Cross-Enhanced Degradation of Dicarboximide Fungicide Residues in Soils

Abstract

The dicarboximide fungicides iprodione, procymidone, and vinclozolin are widely used to control <i>Botrytis</i> bunch rot on grapes. The degradation rates of these chemicals in five vineyard soil samples in the Penedès region (Catalonia, Spain) had been previously determined. These soil samples had been treated with the fungicide iprodione, procymidone, or vinclozolin three times under laboratory conditions over 200 days. The objective of this study was to evaluate the cross-enhanced degradation of these fungicides in soils from the previous study to determine if a soil sample previously treated with a dicarboximide fungicide enhanced its own degradation but not the degradation of the other compounds. The analyses were conducted over a 77-day period beginning on the same day of each cross-treatment. Under these conditions, for each fungicide, the time to 90% degradation was ~7days if the soil was pretreated with the same fungicide and was 35 to 56 days if the soil was pretreated with one of the other fungicides, indicating that cross-enhancement of degradation did not occur. This study demonstrated a clear trend toward higher rates of fungicide loss in soils with three applications of the same fungicide.