Potential control of tropical phytopathogenic fungi using CaZn2(OH)6·2H2O, ZnO, and Ca(OH)2 nanoparticles.

Phytopathogenic fungi are a major threat in tropical agriculture, causing diseases in crops and postharvest fruits that lead to significant economic losses. Although synthetic fungicides are commonly used for their control, their environmental persistence and toxicity have raised the need for safer alternatives. In this study, the antifungal potential of CaZn2(OH)6•2H2O] (CZ), ZnO, and Ca(OH)2 nanoparticles (NPs) synthesized por sol-gel (SG), hydrothermal (HT), microwave-assisted (MW), and mechanochemical (MC) methods was evaluated. A total of 53 fungal strains were isolated from symptomatic plant material, and their pathogenicity was confirmed in 10 strains, primarily from Colletotrichum and Fusarium, using Koch's postulates. Susceptibility to conventional fungicides (mancozeb, prochloraz, and benomyl) and antifungal activity of NPs were assessed through microdilution and poisoned plate assays. All NPs exhibited fungicidal effects, with minimum fungicidal concentrations (MFCs) ranging from 0.039 to 5.0 mg·mL- 1. In poisoned plate assays, SG-derived NPs showed the highest inhibition rates (0.2%-100%) and induced macro- and micromorphological alterations, including the paradoxical effect. CZ NPs were particularly effective in inhibiting conidia germination, while ZnO NPs mainly targeted hyphal growth. The in vitro efficacy of these NPs supports their potential use in integrated disease management programs. Further validation under field conditions and ecotoxicological studies will help consolidate their role in sustainable crop protection.