Abstract: [Objective] Carya cathayensis canker disease reduced the yield of pecan by 10%-50%, causing serious economic losses. The pathogen mainly infects the bark cells in the form of mycelium, multiplies through the spores and produce metabolites that have poisonous effects on the host cells, causing diseased spots in the trees and causing tree ulcer disease. In order to improve the control efficiency of C. cathayensis, we designed the reaction route, synthesized new bio-based materials were, and prepared micro-nano capsules that contained botryosphaeria dothidea fungicide, to obtain the new nano-bio-based pesticide release capsules with good release properties and antibacterial effects.[Method] Sodium alginate (SA), carboxymethyl cellulose (CMC) and carboxymethyl chitosan (CMCS) were used as raw materials to prepare new bio-based materials by esterification reaction with cholesterol by DCC and DMAP activation method, respectively. The molecular structure was characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (¹H NMR, ¹³C NMR), and X-ray diffraction (XRD). The new bio-based materials were used to prepare the micro-nano capsules by phase separation method to coat tebuconazole (Teb). The particle size of drug-loaded nanocapsules was measured by dynamic light scattering apparatus (DLS) and transmission electron microscopy (TEM). Encapsulation efficiency and slow release performance were measured by UV spectroscopy. Antibacterial effect was explored by using medium method and preliminary control experiment was conducted. [Result] The results showed that three novel nanobiosided tebuconazole microcapsules were successfully obtained. The particle size was 200-300 nm and the encapsulation rates were 72.5%, 69.7% and 71.1%, respectively. The cumulative release rates were 85.5%, 75.2% and 51.6%, respectively (the cumulative release rate of tebuconazole ethyl acetate, served as blank control, was 100%), and the release rate was in accordance with Peppas Kinetic equation. The good inhibitory rate of C. cathayensis canker disease was 32.4%, 28.8% and 23.8%, respectively (the tebuconazole ethyl acetate solution was 0%). Three kinds of drug loaded nanocapsules had good control effect for C. cathayensis canker disease of hickory, compared with the control effect of 98% tebuconazole. [Conclusion] The new nano-bio-based pesticide sustained-release capsules prepared in this study showed a good sustained-release effect, which was able to prolong the effective period of bacteriostat against C. cathayensis canker and achieve the purpose of improving the traditional control effect. The results not only provide a new technology for controlling the pathogen of C. cathayensis, but also provide new entrapment materials for anti-disease drugs.

Key words: Bio-based materials, nanocapsules, tebuconazole, sustained release, bacteriostatic, pathogen of carya cathayensis