Acta Hortic. 1243. ISHS 2019. DOI 10.17660/ActaHortic.2019.1243.10 Proc. II Int. Symp. on Bacterial Canker of Kiwifruit Eds.: F. Spinelli, I. Donati and A. Cellini 59 Influence of cultural practices on the incidence and severity of kiwifruit bacterial canker I. Donati 1 , S. Mauri 1 , A. Cellini 1 , G. Buriani 1 , L. Fiorentini 1 , G. Costa 1 , S. Graziani 2 and F. Spinelli 1 1 Department of Agricultural Sciences, Alma Mater Studiorum, University of Bologna, Italy 2 ; Agrintesa soc. coop. Agricola, Faenza RA, Italy. Abstract Italy has a preeminent rank in kiwifruit industry, being the first exporter and the second largest producer after China. However, in the last years kiwifruit yields and the global cultivated area considerably decreased, due to the pandemic spread of the bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa). Several climatic conditions and cultural practices affect the development of the bacterial canker. With the emergence of this devastating disease, the use of pesticides rapidly increased and therefore the kiwifruit quality can be maintained only by ensuring agricultural practices that reduce the need of toxic xenobiotic compounds. This research work focused on the impact of agricultural practices on disease development and spread. High nitrogen fertilization, iron deficiency and water stress were related to more severe symptoms. Open canopies allow a better irradiation, aeration, and penetration of phytosanitary treatments. Synthetic gibberellins reduced disease incidence and severity in controlled conditions. Finally, the preliminary guideline harmonizing the best cultural practices with the current disease control inputs is provided. Keywords: Pseudomonas syringae pv. actinidiae, disease, agricultural practices INTRODUCTION The bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa), is considered the most dangerous disease of kiwifruit (Donati et al., 2014), affecting all the cultivated varieties of Actinidia deliciosa and A. chinensis. With the emergence of this devastating disease, the use of pesticides rapidly increased and therefore the kiwifruit quality can be maintained only by ensuring agricultural practices that reduce the need of toxic xenobiotic compounds. Disease development is related to climatic and environmental conditions (Vanneste et al., 2011), and nutritional imbalances, affected by fertilization and leaf/fruit ratio, may promote pathogen growth or depress plant defenses (Snoeijers et al., 2000). Chemical control, accompanied by a good orchard hygiene and an appropriate field management can help to contain disease spread. Therefore, a combination of cultural practices, such as different training and pruning systems, fertilization and use of bioregulators might influence the disease development and spread. The role of agricultural practices on bacterial canker incidence and development was studied to define the proper orchard management practices, minimizing disease incidence and severity. MATERIALS AND METHODS Plant material The experiments in controlled condition were performed on 30 cm tall potted A. deliciosa (‘Hayward’) plants. The plants were kept at 60% relative humidity (RH), 22°C and with a light-dark cycle of 16:8 h. In vitro experiments micropropagated A. deliciosa (‘Hayward’) plants were maintained on M&S base medium (Murashige and Skoog, 1962). The field trials were performed in commercial orchards, on approximately 10 years old A. deliciosa (‘Hayward’) and A. chinensis (‘Hort16A’ and ‘Jintao’) plants. Standard fertirrigation was