 days in unbagged fruits to 4.15–6.67 days in bagged fruits, with black bags generally exerting a stronger effect than yellow bags. Bagging also modified spirotetramat metabolism by lowering and delaying the accumulation of spirotetramat-enol ( S -enol), indicating altered parent-to-metabolite conversion within the bagged microenvironment. Despite lower dissipation rates ( k ), terminal residues of all pesticides remained below the established safety limits before harvest, and both chronic and acute dietary exposures remained within acceptable ranges. In addition, bagging increased fruit weight but generally decreased soluble solids, total sugars, total phenolics, and total flavonoids, while increasing titratable acidity. Overall, fruit bagging acts as a microenvironmental control measure that simultaneously reduces direct residue loading, reshapes pesticide fate, and influences fruit quality. These findings provide new insights into the role of agronomic practices in controlling pesticide residues and support the optimization of bagging strategies for safe and high-quality peach production. Download: Download high-res image (240KB) Download: Download full-size image