# Green Synthesis, Characterization, and Antifungal Efficiency of Biogenic Iron Oxide Nanoparticles
## 1 Introduction  
Fungi have been identified as the primary cause of significant reductions in crop yields across a wide range of agricultural produce. In developing countries, the situation is exacerbated, with fungal damage contributing to approximately 20-25% of overall production [1]. In contemporary times, the extent of fruit losses attributed to phytopathogenic fungi has been approximated to surpass 50% of the total agricultural fruit production [2]. Fungi are currently being recognized as emerging hazards to the health of animals, plants, and ecosystems [3]. Furthermore, the presence of fungal growth on food items can lead to the development of mycotoxicosis, a condition that arises from the consumption of mycotoxins. This can result in various severe manifestations, including acute poisoning, cancer, and liver diseases [4]. The occurrence of significant food waste has been attributed to the decomposition of fruits caused by fungal infections. Harvested fruits are susceptible to fungal attack due to factors such as abundant moisture, acidic pH, increased nutrient availability, and reduced intrinsic resistance [5]. Taking into account the reduction in crop productivity, _Alternaria_ is identified as one of the most destructive saprophytic and pathogenic genera that impact matured and harvested vegetables and fruits [6]. Among the various species within this genus, _Alternaria alternata_ has garnered significant attention in the academic literature due to its extensive documentation. Notably, this species has been found to possessthe capability of producing over 30 distinct mycotoxins [7]. _A. alternata_ is responsible for inducing black spot rot on apple fruit and has the potential to generate various detrimental metabolites during its invasion [8]. Moreover, _A. Alternata_ is known to produce non-host specific toxins, including alterna!i monomethyl! ether, alterna!iol, and tenuazonic acid, during its mycological growth. These toxins have the potential to posture a hazard to human health [9]. Furthermore, _A. Alternata_ has been documented as a causative agent for several diseases, including citrus canker [10], core apple rot [11], Alternaria rot in nettled melon [12], and dragon fruit black rot [13]. In this context, _A. Alternata_ fungus establishes its initial infection in the fruit via the peel or styles, typically through the growing period. Subsequently, it stays in a dormant condition until the fruit attains full maturity [14]. Various methodologies have been employed to manage the presence of _A. Alternata_ in tomato crops [15]. Currently, the management of diseases relies on the application of agrochemicals, such as fungicides. Despite the numerous advantageous qualities of fungicides, such as their high availability, reliability, and fast action, it is important to acknowledge that these substances can have detrimental effects on non-target organisms [16]. The primary reason for their harmful effects is attributed to their toxic properties and their systemic mechanism of action, which interferes with the levels of metabolites in the biosynthesis pathway of aromatic amino acids in soil microorganisms. Moreover, it should be noted that these fungicides possess non-biodegradable properties, leading to their accumulation in water, soil, and plants. This accumulation subsequently results in detrimental consequences for other organisms within the ecosystem [17]. Additionally, the overuse of chemical fungicides can contribute to the development of fungal resistance, which in turn leads to a harmful impact on the environment [18]. Furthermore, it has been evaluated that approximately 80-90% of fungicides that are sprayed are subsequently lost to the environment either during or after their application [19]. Therefore, it is imperative to acquire fungicides that exhibit superior performance while remaining economically viable and minimizing adverse environmental effects.