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Bacterial canker, caused by Pseudomonas syringae pv. syringae and pv. morsprunorum, is one of the most important diseases of stone fruit trees (Prunus spp.). The pathogen infects buds, flowers, fruitlets, leaves and shoots, from which the disease spreads to the branches, boughs and trunks, causing necrosis and cankers. The efficacy of different chemical and biological products for the control of bacterial canker on stone fruit trees was tested in 2018–2021. The experiments were conducted in sour cherry, plum and sweet cherry orchards in central Poland. Foliar application of the tested preparations was performed three times a season. The biological efficacy of the tested products in the control of bacterial canker was evaluated on sour cherry on the basis of infected leaves and fruits and on plum and sweet cherry on the basis of infected leaves. The highest efficacy was observed for products containing various forms of copper—copper oxide, copper oxychloride and copper hydroxide—as well as fertilizers with copper gluconate and the fungicide Luna Care 71.6 WG (fluopyram and fosetyl-Al). However, the biological preparations were significantly less effective. The conducted studies showed that preparations based on copper gluconate can be a valuable alternative to typical copper fungicides.

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.

Triggering the plant resistance induction phenomenon by chemical compounds, for example acibenzolar-S-methyl ester, has been known and described in scientific literature. Other benzothadiazole derivatives have been also described; however, their properties have not been sufficiently studied. The tested substance, N-methyl-N-methoxyamide-7-carboxybenzo(1.2.3)thiadiazole (BTHWA), is an amide derivative of benzothiadiazole, showing a stimulating effect on plant growth, apart from its plant resistance inducing activity. This article presents the impact of BTHWA, used solo and in the program with fungicides, on the strawberry plants development, fruits health, yield, and quality parameters of the crop. The results show that the combined use of BTHWA and fungicides had a positive impact on the plants health and fruit health and nutraceutical and nutritional composition of compounds when compared to the results obtained when strawberries were treated only with the BTHWA or the fungicide. As a result of BTHWA use, the partitioning of assimilates has changed, which directly translated into the results of the conducted experiments. A reduction in the respiration of the fruit during storage was also observed, possibly due to a reduced disease infestation and a lower dry matter content in the fruit. A correlation between the parameters determined during the experiment was found. The BTHWA mode of action was evidenced to be beneficial to strawberry plants and fruit.