Potato gangrene is a very dangerous disease developing during storage and can lead to serious crop losses. The main control of this pathogen is reported by the post-harvest use of fungicides. However, the pathogen resistance to fungicides and public concerns about food safety require the search for new alternatives to fungicides, potentially less harmful to human health and the environment. The antifungal influence of chitosan against Phoma exigua var foveata and analyzing its inhibitory effect on the gangrene of potato tubers were investigated. The results showed that the growth of the mycelium and the germination of Phoma spores were suppressed by chitosan treatment, and the inhibitory effect was strongly correlated with the chitosan concentration. The effectiveness of post-harvest chitosan treatment has been studied for induced resistance to Phoma rot in tubers of two potato varieties (Kolobok and Santa). In vivo studies have shown that chitosan treatment at a concentration of 0.5 or 1% effectively combated gangrene potato tubers inoculated with a suspension of Phoma spores. However, treatment with chitosan at a concentration of 1% caused phytotoxicity of potato tubers. Chitosan increased the activity of peroxidase, polyphenol oxidase and phenylalanine ammonia-lyase in tubers. This study suggests that the influence of chitosan may be related to the induced resistance of potato Phoma rot, and the use of chitosan may be a promising agent as a natural fungicide for partial replacement of synthetic fungicides to protect potato tubers during storage.

The antifungal activity of essential oils against Phoma exigua var foveata, was investigated by analyzing its inhibitory effect on the gangrene of potato tubers. The results showed that mycelium growth and spore germination of Phoma was suppressed by treatment with essential oils, and the inhibitory effect strongly correlated with the concentration of essential oils used in this study. The effectiveness of post-harvest treatment with essential oils was studied for induced resistance to Phoma rot in tubers of two potato varieties (Kolobok and Sante). The results showed the fungicidal effect of cumin and lavender essential oils against phomosis at concentrations of 0.1, 0.2, and 0.4, significant inhibition of mycelium growth (18.1-100%), and viability of conidia (12.8-100%) compared to the control. Moreover, both oils at a concentration of 0.4% caused 100% inhibition of mycelium growth and spore germination. Treatment with oils at a concentration of 0.01-0.04 l/t significantly reduced the degree of damage to tubers infected with phomosis. However, cumin essential oil at a concentration of 0.04 l/t had the greatest effect 97.1% compared to lavender oil 95.4%.