| Compared with common pesticide formulations,microcapsules have many advantages such as prolong controlling effect, improve using efficiency, avoid decomposition and invalidation, abate toxicity and harmfulness, reduce environment pollution, and so on. At present, researches on pesticide microcapsules in China are mainly fasten on screening the recipe, optimizing the process conditions of preparation, and characterizing the release, etc. There were few reports about that release behavior of pesticide microcapsules, encapsulated by the different wall material, in the condition of pesticide application. Using polyurethane (PU) and urea-formaldehyde (UF) as the wall material, the phoxim microcapsules (MC) were prepared by the interfacial polycondensation and in-situ polymerization respectively. After spraying with the dilutions of tested preparations on the cabbage leaf, the leaves were picked and fed the 4th-instar larvae of black cutworm in different days; the mortalities of larvae represented the release rates of microcapsules. For the same purpose, the safety on cucumber was also conducted. Using polyurethane (PU) and urea-formaldehyde (UF) as the wall material, the acetochlor microcapsules (MC) were prepared by the two above methods. After mixing with the herbicides of tested preparations in the soil, the soil, containing herbicides, were picked and culturing the fungus in different days, the inhibitory rate of growth of fungus represented the release rates of microcapsules. Using soil column to study the leaching of herbicides. The main contents is as the following aspects:1. Encapsulated the phoxim and acetochlor were prepared by in-situ polymerization. It was found that the optimal conditions were the optimal F/U mole ratios 1.75, curing temperature 60℃, dispersing agent 2%Sodium Ligninsulfonate,the amount of the wall 3~3.5%(wt/wt). The result of performance was the encapsulation efficiency over 90%, the drug loading rate over 80%. The UF microcapsule showed excellent surface morphology and the product displayed high encapsulation efficiencies. The microcapsule capsule-shaped spherical, and the wall material is a slight convexity non-porousfilm.2. Encapsule of phoxim and acetochlor were prepared by interfacial polycondensation. It was found that the optimal conditions were MDI:PEG=1:0.5, ratio of core to wall 10:1, emulsifier EL-40, curing temperature 50℃for 3h. The result of performance was the encapsulation efficiency over 90%, the drug loading rate over 80%. The microcapsule capsule-shaped hemispherical, and the wall material is smooth non-porousfilm.3. Release kinetics study shows that The Release of two species of microcapsule could be described by the first order kinetics equation.4. Results indicated that the persistent period of urea-formaldehyde microcapsules was the longest, in all the experiments preparations, which was 10 days longer than that of EC. The persistent period of polyurethane encapsulation was 3-5 days more than EC. To the susceptible crop of cucumber, urea-formaldehyde microcapsule of phoxim showed the maximum security, the polyurethane microcapsules followed, and the most serious injury was caused by EC.5. The study of durable effect in soil showed that the period of EC was longer than urea-formaldehyde microcapsule, and short than polyurethane microcapsule. The determination of herbicide in soil showed that the residues in soil of two species of microcapsule were similar, but they were obviously higher than that of EC. To the leaching of herbicide, urea-formaldehyde microcapsule showed the weakest mobility, the polyurethane microcapsules followed, and the maximum mobility was caused by EC.6. After 75 days, in corn field of , the control effect of EC have lower than 50%, but the microcapsules's higher than 80%, still. After 180 days, in garlic field, the control effect of EC was lower than 40%, but the microcapsules were higher than 80%. The persistent period of microcapsules was longer than EC, but it was not discriminative between microcapsules which encapsulated by different wall.
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