Determination of the Chemical Composition and Antifungal Activity of Wood Vinegar (Pyroligneous Acid) Against the Onion Bulb Rot Disease Caused by Fusarium proliferatum

Wood vinegar, also known as pyroligneous acid (PA), is a liquid mixture with organic properties that results from the condensation of smoke produced by the charring or pyrolysis of wood and its residues during processing. The aims of this study were to determine the chemical composition and antifungal activity of three different PAs obtained from the pyrolysis of apricot kernels (AKPA), hazelnut shells (HSPA), and kermes oak (OPA) against Fusarium proliferatum. As a result of GC-MS analysis, o‑guaiacol (18.98–26.18%), creosol (11.08–16.38%), syringol (6.35–8.67%), p‑ethylguaiacol (5.53–10.04%), o‑creosol (4.0–10.33%) and phenol (2.34–7.90%) were identified as the main constituents of the tested PAs. AKPA was the most effective PA among the tested treatments, with MIC values of 3.5 µl ml⁻¹ for mycelial growth and 1.0 µl ml⁻¹ for conidial germination. Of the treatments tested under in vivo conditions, AKPA completely inhibited disease incidence at a concentration of 7.5 µl g⁻¹ soil. HSPA and OPA, on the other hand, significantly suppressed disease incidence at concentrations of 10.0 µl g⁻¹and 12.5 µl g⁻¹ soil, respectively. All PA samples with MIC values caused significant deterioration of the morphological structures of the fungal hyphae. Since PAs showed promising antifungal activities against F. proliferatum both in vitro and in vivo, they could be used as a cost-effective natural product as an environmentally friendly alternative to synthetic fungicides.