First report of Botryosphaeria dothidea associated with dieback of aspen ( Populus tremula ) in Italy

Abstract

In the summer of 2007, a dieback was observed on European aspen (P.tremula) growing in a nature reserve in Catania province, Sicily,Italy. Trees showed decline symptoms of yellowing, wilting and browningof the leaves, followed by leaf drop. The dieback was associatedwith cankers on the branches or trunk. More than 30% of the treeswere affected; most were approximately 20 years old, with a few treesmore than 100 years old showing symptoms. A fungus was constantlyisolated from affected bark incubated on potato dextrose agar. Thecolonies were fast-growing, with immersed light-brown mycelium bearingaggregated dark-brown to black pycnidia, up to 300 µm in diameter.The conidia were aseptate, smooth and fusiform. The fungus was identifiedas Fusicoccum aesculi, the anamorphic state of B. dothidea. Thisis thought to be the first report of this organism on European aspenin Italy.