| Rice growth was infected by many kinds of diseases, insects and weeds in paddy field. Conventional high volume spray method wasted time and labor, but had low working efficiency. Labour-saving application method was develpoed though preparation and application of Spreading oil formulation(SO).Spreading oil was directly dropped on paddy water surface without spray procedure. The active ingredient dropped on paddy water surface, then to the whole water surface of the paddy field in a few minutes. The layer of the active ingredient maintains on the water surface and some parts of it are adsorbed into rice sheaths, so that the insects contact to the active ingredient on the water surface and rice plants die.Organic solvents are used in existing liquid pesticide formulations, such as dimethylbenzen, DMF and tetrachloromethane, which were human skin irritant and have higher toxic. These kinds of organic solvents could pollute the environment and cause healthy risk on human beings and animals after it releasing into the environment. Most biological organic solvents with non-toxic, non-polluting are biological esters, distilled from plants and animals or obtained by the synthetic. Bio-organic solvents are used in this formulation, and this spreading oil could efficiently control the rice planthoppers. Ethofenprox is a kind of ether pyrethroid with no structure of ester in its molecule. With the phenomena of planthopper having high resistance to imidacloprid, ethofenprox become an ideal pesticide which could substitute highly poisonous organophosphorus pesticides such as methamidophos and have broad market prospects .In this paper, the preparion of 5% ethofenprox SO, quality detection method, field efficacy and distribution on paddy field were studied. It aimed to provide technical support for in-depth study of this new formulation.1. Develop of 5% ethofenprox SOThe optimum formulation of 5% ethofenprox SO was developed by orthogonal experiment through the screening of the solvent and surfactant. The optimum solvent was 50.0% methyl laurate. The proportion of the mixture of surfactant, OP-4, OP-10, 2201 and film-forming additive , was 4:4:3:9(m/m), which was 10.0% weight of the formulation. The other component was carrier, which was 35.0% of the formulation.The spreading speed of 5% ethofenprox SO was 9.29cm/s and spreading area was 1882.74cm2. The formulation had been stored at room temperature, or (54±2℃) for 14-days without precipitate, crystallization or layer-separation. The decomposition rate was 0.06% and 0.10% by HPLC. Surface tension was 28.33mN/m and interfacial tension was 0.11mN/m at 35℃.2. Distribution of 5% ethofenprox SO in paddy fieldA new method was developed for measuring 5% ethofenprox SO residues on water surface. This method based on adsorption of oil-absorptive paper, by which samples adsorb in. Then the components of ethofenprox were determined by HPLC. The concentration of ethofenprox around rice was 402.19μg/mL, and the other part of water surface was 34.52μg/mL. The results showed that the concentration around rice is higher than the other part of water surface. This formulation improved contact and systemic insecticide effectiveness.3. Field Efficacy Experiment of 5% ethofenprox SOAfter using 5% ethofenprox SO, the formulation spreaded on paddy water surface. The field efficacy showed that the correction control effect was 52.09% at the third day and 78.51% at the seventh. Because the time of chemical application was in the time of wheat heading stage, the field efficacy was reduced. But the data showed that the harm of planthopper has been completely controlled.
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