Dissipation of 3 commercial formulations of penconazole 10% EC on greenhouse tomatoes in Lebanon
In Lebanon, same type of commercial formulations of an active ingredient from different manufacturers are registered and given the same critical Good Agricultural Practice (cGAP) as the reference formulation in spite of the fact that they differ in composition of co-formulants. The international guidelines require the performance of crop field trials for, at least, those active ingredients with claimed pre-harvest interval (PHI) of less than 7 days. Four comparative dissipation studies of 3 commercial formulations of penconazole 10% EC were performed on 4 varieties of greenhouse tomatoes under commercial field conditions along the coastal area of Lebanon. Two field replicate samples were taken at 5 different time intervals to assess the penconazole residue level. The analysis was conducted using gas chromatography tandem mass spectrometer GC/MSMS. Penconazole dissipation was described by 1st order kinetics with correlation coefficients ranging from 0.80 to 0.94 and a PHI of 1 day for penconazole is suggested. Data were statistically analysed to evaluate the dissipation behavior and the effects of field conditions among the 3 registered formulations. No statistically significant difference in the rate of dissipation among the three commercial formulations was revealed. It would be safer for food consumption to perform crop field trials under local conditions for formulations differing in co-formulants and claimed PHI of less than 7 days as per the guidelines.