Discovery of Erysiphe platani anamorph on Platanus xhispanica from Brazil

Platanus xhispanica (syn. P. acerifolia) is a Northern hemisphere plant which, along with other Platanus spp., is used as an urban shade tree in many cities throughout the world. In February of 2005, leaves of P. xhispanica showing typical symptoms of a powdery mildew were collected along the main street of Poços de Caldas, Minas Gerais, Brazil.

Young leaves were curled, deformed and partially covered by an amphigenous white powdery fungus. Mycelium was superficial, branched, septate, hyaline, 2.5 - 6.5 µm diameter; appressoria lobed, single or paired; conidiophores erect, cylindrical, 81.5 - 266 x 5.5 - 9 µm, unbranched, hyaline, smooth; conidia single or in short chains (2 - 3), doliiform, 26 - 38, 5 x 14 - 20 µm, hyaline often with a wrinkled appearance. Conidial base truncate and apex rounded in primary conidia, and both base and apex truncate in secondary conidia; germ tube forming a terminal lobate appressorium (Fig. 1). Teleomorph not found.

Based on these characteristics the fungus was identified as Erysiphe platani (Howe) U. Braun & S. Takam. (syn. Microsphaera platani). A sample was deposited in the herbarium of the Universidade Federal de Viçosa (VIC 30463). Although the superficial mycelium and conidiophores of the specimen from Poços de Caldas are narrower than those described in the literature for this species, the remaining features conform to previous descriptions of E. platani (Braun, 1987; Pastircakova and Pastircak, 2006). This species was first recorded in the USA, but recent reports from Slovakia (Pastircakova and Pastircak, 2006) and China (Liang et al. 2007) indicate it is becoming widespread throughout the world. In South America it was previously only recorded from Argentina and Chile (Pastircakova and Pastircak, 2006). This is, however the first record of E. platani on P. xhispanica from Brazil.

The specimen from Poços de Caldas, was heavily hyperparasitised by Ampelomyces quisqualis Ces. This observation was also noted by Liang et al. (2007) and Pastircakova and Pastircak (2006). Seemingly E. platani is highly susceptible to A. quisqualis and perhaps this might represent an option for controlling epidemics of E. platani.