Disposition of cyromazine in plants under environmental conditions

The disposition of cyromazine (Trigard) in plants under environmental conditions and the role of photodegradation in the formation of melamine were studied. Cyromazine was applied to three Brassica sp. vegetables, and residues were analyzed by high-pressure liquid chromatography. After multiple applications, both cyromazine and melamine were detected. Melamine residues constituted 14-36% of the total residues. After one application, the average half-life for cyromazine was 7 days. Melamine levels increased (3-5-fold) with time. Both compounds were readily removed by water. Percent residues removed decreased with increased elapsed time between application and washing. The role of photodegradation in the formation of melamine was studied by in vitro experiments. In glass dishes, cyromazine was dealkylated with the formation of melamine. Since the amount of melamine formed did not account for all of the lost cyromazine, volatilization of cyromazine and degradation to other metabolites is likely