Persistence of oxyfluorfen in soil and detection of its residues in rice crop

Oxyfluorfen is a post-emergence herbicide used for control of annual and perennial broad-leaf weeds and sedges in rice. There is increasing concern about persistence of pesticide residues in soils, agricultural products and sub- sequent contamination of ground water through runoff, leaching and drift. Thus, persistence of oxyfluorfen was evaluated under field conditions in a rice cropping system. Oxyfluorfen was sprayed at 240 and 500g aiha -1 application rates to the rice crop as post-emergence herbicide. Paddy grains, straw and soil samples were collected at harvest and analyzed for oxyfluorfen residues by HPLC. Straw samples contained 0.01 and 0.03μgg -1 oxyfluorfen residues at 240 and 500g ha -1 concentrations, respectively. In the soil, 0.028 and 0.03 mg g -1 of oxyfluorfen residues were detected when applied at 240 and 500 g ai ha -1, respectively. However, in rice grains, 0.018 and 0.106 μg g -1 of oxyfluorfen residues were found in 240 and 500 g ai ha -1 treated plots. In light of the potential adverse effects of oxyfluorfen, it is important to determine herbicide levels in these crops. © 2009 Taylor & Francis.