Pectinolytic bacteria of the family Enterobacteriaceae, specifically Dickeya solani, are known to cause potato blackleg. This study aimed to evaluate the effectiveness of a mixture of two bacteriophages from the genus Limestonevirus in controlling Dickeya solani in both greenhouse and field trials. The potential of bacteriophages for ecological potato control was also assessed. The phages φDs3CZ and φDs20CZ were isolated from soil in the Czech Republic between 2019 and 2021. They were applied preventively and curatively as a solution on artificially wounded and inoculated seed tubers immediately prior to planting. The phage-treated variant showed a highly significant reduction in the extent of D. solani infection compared to the untreated control in both the greenhouse and field trial. The effect of the phages depended on the concentration of the solution, the rate of tuber injury, and the sequence of application. When applied preventively, the phages caused a significantly higher reduction in the rate of blackleg symptoms (86.7% and/or 87.1%) compared to the curative application (54.6 and/or 36.6%). Phages φDs3CZ and φDs20CZ showed potential for use in biological potato control against Dickeya solani.

Potato silver scurf, caused by the fungus Helminthosporium solani, is an important storage disease of potato (Solanum tuberosum L.), reducing the market value of tubers. Using in vitro and in vivo assays, the presented experiments aimed to determine the effect of selected essential oils (EOs: α-pinene, carvacrol, cinnamaldehyde, D-carvone, eucalyptol, L-linalool, L-menthol, L-menthone, (R)-(+)-limonene, and thymol) on H. solani growth. All EOs inhibited pathogen growth, but their antifungal activities differed significantly. Thymol, carvacrol, and cinnamaldehyde had the strongest inhibitory effects on mycelial growth under in vitro conditions. (R)-(+)-limonene displayed the weakest inhibition. The effectiveness of those EOs with the greatest antifungal activity was confirmed by in vivo experiments. EOs were applied through dressing and fumigation, with EOs bound to a biopolymer for dressing. Dressing and fumigation brought a highly statistically significant reduction in H. solani infection intensity and sporulation intensity on tubers. Although EOs had an insignificant effect on potato cooking quality, the taste of EO-dressed tubers was degraded by an off-odor and off-taste. EOs could provide an ecological alternative for reducing H. solani tuber infection during storage.

Fusarium dry rot of potato may be caused by several species of the genus Fusarium. This study aimed to evaluate the effect of essential oil (EO) components (α-pinene, carvacrol, cinnamaldehyde, D-carvone, eucalyptol, L-linalool, L-menthol, L-menthone, (R)-(+)-limonene and thymol) on the growth of Fusarium solani var. coeruleum using in vitro and in vivo experiments. All the evaluated EO components had a significant effect on the pathogen growth inhibition. Under in vitro conditions, the strongest inhibitory effect on mycelial growth was recorded for carvacrol, thymol, L-menthol and cinnamaldehyde. In vivo experiments confirmed the efficacy of selected EO components. The application of EO components was done by tuber dressing and fumigation. After treating tubers with EO components by dressing and fumigation, a statistically highly significant reduction in tuber infection with the pathogen was observed. Dressing usually had a stronger effect on the reduction in pathogen tuber infection (56.07–81.44%) compared to fumigation (40.03–69.63%). EO components did not have any significant effect on the organoleptic characteristics of cooked tubers; however, during tasting, a deteriorated quality of EO component-dressed tubers was found due to the off-odor and taste of the applied EO components. EO components have a high potential for ecological tuber protection against F. solani var. coeruleum during storage.