Microbial degradation of chlorothalonil in agricultural soil: A laboratoryinvestigation

The employment of pesticides for crop protection must be balanced by a tota l awareness of the detrimental effects they may have on the environment. Pe sticide residues in soil, and metabolites resulting from microbial metaboli sm of such compounds, may contribute to pollution of streams, affect microb ial diversity, and influence essential symbiotic associations between micro organisms and crops. Chlorothalonil, an extensively used fungicide, is clas sified as a probable human carcinogen by the US EPA. Microbial degradation of chlorothalonil residues in different types of agricultural soil was inve stigated in the laboratory. Bacterial plate count and GC analysis results i ndicated that indigenous soil bacteria were able to utilize chlorothalonil, although the rate of chlorothalonil metabolism appeared to be influenced b y soil characteristics. (C) 2000 by John Wiley & Sons, Inc.