Mohamad Firdaus Ahmad

Palm oil is a major agricultural commodity and an important economic driver in Asia. However, the sustainability and productivity of this crop are constantly threatened by a range of pathogenic fungi, especially Ganoderma boninense. Therefore, this study aimed to develop an eco-friendly hexaconazole-loaded nanoemulsion (Hexa-NE) for effective and targeted fungicide delivery while reducing environmental and health impacts. The optimized Hexa-NE formulation was evaluated for particle size, polydispersity index (PDI), zeta potential, pH, viscosity, and morphology using Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). Fungicide release, stability, and antifungal activity were conducted to assess the overall efficacy and performance of the formulation. The Hexa-NE exhibited particle size of 105.8 nm, a PDI of 0.358, a zeta potential of −53.53 mV. The formulation remained stable over three months of storage. It also demonstrated favourable physicochemical properties including low viscosity (30.24 mPa·s), low surface tension (23.87 mN/m), and suitable pH (6.14) for foliar application. TEM and SEM analyses confirmed spherical droplets and revealed significant hyphal damage to G. boninense. The antifungal test showed a higher inhibition of 97.1% at 0.1 µM of Hexa-NE as compared to hexaconazole solution which only 40% at the same concentration. Release studies exhibited a sustained release of hexaconazole, which may prolonged fungicidal activity. In conclusion, Hexa-NE showed promising laboratory-scale antifungal performance against G. boninense. These findings support its potential for further investigation as a nanoformulated fungicide for future greenhouse and field evaluations.

Agrichemical adjuvants that combine a highly selective, efficient, and active mode of operation are critically needed to realize a more sustainable approach to their usage. Herein, we report the synthesis and full characterization of two new metal-organic frameworks (MOFs), termed UPMOF-1 and UPMOF-2, that were constructed from eco-friendly Ca2+ ions and naturally-occurring, low molecular weight plant acids, L-malic and D-tartaric acid, respectively. Upon structural elucidation of both MOFs, a widely-used fungicide, hexaconazole (Hex), was loaded on the structures reaching binding affinities of -5.0 and -3.5 kcal mol-1 and loading capacities of 63 and 62% for Hex@UPMOF-1 and Hex@UPMOF-2, respectively, as a result of the formation of stable host-guest interactions. Given the MOFs’ framework chemistry and predisposition to disassembly in relevant agricultural conditions, the sustained release kinetics were determined to show near quantitative release (98 and 95% for Hex@UPMOF-1 and Hex@UPMOF-2, respectively) after >500 h – a release profile drastical-ly different than the control (>80% release in 24 h), from which the high efficiency of these new systems was established. To confirm their high selectivity and activity, in vitro and in vivo studies were performed to illustrate the abilities of Hex@UPMOF-1 and Hex@UPMOF-2 to combat the known, aggressive pathogen Ganoderma boninense (G. boninense) that causes basal stem rot disease in oil palm. Accordingly, at an extremely low concentration of 0.05 μg mL-1, both Hex@UPMOF-1 and Hex@UPMOF-2 were demonstrated to completely inhibit (100%) G. boninense growth and during a 26-week in vivo nursery trial, the progression of basal stem rot infection was not only completely halted upon treatment with Hex@UPMOF-1 and Hex@UPMOF-2, but seedling growth accelerated given the additional nutrients supplied via the disassembly of the MOFs. This study represents a significant step forward in designing adjuvants to support the environ-mentally responsible use of agrichemical crop protection.