Invasive Species Compendium

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Abstract

First record of Eutypella parasitica on Acer in Switzerland.

Abstract

In February 2021, a Eutypella canker was detected on a multi-trunked Acer pseudoplatanus in a private garden in Uster, Canton Zurich, Switzerland. The canker was located around 5 m above ground. A second canker, which had been partially removed during arboricultural care, was observed at the same height on another trunk of the same tree. Morphological examination revealed no ripe sexual fruiting bodies but genetic analyses of the ITS region confirmed the diagnosis. The tree was removed and incinerated. The forests closest to the site (located between 600 to 1400 m away) were surveyed but no further Eutypella cankers were found. In the course of the investigations, a previous report made in October 2014 on A. pseudoplatanus (Walenstadtberg, Canton St. Gallen, 980 m above sea level) by Prof. Dr. Ottmar Holdenrieder was discovered. The tree was living with a canker just above the base of the trunk. Ascospores were abundant. Although a herbarium record was filed, no scientific report was made. In September 2021, the area around the site in Walenstadtberg was searched. In the vicinity, at a distance of 23 and 200 m from the first record respectively, an infected A. pseudoplatanus (21 cm DBH) and A. platanoides (15 cm DBH) were found. Eutypella was genetically confirmed as no mature sexual fruiting bodies were present. Infected trees were removed in the winter of 2021/22 and sent for incineration. The forest was surveyed within a radius of 145 m around the two new findings but no other cankers were detected. The fungus Eutypella was isolated from the fruiting bodies and infected wood sampled from necrotic tissues around the canker collected in Walenstadtberg. n-rDNA-ITS sequencing showed 99-100% identity with E. parasitica type specimen. This is thought to be the first record of E. parasitica on Acer in Switzerland.