Green Pesticide High Activity Based on TiO₂ Nanosuspension Incorporated Silver Microspheres Against Phytophthora palmivora

Cocoa pod production has experienced a significant decline due to attacks by the Phytophthora palmivora (P. palmivora) fungus, which is the main cause of cocoa pod rot. To overcome this problem, Titanium dioxide (TiO₂) was chosen because of its potential as an antifungal, and its activity can be increased by adding silver nanoparticles (AgNPs). This research aims to determine the antifungal properties of TiO₂–Ag nanosuspension on the growth of P. palmivora under exposure to UV, Visible and without irradiation. The sol–gel process was used to synthesize TiO₂, and ultrasonics was used to integrate silver nanoparticles into TiO₂. Characterization of UV–Vis diffuse reflectance spectroscopy (UV-DRS) shows a change in the energy gap from 3.24 to 2.82 eV. The Fourier confirmed the crystal structure of the TiO₂-Ag anatase transform infrared spectroscopy (FTIR) spectrum, which showed the stretching vibration peak of the Ti–O and Ag–O bonds (463.88 cm⁻¹). Particle size analysis (PSA) characterization revealed that the nanoscale of TiO₂–Ag was 92.4 nm. The disc diffusion method was used to test the antifungal inhibitory of 0.1%, 0.3%, and 0.5% TiO₂–Ag against P. palmivora. The antifungal activity of the TiO₂–Ag showed strong resistance under exposure to visible light, and the optimum concentration of TiO₂–Ag was 0.5%.