Construction of lignin-based difenoconazole nanoparticles and control of bayberry twig blight disease

Twig blight disease has the characteristics of strong infectivity and rapid onset, which has brought great losses to the production of bayberry fruit. Lignin-based materials are widely used in the field of nanomedicine delivery due to their wide source, low price, and more active functional groups. In order to seek agents with slow-release function for better control of twig blight disease, Di@BLS nanoparticles were prepared by hydrophobically modifying sodium lignosulfonate (LS) and loading difenoconazole (hereafter referred to as Di) as a test agent, which was characterized by ¹H nuclear magnetic resonance (¹H NMR), fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), dynamic light scattering laser particle sizing (DLS), and the stability of the samples was analyzed by turbiscan stability analyzer (TSI); Di in leaves was extracted by QuEChERs method, and the uptake and translocation of Di@BLS in bayberry were investigated, and finally, diseased branches of bayberry collected for the isolation and identification of pathogenic fungi were carried out. The inhibitory effect of Di@BLS on the bayberry twig blight disease was investigated using the mycelial growth rate method and the pot experiment, respectively. The results showed that the average particle size of Di@BLS was 135.2 nm at a BLS carrier concentration of 1%, a feed/drug ratio of 5 : 1 and a SDS dosage of 0.2% by mass. The optimized formulation could maintain stability similar to that of Di ME while reducing the amount of surfactant. Both absorption transfer and field experiments confirmed that Di@BLS could delay drug degradation and persist longer in bayberry than Di ME. The results of the mycelial growth rate method showed that the EC₅₀ value of Di@BLS against Lasiodiplodia was 0.643 μg/mL, which is close to that of Di ME. In the pot experiment, at the mass concentration of 200 μg/mL, Di@BLS could reduce the incidence of blight of bayberry by 2.3% compared with Di ME. The results showed that the prepared nanoparticles Di@BLS had a long duration and good antifungal effect in bayberry, which provided a theoretical basis for the prevention and control of twig blight disease of bayberry.