Abstract
This study examined the antifungal activity of cold aqueous extracts from ten locally available plant species in Libya against Fusarium oxysporum f. sp. lycopersici, the causal agent of tomato wilt disease. The pathogen was isolated from infected tomato plants collected in the Ain Zara region and identified through cultural and microscopic characteristics, with confirmation using Komada selective medium. Plant materials were extracted by cold maceration, and the resulting solutions were tested using the poisoned food technique at concentrations of 20, 40, 60, 80, and 100%. Clear differences were recorded among the plant extracts in their ability to inhibit fungal growth. Clove extract was the most effective, achieving complete inhibition at concentrations of 40% and above. Garlic, thyme, and pomegranate peel also showed strong antifungal activity, with garlic producing full inhibition at 80–100% and thyme at concentrations of 60% and higher. In contrast, extracts of wormwood (Artemisia herba-alba) and oleander (Nerium oleander) caused minimal inhibition even at maximum concentration. Microscopic observations revealed that the most active extracts significantly reduced the formation of macroconidia and microconidia after 14 days, while chlamydospores remained less affected. Preliminary phytochemical screening indicated that the highly active extracts contained phenolics, flavonoids, terpenoids, tannins, and alkaloids, compounds known to disrupt fungal structures and interfere with essential metabolic processes. These findings demonstrate that aqueous plant extracts—particularly clove, garlic, thyme, and pomegranate—offer promising, environmentally friendly alternatives to synthetic fungicides. Further greenhouse and field studies are recommended to evaluate their applicability within sustainable disease management programs for tomato production in Libya.