First report of powdery mildew of Platanus × acerifolia and P. occidentalis caused by Erysiphe platani in Greece.
In June 2012, typical symptoms of a powdery mildew were detected on all sycamores (Platanus occidentalis) along a central avenue of Heraklion (Crete, Greece), with the disease affecting approximately 80% of the leaves of all infected trees. In August 2013, similar symptoms were observed on 20% of the leaves of all three London planes (P. acerifolia) in a small grove in the Vrysses area of Lasithi (Crete, Greece). In both cases, the disease was severe, with white superficial colonies developing amphigenously on leaves, twigs, floral peduncles, inflorescences and fruits. The colonies were initially distinct and circular but gradually enlarged and often coalesced to cover the entire leaf blade. Young leaves appeared curled and chlorotic, occasionally leading to defoliation. The causal pathogen was identified as Erysiphe platani based on morphological, genetic (ITS) and pathogenicity analyses. This is thought to be the first report of E. platani causing disease of P. occidentalis and P. acerifolia in Greece.