Developing a natural fungicide from O/W Emulsion using essential oils and MgO nanoparticles

Abstract

For the farmers and cultivators to boost their crop yield in cultivation, preventing fungal attacks is an indispensable measure. In Sri Lanka as well as worldwide, vegetable and fruit cultivation and also ornamental plant cultivation are being extensively attacked by diseases like powdery mildew, downy mildew, grey mold, black spot disease, early blight disease, late blight diseases, etc., which are caused by fungal pathogens. Here in, a Pickering emulsion (PE) was formulated using trace amounts of magnesium oxide (MgO) nanoparticles (NPs) and cinnamon leaf (CL) oil as a natural fungicide. MgO NPs were synthesised by the sol-gel method using magnesium chloride (MgCl2) and sodium hydroxide (NaOH). The experimental yield of MgO NPs was achieved as 73.8%. The PE was formulated by mixing CL oil, deionised water and MgO NPs to get a homogeneous mixture. A polysorbate 80 emulsifier was used to enhance the stability of the emulsion. The most suitable emulsion system was comprised of 20% CL oil and 80% deionised water by mass percentage, and it was doped with 50 mg of MgO NPs to achieve a total mass of 50 g. To check the efficacy of the formulated PE, an antifungal susceptibility test was conducted against the fungus Aspergillus niger, a widely used model organism. Based on the inhibition zones, it was determined that the 1:10 dilution of the formulated PE exhibits the Minimum Inhibitory Concentration (MIC) required to inhibit the growth of the fungus Aspergillus niger, relative to the known positive standard, Fluconazole, at a concentration of 15,000 ppm. In the field, the diluted emulsion should be sprayed on the crops once every five days to get the best results. This method provides a natural and effective solution for managing fungal infections in cultivation, potentially leading to increased crop yields and healthier plants. A unique application for sustainable agriculture is offered by the combination of MgO NPs and CL oil in PE, which act as natural antifungal agents to lessen the need for synthetic fungicides. Future directions could investigate the feasibility of commercialising emulsion, particularly aimed at identified plant fungal pathogens, by integrating economically viable essential oils