Disappearance of pyrimethanil residues on tomato plants.

The objective of this work was to estimate the disappearance of pyrimethanil, the active ingredient of Mythos 300 SC, at present, commonly used for the protection of greenhouse vegetables against diseases of fungal origin. Disappearance trends of the chemical deposits were studied on tomato plants grown in commercial greenhouses sprayed with a homogeneous 0.15% aqueous solution of the plant protection product. It was found that, on average, pyrimethanil residues on ripening fruits dropped by half and reached detection limit level in 5.7 and 13.7 days after Mythos 300 SC application, respectively. Pyrimethanil residues on tomato leaves dropped by half within 4.0 days and reached detection limit level in the first 10.5 days. Therefore, in conditions of high infection pressure, there is a need to repeat the fungicide application as early as after 3 or 4 days after previous application of Mythos 300 SC.