For the years 2012–2018, we investigated the occurrence of storage diseases caused by fungi on four cultivars of apples grown in the central part of Poland. The fruits were picked in orchards managed with Integrated Pest Management (IPM) practices and stored in a cold room for 5–7 months. Depending on the season, apple cultivar and localization of orchard, the incidence of diseases was different. On apple cvs “Gala”, “Ligol” and “Golden Delicious”, bull’s eye rot (Neofabraea spp.) was the most frequently observed disease, whereas on apple cv. “Gloster”, gray mold (Botrytis cinerea) predominated. The blue mold (Penicillium expansum), brown rot (Monilinia spp.) and fungi of Alternaria spp. occurred at significantly lower intensity. We detected the occurrence of the new storage diseases of apples caused by Colletotrichum spp., Neonectria ditissima and Diaporthe eres.

The identity of the re-isolated fungus was confirmed as S. vesicarium, satisfying Koch's postulates. To the best of our knowledge this is the first report of S. vesicarium causing brown spot of pear in Poland.

The cultivated apple (Malus × domestica Borkh.) is the most economically important crop in Poland, the largest producer of apple fruits in Europe. During the growing season of 2024, typical symptoms of branch cankers and scaling-off of the bark were observed on the 24-year-old and over 60-year-old apple trees in the historical garden located in Nieborów, Lodzkie voivodeship. Fungi with greyish mycelium were repeatedly isolated from the interior of symptomatic branches. Based on cultural and morphological characteristics and DNA sequence data comparisons for ITS rDNA and translation elongation factor 1-alpha (EF1-α) regions, the causing fungus was identified as Diplodia bulgarica. Pathogenicity tests were performed on apple trees cv. ‘Najdared’, by inoculating them with mycelial plugs. All examined strains caused necrotic lesions on the leader, leading to the death of the whole tree, confirming the pathogenicity of the studied fungal isolates toward the apple tree.

This study aimed to isolate and evaluate bacterial strains with the potential to control storage diseases of apple trees. A total of 2,027 bacterial isolates were obtained from the phyllosphere of apple, strawberry, raspberry, and grape plants, as well as from soil associated with apple, strawberry, and raspberry crops. Screening using a dual-plate confrontation assay identified 1,678 isolates with antagonistic activity against Botrytis cinerea , the causative agent of grey mold. Subsequent testing on apple fruit enabled the selection of 13 isolates exhibiting the highest biocontrol efficacy. These isolates were identified as belonging to the species Serratia inhibens (22ZK, 24PK, 132M), Pseudomonas laurylsulfativorans (131M), Pseudomonas alvandae (133M), Pantoea agglomerans (T16/8, M13/07), Pantoea allii (T14/15, T08/33, T08/48), and Pantoea ananatis (T5/1, T14/1A, T14/8). The five most effective isolates (T5/1, T14/15, T16/8, T14/1A, and M13/07) reduced disease severity by 62.4% to 78.6%.Further antagonism assays against revealed that the selected isolates, besides B. cinerea also strongly inhibited growth of Monilinia fructigena and Colletotrichum acutatum in vitro.Pathogenicity tests confirmed that none of the 13 isolates induced hypersensitive reactions on tobacco or caused rot in potato tissues. However, five isolates (T08/33, T08/48, T5/1, T14/8, and T14/1A) were pathogenic in the red onion scale assay.