Fluopyram-trifloxystrobin residues in cucumber drop below quantification within 10-15 days
A field study found that residues from a fluopyram-trifloxystrobin premix in cucumber fell below the 0.01 mg/kg quantification limit within 10 to 15 days after the final spray, while calculated dietary risk remained negligible under good agricultural practice.
A field study published in Scientific Reports assessed residue dissipation and dietary risk for a premix of fluopyram 250 + trifloxystrobin 250 g/L SC in cucumber. Researchers measured residue dynamics after three foliar applications at the recommended rate of 600 mL/ha and at 1.25x, or 750 mL/ha. Initial residues ranged from 0.412 to 0.555 mg/kg for fluopyram, 0.348 to 0.561 mg/kg for trifloxystrobin, and 0.158 to 0.218 mg/kg for the metabolite CGA321113.
All three compounds followed first-order dissipation kinetics. Half-lives were 2.25-2.69 days for fluopyram, 1.19-2.01 days for trifloxystrobin, and 1.14-2.11 days for CGA321113. The study reported that residues declined below the quantification limit of 0.01 mg/kg within 10-15 days after the final spray. Analytical validation used a QuEChERS method followed by gas chromatography and GC-MS/MS, with recoveries between 80% and 103%, relative standard deviation below 10%, and linearity above R² 0.998.
For crop protection practice, the main significance is the link between residue behaviour and food safety assessment. Hazard quotient values for both rural and urban consumers remained below one, which the authors interpreted as negligible chronic and acute dietary risk when the product is used according to good agricultural practice. For vegetable growers, that reinforces the importance of respecting dose rates and pre-harvest intervals if they want residue compliance and market access when using premix fungicides on fast-turnover crops such as cucumber.