Effect of <i>Leucaena leucocephala</i> extract in inhibiting mycotoxins produced by the fungus <i>Fusarium solani </i>isolated<i> </i>from Al-Rashidiya/Mosul city

Fusarium solani is a significant plant pathogen causing wilt and root rot in Solanum lycopersicum, leading to substantial yield losses. It also produces dangerous mycotoxins. Therefore, there is a pressing need for safe and natural alternatives to control its growth and toxin production. The objectives of this study were to isolate and identify F. solani from infected tomato plants and to evaluate the efficacy of an alcoholic extract of Leucaena leucocephala leaves in inhibiting its growth and reducing mycotoxin production. The fungus was isolated from The soil surrounding the roots of tomato plants and part of the roots from Al-Rashidiya/Mosul city and identified based on its morphological characteristics, its whitish-gray color, and the presence of microspores, macrospores, and chlamydospores. Various concentrations (up to 15%) of the alcoholic extract were used in liquid growth media, and dry weight of fungus was measured after 15 days. Mycotoxins were also determined using HPLC based on standard retention times. The results showed that the extract led to a gradual decrease in the dry weight of the fungus, with the lowest weight recorded at a concentration of 15% (5.0 g). HPLC revealed the presence of fumonisin, zearalenone, and fusaric acid at retention times of 3.08, 4.98, and 6.50 minutes, respectively. Toxin concentrations decreased with increasing extract concentration; fumonisin reached 14.5 mg/L and fusaric acid 19.20 mg/L at 15%, while zearalenone disappeared at concentrations of 10% and 15%. These results confirm the potential use of leucine extract as a safe and natural antifungal agent to inhibit the growth and reduce toxicity of F. solani thus promoting application of biological control in agricultural products.