First report of Erysiphe corylacearum in Germany and Hungary
Native to East Asia, Erysiphe corylacearum is a new powdery mildew of hazelnuts (Corylus spp.) which was first observed in Türkiye in 2013 and has since rapidly extended its distribution range in the Middle East, the Caucasus, the Mediterranean as well as some countries in Eastern and Central Europe (EPPO RS 2021/042, RS 2021/049, RS 2021/249).
In Hungary, E. corylacearum was observed in a hazelnut (Corylus avellana) plantation and in a collection of different varieties of hazelnut of the Hungarian University of Agricultural and Life Sciences in Érd in August 2021. White patches of mycelium and conidia were observed on both side of the leaves. The disease incidence was 100% on varieties 'Segorbe', and 'Corabel', 70% on 'Ennis', and 30% on 'Istrska dolgoplodna leska' (15 plants per cultivar). On observed leaves, E. corylacearum occurred together with Phyllactinia guttata.
In Germany, the presence of E. corylacearum was recorded in 2021 and 2022 in Bavaria, Baden-Württemberg and Nordrhein-Westfalen in gardens, parks and forests. It was mainly found on Corylus avellana but also found once on C. avellana var. heterophylla and twice on C. maxima. Beenken et al. (2022) consider that the pattern and the speed of its spread suggest that E. corylacearum is not only spread by wind-borne conidia but is also transported by human traffic.
In Switzerland, the pathogen was first reported in urban areas, but it is now widespread, even in forests far away from settlements, and in the alpine region where it occurs at altitudes up to 1450 m.
Sources
Beenken L, Kruse J, Schmidt A, Braun U (2022) Epidemic spread of Erysiphe corylacearum in Europe–first records from Germany. Schlechtendalia 39, 112-118.
Kalmár K, Desiderio F, Varjas V (2022) First report of Erysiphe corylacearum causing powdery mildew on hazelnut in Hungary. Plant Disease (early view). https://doi.org/10.1094/PDIS-12-21-2737-PDN