Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), threatens banana and plantain production throughout South America. Because Colombian biosafety regulations restrict in vitro work with Foc TR4, we tested the antifungal activity of Nostoc commune against F. oxysporum race 2 isolated from cv. ‘Manzano’ (Musa AAB). An ethanolic extract of the cyanobacterium (EEC) was profiled by gas chromatography and evaluated with a Kirby–Bauer assay (1000–4000 ppm; n = 4). Synthetic Sico^® and botanical Timorex^® served as positive controls, and solvent-free plates were the negative control. Growth reduction (GR) and percentage inhibition of radial growth (PIRG) were analysed with Student’s t-test (α = 0.05). Forty-two compounds—mainly fatty and carboxylic acids associated with antifungal activity—were detected. Sico achieved complete inhibition (100 ± 0%), Timorex suppressed 76 ± 2%, and 4 000 ppm EEC curtailed mycelial expansion by 45 ± 3% (p < 0.01). Although less potent than commercial fungicides, EEC impeded F. oxysporum growth, demonstrating that N. commune synthesises bioactive metabolites. Optimising cyanobacterial cultivation and formulation could yield a sustainable biocontrol alternative for managing Fusarium wilt in the region.

Plantain (Musa paradisiaca) is a climacteric fruit with high endogenous ethylene production, which accelerates ripening and limits shelf life, especially during transport and exportation, leading to significant losses for producers and distributors. This study evaluated the effect of gibberellic acid (GA₃) and zeatin (Zea) on delaying the ripening of Hartón plantains grown in Colombia. The goal was to assess whether these plant regulators could delay physicochemical changes under simulated cold chain conditions. A completely randomized design was used with nine treatments, plus a control, each with five replicates. Fruits were stored at 11 ± 2 °C and 75% relative humidity for 25 days. Pulp firmness, soluble solids, titratable acidity, pH, starch, chlorophyll, carotenoids, total polyphenols, and polyphenol oxidase activity were assessed. The combination of GA₃ + Zea was effective in preserving firmness, maintaining starch and chlorophyll content, and limiting increases in soluble solids and polyphenol oxidase activity associated with senescence. This delayed ripening did not affect structural integrity or caused oxidative stress. Combined application of GA₃ and Zea is a low-cost and effective strategy to extend the shelf life of plantains for export, benefiting the tropical agri-food chain. This approach offers a practical alternative for maintaining fruit quality without the need for costly preservation technologies.