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Limited data regarding the resources and methods used by organic fruit growers to learn about production practices are available, even though this information is crucial to improving the efficacy of knowledge transfer. Therefore, a survey to gain information from knowledge networks dealing with organic fruit production about their structural organisation, tasks and methods of communication was carried out in twenty-one countries from Europe and the Mediterranean basin. A total of 56 networks representing about 42,500 professionals were identified as a result of the survey. The vast majority of them were only active at the regional or national level and were composed of farmers, advisors and researchers. About 3/4 of the networks were developing improved strategies for agronomic practices and about half of them were also involved in different knowledge-transfer activities between their members. Personal contact was the most used method to exchange and disseminate information within the networks as well as to elaborate improved strategies. The findings were analysed in view of the methods and practices commonly used to share both explicit (scientific) and implicit (practical) knowledge among practitioners. It was concluded that knowledge networks play an important role in the development of more resilient organic cropping systems, frequently making organic fruit growers the drivers of innovation. Networking for knowledge exchange was considered a process that encourages the active involvement of farmers in experimentation and innovation applying a method of knowledge sharing that is rooted in the very foundation of organic philosophy. Some recommendations and future research were suggested to further foster the development and functioning of networks for knowledge exchange.

The aim of evaluations performed in experimental plantings of the Research and Breeding Institute of Pomology Holovousy Ltd. was to verify the effect of covering systems on fruit characteristics – size, weight, firmness and soluble solids content (SSC). The research was focused on evaluation of fruit characteristics in 2017 and 2018 on fourteen cultivars: ´Amid´, ´Cristiana´, ´Early Korvik´, ´Elza´, ´Fabiola´, ´Felicita´, Horka´, ´Justyna´, ´Kasandra´, ´Kordia´, ´Korvik´, ´Tamara´, ´Těchlovan´ and ´Vanda´. The tested cultivars were grown in an IPM irrigated covered orchard. The largest fruit size was recorded for the cultivar ´Tamara‘ with 29.5 mm followed by the cultivar ´Horka‘ with 29 mm and ´Felicita´ with 28.6 mm. The greatest weight was recorded for the cultivar ´Tamara‘ with 12.4 g followed by ´Felicita´ with 12.3 g. The greatest firmness was recorded in fruits of the cultivar ´Amid´ with index 77.5 and ´Tamara´ with index 73.2. High correlation between fruit characteristics was found only between weight and size of fruits (correlation coefficient 0.88). High differences were recorded between years. In 2017, fruits characteristics were higher (size 27.5 mm, weight 10.9 g, firmness 65.3, SSC 19.3 °Brix) while in 2018, fruit characteristics were lower (size 26.5 mm, weight 9.2 g, firmness 59.2, SSC 16.5 °Brix).

International audience; Apple scab, caused by Venturia inaequalis, is a major fungal disease worldwide. Cultivation of scab-resistant cultivars would reduce the chemical footprint of apple production. However, new apple cultivars carrying durable resistances should be developed to prevent or at least slow the breakdown of resistance against races of V. inaequalis. One way to achieve durable resistance is to pyramid multiple scab resistance genes in a cultivar. The choice of the resistance genes to be combined in the pyramids should take into account the frequency of resistance breakdown and the geographical distribution of apple scab isolates able to cause such breakdowns. In order to acquire this information and to make it available to apple breeders, the VINQUEST project (www.vinquest.ch) was initiated in 2009. Ten years after launching this project, 24 partners from 14 countries regularly contribute data. From 2009 to 2018 nearly 9000 data points have been collected. This information has been used to identify the most promising apple scab resistance genes for developing cultivars with durable resistance, which to date are: Rvi5, Rvi11, Rvi12, Rvi14 and Rvi15. As expected, Rvi1, together with Rvi3 and Rvi8, were often overcome, hence have little value for scab resistance breeding. Rvi10 may also belong to this group. On the other hand Rvi2, Rvi4, Rvi6, Rvi7, Rvi9, and Rvi13 are still useful for the breeding, but their use is recommended only in extended pyramids of (≥3) resistance genes.

The effect of ultra-low oxygen (ULO) conditions applied during long-term storage of apples to preserve content of phenolic compounds has been studied. Contents of phenolics including gallic acid, chlorogenic acid, epicatechin, quercitrin, rutin, phloridzin, and phloretin in ten apple cultivars were determined immediately after the harvest and their changes monitored after three, five, and seven months storage in a cooled warehouse and under ULO conditions. Fast HPLC separation with UV detection using core-shell C18 column and gradient elution was applied. Different apple cultivars were tested and statistical analysis performed based on multiple hypothesis t-test with p-value cut-off adjusted by Holm-Bonferroni method. Principal component analysis was applied to further support the observations. Our results proved the benefits of ULO storage conditions for cultivars intended for longer storage. However, ULO storage conditions did not have a significant effect during short-term storage. Most of the cultivars bred for short-term storage stored in cooled or ULO conditions did not exhibit any statistical difference in the phenolics content.