ORIGINAL ARTICLE https://doi.org/10.1007/s10341-018-0373-y Erwerbs-Obstbau Comparison of Climate Change Effects on Pome And Stone Fruit Phenology Between Balkan Countries and Bonn/Germany Pakeza Drkenda 1 · Osman Musić 1 · Slađana Marić 2 · Darko Jevremović 2 · Sanja Radičević 2 · Metka Hudina 3 · Sabina Hodžić 4 · Achim Kunz 5 · Michael M. Blanke 5 Received: 7 February 2017 / Accepted: 22 December 2017 © Springer-Verlag GmbH Deutschland, ein Teil von Springer Nature 2018 Abstract The objective of the joint project between the two universities of Bonn and Sarajevo was to study the effects of climate change associated with warmer winter and spring temperatures on fruit tree phenology. Changes in flowering date of apple and cherry were correlated with local weather data obtained concomitantly on-site at four locations in the Balkan countries Slovenia, Serbia, B & H and at Bonn, Germany. Phenological data of flower opening (F1; BBCH 61) of apple cv. ‘Golden Delicious’ originated from 55 years at Cacak (44°N, Serbia) and at Klein-Altendorf, University of Bonn (50°N), cv. ‘Bobovec’ from the University of Ljubljana (46°N, Slovenia) and cherry cv. ‘Burlat’ (35 years at Klein-Altendorf, 50°N) and 20–30 years at Tuzla (44°N, B & H) and Mostar (43°N, Bosnia & Herzegovina; B & H). The annual precipitation showed a negligible change in the last 55 years of ±5% in the Balkan countries (e.g. Cacak, 699mm), but only ±1.8% at Klein-Altendorf (605mm) with a slight shift to more winter rainfall. Regression analysis showed an increase in mean temperature of 1.7°C (annual) and 1.45°C for the vegetation period at Klein-Altendorf (last 55 years), Germany. In the evaluated Balkan stations, the greatest increase in annual air temperature between two climate phases (until 1987 versus from 1988 until now) was at Ljubljana (1.4°C) and Cacak (1.2°C) in contrast to the least increase (0.3°C) at Tuzla (annual average 10°C) and an intermediate value (0.9°C) in the warmer Mostar (annual average 14.5°C). This recent temperature increase advanced flower opening by 10–14 days for apple such as cv. ‘Golden Delicious’ at Cacak and 7–10 days (last 55 years) at Bonn and 4–5 days (last 35 years) for the early cherry cv. ‘Burlat’ at Klein-Altendorf/Bonn; at Mostar and Tuzla, the effect of climate change was greater with the early cherry cv. ‘Burlat’ (26 days) compared with the difference of the late cherry cultivar (16 days). Before recent climate change (1973–1987), cherry flower was advanced by 10 days in the warmer med climate at Mostar but delayed by 16 days in the cooler Tuzla. The results, i.e. the flower advancement in the Continental climate but flower delay in the med climate, are discussed with respect to the risk of late frost and countermeasures to combat climate change effects. Keywords Apple (Malus domestica L.) · Balkan states · Burlat · Cherry (Prunus avium L.) · Climate change · Flowering · Frost · Global warming · Phenology  Pakeza Drkenda p.drkenda@ppf.unsa.ba Michael M. Blanke mmblanke@uni-bonn.de 1 Faculty of Agriculture and Food Sciences, University of Sarajevo, Sarajevo, Bosnia and Herzegovina 2 Fruit Research Institute Cacak, Cacak, Serbia 3 Biotehnical Faculty, University of Ljubljana, Ljubljana, Slovenia 4 The Hydrometeorological Institute of Federation of Bosnia and Herzegovina, Sarajevo, Bosnia and Herzegovina 5 INRES-Gartenbauwissenschaft, University of Bonn, Auf dem Hügel 6, 53121 Bonn, Germany K