Traditional pesticide formulations show poor utilization and environmental safety due to their low foliage adhesion and large auxiliaries. In this study, a novel and environment-friendly indoxacarb formulation was prepared to improve the pesticide’s utilization rate, target control characteristics and ecological security. Indoxacarb-loaded waterborne polyurethane–sodium alginate (PU/SA) nanoemulsions with film forming properties, alkaline responsive release, high effectiveness against Spodoptera litura, and reduced acute contact toxicity for nontarget organisms were successfully prepared. The colloidal properties, swelling and release behaviors, leaf adhesion, degradation dynamics and bioactivity assay of the indoxacarb-loaded PU/SA nanoemulsions were determined. Results showed that the obtained indoxacarb-loaded microcapsule particulates were approximately 57 nm in diameter, electronegative −45.9 mV, and uniformly dispersed in the nanoemulsions. The dried latex films of PU/SA in the alkaline environment revealed better responsive swelling and release characteristics than those in acidic and neutral conditions. Compared with a commercial emulsifiable concentrate, the indoxacarb-loaded PU/SA nanoemulsions were useful for the targeted control of S. litura, which have alkaline gut and showed reduced acute contact toxicity to Harmonia axyridia. Furthermore, the PU/SA formulation had better foliage adhesion and indicated the property of controlled-release and a persistent effect.

Late blight is a potentially devastating disease of potato. Dimethomorph has been widely used for preventing and controlling this disease. However, there is little information on dimethomorph residue in potato and the production soil. To address this issue, the present study developed a method for accurate analysis of dimethomorph using high-performance liquid chromatography. A linearity that had a determination coefficient of 0.9998 was established based on dimethomorph concentrations from 0.05 to 10.0 mg/L. The recovery rates ranged from 76.61% to 109.11%. The limit of detection and the limit of quantification were 0.02 mg/kg and 0.05 mg/kg, respectively. Potato production experiments were then carried out in three provinces of China, and dimethomorph was applied through a foliar spray. The established method was used for analysing the uptake, dissipation, and residues of dimethomorph in potato leaves and tubers and also in soils. Results showed that foliar spray of dimethomorph was translocated to tubers and generally within 2 days. The half-lives of dimethomorph in potato leaves, tubers, and soil ranged from 2.65 to 4.20, 1.79 to 3.71, and 4.62 to 9.0 days, respectively. The risk assessment of dietary exposure showed that all of the risk index values and the hazard quotient were less than 100%, indicating that foliar spray of dimethomorph on potato at 1.5 times the recommended minimum dosages poses little risk for consumption of the tubers in the three provinces of China.