Dissipation of epoxiconazole in the paddy field under subtropical conditions of Taiwan

The environmental fate and distribution of fungicide epoxiconazole were stu died by a rice paddy field model ecosystem. One week before the head-sprout ing stage, rice plant was treated separately once with OPUS (tradename of e poxiconazole) 12% SC 2.1 kg ha(-1) and 1.4 kg ha(-1), respectively. Soil, w ater and rice plant were sampled seven days intervals nine times after appl ication. The bioconcentration factor of epoxiconazole on mosquito fish in t he ecosystem was also determined, based on the amounts of epoxiconazole con tent both in fish and water. This was initiated one day after the fungicide treatment, and continued for four days. In addition, the residue of epoxic onazole, in rice grains was analyzed after harvest. After harvest, both pla nted water spinach (Ipomoea aquatica Forsk) and edible amaranth (Amaranthus mangostanus L.) were analyzed. The results showed that epoxiconazole degra ded in the local environment under the experimental conditions described. T he degradation equations were in accordance with the first order kinetics. The DT50 of soil, field water and rice plant were 20-69 days, 11-20 days an d 14-39 days, respectively. The bioconcentration factors of epoxiconazole o n mosquito fish were 12.9 and 10.6 from 2.1 ka ha(-1) and 1.4 kg ha(-1) tre atment, respectively. Residues of epoxiconazole in both rice and harvest ve getables were non-detectable. This indicates that epoxiconazole applied to rice at the recommended rates and application frequencies will not accumula te on rice grain and successive cropping vegetables.