trans-2-Octenal controls Fusarium oxysporum f. sp. lycopersici, the causal agent of tomato wilt in vitro, in soil and in the field.

Background: Fungal plant diseases cause major crop losses. Phytopathogenic fungi's ability to evolve resistance to fungicides, alongside ongoing prohibition of such agents by the European Commission because of their pronounced adverse effects on human health and the environment, make their control a challenge. Moreover, the development of less perilous fungicides is a complex task. Here we describe the process and challenges involved in the development of a novel fungicide, from in-vitro studies to field experiments.

Results: In-vitro experiments with trans-2-octenal, a bioactive compound secreted by the endophytic fungus Daldinia cf. concentrica, revealed its ability to fully inhibit and kill phytopathogenic microorganisms. A formulated version of trans-2-octenal was then used against the soil-borne pathogen Fusarium oxysporum f. sp. lycopersici (Forl), the causal agent of tomato vascular wilt disease, in pot experiments with different soil types. We found the highest fungicidal activity in sandy and loam soils, whereas heavy soil impaired activity. Lastly, we investigated the activity of the formulated trans-2-octenal against Forl in semi-field experiments. We achieved complete elimination of Forl, provided the soil is rotavated after trans-2-octenal application.

Conclusion: trans-2-Octenal has the potential to control Forl in vitro, in pots and in the field. © 2025 Society of Chemical Industry.