Dissipation kinetics of tebuconazole on Malus domestica (Golden Delicious and Jonathan) in an apple orchard from north-eastern Romania

Abstract

Tebuconazole (TEB) dissipation behavior on Golden Delicious and Jonathan leaf, bark, peel and flesh apple samples was investigated in the present work. The interest fungicides were sequentially applied as a spray in four foliar applications, in full agreement with an apple orchard-protection program recommended by Bayer. For studying TEB dissipation, apple tree related samples were collected in advance (reference) and as soon as applications dried out (3 h), and then at 2, 5, 7.5, 10, and 15 day after the treatment. Reference apple tree samples were analyzed by gas chromatography tandem mass spectrometry for their corresponding chemical and phytochemical composition. Tebuconazole dissipation on apple leaf, bark and peel could be adequately described by a single first-order kinetic model. In apple flesh samples traces of TEB were not detected. Higher TEB dissipation rate constant was observed in apple leaf than in peel and bark apple samples. The half-life time of TEB varies in the 2.71–16.03 d range and might reach a critical value of 1 d under the most reactive circumstances. The results obtained in the present study show that the dissipation parameters are sensitive to the composition of used combined fungicide formulations and also to their corresponding applied dose.