Behavior of sprayed tricyclazole in rice paddy lysimeters

Thai Khanh Phong, Dang Thi Tuyet Nhung, Kenichi Yamazaki, Kazuhiro Takagi, Hirozumi Watanabe, Thai Khanh Phong, Dang Thi Tuyet Nhung, Kenichi Yamazaki, Kazuhiro Takagi, Hirozumi Watanabe

Index: Chemosphere 74(8) , 1085-9, (2009)

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Abstract

The behavior of sprayed tricyclazole in rice paddy lysimeters was studied. Tricyclazole residues were measured from rice leaves and paddy water after tricyclazole spraying in paddy lysimeters. The rate of photolysis and hydrolysis of tricyclazole on the surface of rice leaves was also determined in a laboratory experiment. Tricyclazole was extracted from leaf and water samples and determined by liquid chromatography with UV or mass spectrometry. The hydrolysis half-lives of tricyclazole on rice leaves were 11.9 and 5.1 d for the formulated product and standard, respectively. The photolysis half-lives were longer, 16.4 d for the formulated product and 20.9 d for the standard. In the paddy lysimeter, tricyclazole dissipation on leaves involved either biphasic first-order kinetics or single-phase first-order kinetics, depending on the rainfall pattern. Half-lives of tricyclazole on lysimeter rice leaves were from 3.0 to 5.7 d. The dissipation of tricyclazole in paddy water followed single-phase first-order kinetics with half-lives ranging from 2.1 to 5.0 d.