Degradation and Adsorption of a Seed Fungicide Pefurazoate in Paddy Soil

Abstract

Fate of the fungicide, pefurazoate (pent-4-enyl N-furfuryl-N-imidazol-1-ylcarbonyl-DL-homoalaninate, Healthied^®) in flooded mineral and volcanic ash soils was investigated with ¹⁴C-labeled pefurazoate. ¹⁴C-Pefurazoate, when applied at 1ppm, was quite easily degraded with a half-life of less than one week in both soils. Pent-4-enyl N-furfuryl-DL-homoalaninate, N-furfuryl-DL-homoalaninate, 1-[(RS)-1-carboxylato-propyl]-3-hydroxypyridinium, and N-(furan-2-ylcarbonyl)glycine were identified as major degradation products, amounting to less than 10% of the applied radioactivity. The radioactivity in the soil decreased due to the evolution of ¹⁴CO₂, which was an ultimate metabolite of pefurazoate. The Freundlich adsorption coefficient of pefurazoate was 16.3 in the mineral soil and 21.9 in the volcanic ash soil, suggesting pefurazoate was not adsorbed tightly by the soils.