Polyurea microcapsule encapsulation improves the contact toxicity, inhibition time and control effect of trans-2-hexenal against Fusarium graminearum

Trans-2-hexenal (T2H) shows satisfactory antagonistic activity against Fusarium graminearum, but its strong volatility and poor water solubility limit its further application in Fusarium head blight (FHB) control. In this study, T2H-loaded polyurea microcapsules (PU MCs) with different particle sizes were successfully prepared by an interfacial polymerization method, and the effect of MC encapsulation on the physical property limitations and bioactivity of T2H was evaluated. After being encapsulated, lipophilic T2H could be stably dispersed in water. MC encapsulation reduced the fumigation toxicity of T2H but increased its contact toxicity. The smaller the particle size was, the higher the toxicity of PU MCs to F. graminearum was. After 6 d of application, the inhibition rate of T2H against F. graminearum decreased by 77.26%, while that of T2H-loaded PU MCs with small particle sizes (T2H-loaded PU MCs-S) decreased by 54.29%, indicating that MC encapsulation prolonged the inhibition time of T2H. The results of the inoculation assay showed that MC encapsulation improved the inhibitory effect of T2H on F. graminearum infection and DON production in stored wheat kernels. Furthermore, seed soaking with T2H-loaded PU MCs-S reduced the pathogenic fungal load of wheat seeds and had no significant effect on seed germination. In conclusion, T2H encapsulated in MCs can be developed as a plant protection product for postharvest and presowing treatment of wheat.