Aerobic degradation under non-sterile laboratory conditions led to fluopicolide degrading to a minimum of 53%AR after 120 days (53%AR after 120 days was recorded, however, AR recovery was only 77% at this timepoint). Degradation of the pyridinyl ring led to the formation of the metabolite M-02 (max 7% AR) plus additional unknown metabolites A, B, C and D (max 4% AR up to 120 days); the benzoyl ring degraded to metabolites M-01 (max 25% AR at end of study up to 200 days), M-03 (max 11% AR) and other minor unidentified metabolites (max 0.2%). There is some evidence that M-03 reaches its highest levels in acid soils, probably as a result of slower degradation of M-03 in such soils. CO2 and other volatiles were found at a maximum of 2.5% over the study period. Degradation of fluopicolide under sterile conditions was increased compared to non-sterile conditions indicating that microbial activity does not necessarily enhance fluopicolide degradation rates; the reasons for this potentially enhanced degradation under sterile conditions are not known. The metabolites M-01 and M-02 accumulated under sterile conditions, but were degraded under non-sterile conditions, indicating that they would be susceptible to microbial degradation. Unextracted residues of fluopicolide at 100 days ranged between 10 - 12% in the pyridinyl labelled ring and between 2 - 7% in the benzoyl labelled ring. The general trend was for the level of unextracted residues to increase slowly as the studies progressed. An aerobic study was also conducted at 10°C; under colder conditions fluopicolide was degraded more slowly, resulting in a mean DT50 of 901 days (RMS calculation). No differences in route of degradation at lower temperature were detected. The Applicant proposes that the primary metabolic pathway in soil involves the degradation of fluopicolide initially by hydroxylation of the aliphatic bridge between the two aromatic ring moieties to form the hydroxylated metabolite M-03. This step probably occurs in all soils, and occurs slowly. Cleavage of M-03 is then pH dependent, and M-03 probably only exists transiently in neutral and alkaline soils. M- 03 cleaves to form the metabolites M-02 containing the pyridine ring and M-01 containing the phenyl ring. M-01 then slowly degrades leading to the formation of carbon dioxide and soil bound residues and other very minor metabolites. Metabolism of M-02 proceeded via a number of pathways with the initial steps hydroxylation of the pyridinyl ring to form the metabolite M-13 and a postulated reaction with glutathione to form a transient intermediate that can be oxidised to M-10, oxidised and hydroxylated to M-11 and M-12, or methylated and oxidised to M-05. M-10 may then be hydroxylated to M-11 and M-12 and M-05 to M-14 respectively.