Hebei Messi Biology Co., Ltd. stated that leaf spot is an important leaf disease of mango, which causes the decline of mango yield and quality. Nano-magnesium hydroxide is easy to prepare, environmentally friendly and has a wide antibacterial spectrum, and is widely used in the field of antibacterial. The pathogenic fungi of mango leaf spot were isolated and purified. Through morphological observation and ITS-rDNA sequence analysis, the isolated strain was determined to be the pathogen of mango Phomopsis leaf spot, belonging to the genus Diaporthe musigena.
Three nano-magnesium hydroxides with different morphologies were synthesized and prepared, named MHNPs-MgO600, MHNPs-MgO80 and MHNPs-MgCl. The sizes of the three nanoparticles on the (101) plane were calculated by X-ray powder diffraction (XRD) and Scherrer formula, which were 60.50, 11.63 and 13.52 nm, respectively. The three kinds of nano magnesium hydroxide were characterized by scanning electron microscopy, specific surface area analyzer and Zeta potential analyzer. They were regular flakes, petals and hexagons, respectively, and there were great differences in specific surface area, surface charge and other characteristics.
The inhibition rate of nano magnesium hydroxide on pathogens was calculated by flat plate coating method. It was found that the three kinds of nano magnesium hydroxide could effectively inhibit the growth of mango leaf spot pathogens. MHNPs-MgO80 with the largest specific surface area and the smallest Zeta potential had the best inhibition effect, and the inhibition effect was more obvious with the increase of magnesium hydroxide mass concentration. The inhibition of different nano magnesium hydroxides on mango leaf spot pathogens was compared, and it was found that specific surface area and Zeta potential were the main factors affecting the antibacterial effect. The research results provide relevant scientific basis and technical support for the selection of efficient and environmentally friendly nano magnesium hydroxide antifungal preparations.