Abstract:

In order to reduce pesticide use in the Tiaoxi Watershed and lower environmental risk of the pesticides on aquatic organisms, a field survey was carried out of types and rates of the pesticides used to control leaf borers, planthoppers and rice sheath blight in the watershed; environmental risks of the pesticides assessed using the technique for pesticide risk assessment, and simulated shells for exposure of pesticides; and optimal types and optimal application rates of pesticides determined according to their risks, separately. Results show that the use of pymetrozine to replace buprofezin reduced the application rate of pesticide by 765 g·hm^-2; the use of avermectin to replace Jiaozi did by 0.75 L·hm^-2; and the use of Armure to replace Jinggangmycin did by 4.27 L·hm^-2. In total, the replacements of the conventional pesticides reduced the use of pesticides by 5.79 L·hm^-2. Meanwhile, the replacements improved crop yield and pest control effect in the experiment field over their respective ones in paddy fields of local farmers using conventional pesticide. Thanks to its lowered frequency and rates, the use of the replacement pesticides lowered pest control cost and in turn raised economic profit of the crop. Therefore, it could be concluded that this technology can reduce not only the total amount of pesticides to be used, but also their toxic impacts on aquatic bio-environment, thus controlling the non-point source chemical pollution at the source.

Key words: pesticide, non-point source pollution, control, Tiaoxi Watershed