Investigations on the metabolic fate of prochloraz in soil under field andlaboratory conditions

The degradation of prochloraz in different soils was investigated in field and laboratory experiments. In laboratory degradation experiments in the da rk, initial prochloraz concentrations decreased to 30-64% within 56 days, d epending on temperature and soil pH. In neutral to basic soils, formation o f up to 3.7% of the metabolite prochloraz-urea was observed. The rate of mi neralization was strongly pH-dependent, not exceeding 3.2% in the acidic an d 18.3% in the neutral to basic soils. Amounts of non-extractable residues ranged from 14 to 31%. Under field conditions, prochloraz disappeared much more rapidly with DT50 values of 11-43 days. The metabolites prochlorazform ylurea and prochloraz-urea were found in significant concentrations. Labora tory experiments with fresh and sterilized soils under UV irradiation confi rmed the enhancing effect of light on the formation of the primary metaboli te, prochloraz-formylurea. The latter is hydrolysed to prochlorazurea predo minantly by microbial degradation. (C) 1999 Society of Chemical Industry.