Transformations of prothiocarb in plant and soil

Abstract

The behaviour of14C-labelled prothiocarb, N-(3-dimethylaminopropyl-(1-14C))-thiocarbamic acid-S-ethyl ester hydrochloride, was studied in two German standard soils and in tomato plants. Under the laboratory conditions used, the half-life of the fungicide was 59 days in the soil containing the higher percentage of organic matter and 144 days in the more acidic soil which was poorer in organic carbon. Besides14CO2, N, N-dimethyl propane-1, 3-diamine and diethyl disulphide, N-(3-methylaminopropyl)-thiocarbamic acid-S-ethyl ester (N-demethylprothiocarb) was tentatively identified as a major metabolite in both substrates. 1-Methyltetrahydro-1, 3-diazin-2-one and another unidentified, secondary product arising from chemical reactions (e.g. cyclization) of N-demethyl-prothiocarb were also found. In tomatoes, N, N-dimethylpropane-1, 3-diamine formed through hydrolysis of prothiocarb was the principal conversion product observed. As concluded from earlier results, the unchanged parent compound was the transport form in which the fungicide is being distributed within the plant organism. N,N-Dimethyl-propane-1,3-diamine, therefore, is proposed as target compound for total residue analysis.