Leaching behaviour of azoxystrobin andmetabolites in soil columns

Abstract

BACKGROUND:Azoxystrobin[methyl(E) - 2 - {2 - [6 - (2 - cyanophenoxy)pyrimidin - 4 - yloxy]phenyl} - 3 - methoxyacrylate],astrobilurin fungicide, is a broad - spectrum, systemic and soil - applied fungicide. Azoxystrobin has been registered for rice cultivation in India, but no information is available on its leaching behaviour in Indian soils. Therefore, leaching behaviour of azoxystrobin was studied in packed and intact soil columns under different irrigation regimes. RESULTS: Azoxystrobin did not leach out of the 300mm long columns after 126 and 362mm rainfall. After percolating water equivalent to 362mmrainfall, azoxystrobin leached downto 10–15 cm(packed columns) and 15–20 cm(intact columns) depth. Azoxystrobin was not detected in the leachate from the packed column leachedwith 94.5mLwater everyweek (140mmrainfall per month) during the 28 weeks of the study period. However, azoxystrobin acid, formed by azoxystrobin degradation, was detected in the leachate after 18 weeks. At the end of the study, azoxystrobin had leached down to 5–10 cm depth, and only 60% of initially applied azoxystrobin was recovered from the soil. CONCLUSION: The results indicate that azoxystrobin is fairly immobile in sandy loam soil, but azoxystrobin acid, a major metabolite of azoxystrobin, is quitemobile andmay pose a threat of soil and groundwater contamination.