First report of powdery mildew caused by Erysiphe platani on Platanus×acerifolia in Rio Grande do Sul, Brazil.
Platanus × acerifolia (London planetree) is a tree commonly used as an ornamental and in the furniture industry. In the summer of 2013, powdery mildew was observed on shoots of P. × acerifolia plants in the cities of Pelotas and Canela (State of Rio Grande do Sul, Brazil). Dense white powdery masses of conidia and mycelium were observed on leaves (abaxial and adaxial surfaces), petioles, and young stems. Leaves with high disease severities (≥70%) were deformed with curved edges to the adaxial side, and they often died. Based on morphological characteristics, sequence analysis of the DNA internal transcribed spacer region and pathogenicity tests, the causal agent was identified as E. platani. This fungus has been previously reported on P. × acerifolia in the city of Poços de Calda, state of Minas Gerais, Brazil, and on Platanus occidentalis in Korea. This is thought to be the first record of E. platani on P. × acerifolia in Rio Grande do Sul.