Antifungal activity of non-thermal atmospheric pressure plasma against postharvest mango anthracnose, Colletotrichum siamense

Abstract

Anthracnose, caused by Colletotrichum siamense, is a major postharvest disease of mango (Mangifera indica L.), contributing to significant economic losses during storage and distribution. This study investigated the antifungal efficacy of non-thermal atmospheric pressure plasma (NTP) and plasma-activated water (PAW), generated using argon and helium gases, for the inactivation of C. siamense and the suppression of anthracnose symptoms in mango fruits. Complete inhibition of mycelial growth was observed following plasma exposure for up to seven days. Direct NTP treatments significantly reduced spore viability, with helium plasma achieving 18.53–49.00 % inactivation and argon plasma achieving 13.15–47.21 % based on spore counts. The highest reduction in viable colony counts (up to 97.34 %) was observed following 10 min of argon plasma exposure at a flow rate of 0.25 Lpm. PAW treatments also significantly reduced spore viability, with argon-based PAW showing greater antifungal activity (35.56–53.77 %) than helium-based PAW (19.44–41.39 %). At a flow rate of 0.25 Lpm and an exposure time of 10 min, PAW generated using argon and helium resulted in reductions in viable colony counts of 64.77 % and 72.35 %, respectively. Membrane integrity assays revealed increased leakage of UV-absorbing intracellular components, while fluorescence-based viability staining confirmed reduced spore viability following both treatments. Scanning electron microscopy further revealed spore surface deformation consistent with oxidative damage. In vivo assays on detached Nam Dok Mai and Chok Anan mangoes demonstrated significant suppression of anthracnose lesion development from both mycelia and spore inoculations, particularly during the later stages of incubation. These results indicate that NTP and PAW are promising chemical-free approaches for managing postharvest anthracnose in mango. Further studies are warranted to refine treatment conditions and to evaluate their compatibility with existing postharvest practices and their effects on fruit quality.