Nano-Methanol Extract of Binahong (Anredera cordifolia) Leaves Inhibits Fusarium oxysporum Growth in vitro and Controls Fusarium Wilt in Shallot Plants.

&lt;b&gt;Background and Objective:&lt;/b&gt; &lt;i&gt;Fusarium oxysporum&lt;/i&gt; f. sp. &lt;i&gt;cepae&lt;/i&gt; (&lt;i&gt;Foc&lt;/i&gt;) causes &lt;i&gt;Fusarium&lt;/i&gt; wilt disease in shallots, with potential yield losses up to 50% if not properly managed. The widespread use of synthetic fungicides poses risks to human health and the environment. Binahong (&lt;i&gt;Anredera cordifolia&lt;/i&gt;) leaves contain antifungal secondary metabolites and are a promising botanical alternative. Nano-sizing such plant-based extracts may enhance their efficacy. This study aimed to assess the effect of nano-sized methanol extract of Binahong leaves on the &lt;i&gt;in vitro&lt;/i&gt; growth of &lt;i&gt;Foc&lt;/i&gt; and the severity of &lt;i&gt;Fusarium&lt;/i&gt; wilt in shallots and to compare it with the non-nano extract at higher concentrations. &lt;b&gt;Materials and Methods:&lt;/b&gt; The study involved both &lt;i&gt;in vitro&lt;/i&gt; and &lt;i&gt;in vivo&lt;/i&gt; experiments. &lt;i&gt;In vitro&lt;/i&gt; tests were arranged using a completely randomized design and &lt;i&gt;in vivo&lt;/i&gt; experiments followed a randomized complete block design with four replications. Treatments included nano Binahong methanol extract at 0, 1,250, 2,500, 5,000 and 10,000 ppm; non-nano extract at 20,000 ppm and the synthetic fungicide mancozeb (1 g/L) as a standard. Key parameters measured included colony growth, conidial germination, disease incidence and disease intensity. Data were statistically analyzed using ANOVA at a significance level of 5% (p<0.05). &lt;b&gt;Results:&lt;/b&gt; Nano Binahong extract significantly outperformed the non-nano extract in inhibiting &lt;i&gt;Foc&lt;/i&gt; growth and suppressing disease development. At 1,250 ppm, it caused the highest inhibition of colony growth (37.77%) and conidial germination (90.52%), compared to 26.66 and 88.36% inhibition, respectively, by the non-nano extract at 20,000 ppm. The same nano concentration (1,250 ppm) reduced &lt;i&gt;Fusarium&lt;/i&gt; wilt incidence and intensity in shallots by 92.36%, the highest among all treatments. &lt;b&gt;Conclusion:&lt;/b&gt; Nano methanol extract of Binahong leaves is highly effective in controlling &lt;i&gt;Foc&lt;/i&gt; and reducing &lt;i&gt;Fusarium&lt;/i&gt; wilt in shallots, even at much lower concentrations than the non-nano extract. This indicates its potential as an efficient, eco-friendly alternative to chemical fungicides. Future studies should explore its field application and formulation stability.