Antifungal Activity of Pyroligneous Acid Derived from Mahogany Sawdust Against Colletotrichum sp. on Papaya Fruit

Abstract

Mahogany (Swietenia sp.) processing generates a large volume of sawdust residues that remain underutilized despite their potential to be converted into value-added products within a circular forestry system. This study aimed to evaluate the antifungal activity of mahogany sawdust-derived pyroligneous acid (PA) against Colletotrichum sp., a major postharvest pathogen of papaya (Carica papaya L.). PA was produced through controlled pyrolysis at 400 °C for 90 min under limited-oxygen conditions. Antifungal activity was assessed using both in vitro and in vivo assays with PA concentrations of 0% (negative control), 1%, 3%, 5%, and 7%, alongside mancozeb at 1.5 g/L (positive control), arranged in a completely randomized design with five replicates per treatment. Data were analyzed using one-way analysis of variance followed by Duncan’s Multiple Range Test at a 5% significance level (p < 0.05). The results demonstrated that the 7% PA treatment delayed in vitro fungal growth until day 10, whereas growth in the negative control began on day 2, and reduced mycelial growth by 70.56%. In in vivo assays, the 7% PA treatment effectively suppressed anthracnose development, resulting in a disease inhibition rate of 47.77% and an area under the disease progress curve (AUDPC) of 297.98, which was significantly lower than that of the negative control (570.53). Although the positive control achieved complete in vitro inhibition and greater in vivo suppression (67.01%; AUDPC = 188.21), the 7% PA treatment exhibited strong dose-dependent antifungal activity, which may be associated with its high acetic acid content and low pH. Lower PA concentrations showed only partial and inconsistent inhibition. These findings indicate that mahogany sawdust-derived PA has considerable potential as a bio-based antifungal agent for postharvest disease management. Further studies on formulation optimization, product stability, and field-scale validation are recommended to support its practical application.

Keywords: anthracnose, Carica papaya, Colletotrichum, pyroligneous acid, Swietenia sp., wood vinegar