Research and Science

During the first known outbreaks in the eastern USA, large numbers of planted Platanus trees, mostly P. x hispanica, were lost in cities over a 20 – 30-year period (Walter et al., 1952; Crone, 1962). In south-eastern France, around Marseille, thousands of street trees were killed by C. platani (Ferrari & Pichenot, 1974; 1976). The disease soon spread into the neighbouring department of Vaucluse, where an estimated 1,500 to 1,700 infected and adjacent trees were felled annually; more than 30,000 trees were removed in Provence Alpes Côte d’Azur over 25 years (Chapin and Arcangioli, 2007). More recently, the problem with the disease along a substantial part of the Canal du Midi, which connects the Atlantic Ocean to the Mediterranean Sea through western France, received media attention, not least because of the high costs of removal and replacement. Initial findings of C. platani were near Toulouse in the early 2000s (Bonnet and Collet, 2007), after which the pathogen spread quickly, possibly in the Canal du Midi itself. Along the Canal du Midi, some 10,000 to 13,000 trees were diagnosed as infected and felled (VNF, 2019).

The fungus spread from ports into the north of Italy in short time after introduction, killing many trees, particularly those newly planted along avenues (Panconesi, 1981; 1999). There was a big outbreak in and around Naples after the end of World War II, coinciding with American Service bases, with losses amounting to 90 % of street trees by the end of the 1980s (Panconesi, 1999). By that time, the disease was present throughout the Italian peninsula, affecting trees in all major cities (Panconesi, 1999).

The disease was discovered in natural stands of P. orientalis in Sicily in the late 1980s (Granata & Pennisi, 1989), and was soon followed by reports from Greece, probably arriving there in the late 1990s (Tsopelas & Angelopoulos, 2004). Platanus orientalis is a common, native tree in Greece, particularly in riparian zones. The pathogen established in the Peloponnesos, but rapidly spread into north-western Greece and, subsequently, beyond that region. The high level of susceptibility of P. orientalis to C. platani led to devastation of natural populations of the tree, and the spread into Albania (Tsopela et al. 2015), with significant mortality in natural ecosystems and cities, shows that it threatens other Balkan countries and countries to the east.

In Türkiye, further spread occurred into the European part of Istanbul, where Platanus are important planted trees in urban parks and streets (Lehtijärvi et al., 2018), presumably due to the import of infected trees.