Possible impact of climate change on the occurrence and the epidemic development of cercospora leaf spot disease (Cercospora beticola sacc.) in sugar beets for Rhineland-Palatinate and the southern part of Hesse

In this study the possible impact of climate change on the occurrence of the Cercospora leaf spot disease (CLS) in sugar beet, triggered by the fungus Cercospora beticola sacc., and its regional differentiation in Southwest Germany was analyzed by means of the forecasting model CERCBET1. The model projects the day of the year (DOY) when 1 %, 50 % and 100 % of the fields in the region are potentially infested by Cercospora Leaf Spot disease (CLS1, CLS50 and CLS100). To run the disease model the data of the REgional climate MOdel REMO were used. The possible impact of climate change on the occurrence was studied comparing three time windows: baseline period ‘B′ (1971–2000), medium-term period ‘K‘ (2021–2050), long-term period ‘L‘ (2071–2100). In addition the ontogenesis of the young sugar beet plants was simulated using a leaf-growth model. The results of CERCBET1 and the leaf-growth model were compared to draw conclusions whether CLS potentially would occur in a different leaf stage. The dates of completion of the 20- and 40-leaf stage (B20 and B40) therefore were examined. The simulation results indicate an earlier CLS occurrence as well as an accelerated leaf growth due to the projected climate change. The disease might occur in earlier growth stages of the sugar beet plants. A possible consequence of the earlier CLS occurrence could be an increasing number of necessary fungicide applications also regarding the prolonged growing season. For period L, especially, projections are difficult to make due to the uncertainties of the archived breeding progress, particularly regarding the breeding for resistance, the development of fungicides and the future socio-economic development.