Eutypella parasitica and Other Frequently Isolated Fungi in Wood of Dead Branches of Young Sycamore Maple (Acer pseudoplatanus) in Slovenia

Abstract

Eutypella parasitica R.W. Davidson and R.C. Lorenz is the causative agent of Eutypella canker of maple, a destructive disease of maples in Europe and North America. The fungus E. parasitica infects the trunk through a branch stub or bark wound. Because the fungal community may have an impact on infection and colonization by E. parasitica, the composition of fungi colonizing wood of dead branches of sycamore maple (Acer pseudoplatanus L.) was investigated in five sampling sites in Slovenia. Forty samples from each sampling site were collected between the November 2017 and March 2018 period. Isolations were made from the wood in the outer part of dead branches and from discoloured wood in the trunk that originated from a dead branch. Pure cultures were divided into morphotypes, and one representative culture per morphotype was selected for further molecular identification. From a total of 2700 cultured subsamples, 1744 fungal cultures were obtained, which were grouped into 212 morphotypes. The investigated samples were colonized by a broad spectrum of fungi. The most frequently isolated species were Eutypa maura (Fr.) Sacc., Eutypa sp. Tul. and C. Tul., Fusarium avenaceum (Fr.) Sacc., Neocucurbitaria acerina Wanas., Camporesi, E.B.G. Jones and K.D. Hyde and E. parasitica. In this study, we distinguished species diversity and the fungal community. There were no significant differences in the diversity of fungal species between the five sampling sites, and branch thickness did not prove to be a statistically significant factor in fungal species diversity. Nevertheless, relatively low Jaccard similarity index values suggested possible differences in the fungal communities from different sampling sites. This was confirmed by an analysis of similarities, which showed that the isolated fungal community distinctly differed between the five sampling sites and between the different isolation sources. Eutypella parasitica was isolated from all five investigated sampling sites, although Eutypella cankers were observed in only three sampling sites, indicating the possibility of asymptomatic infection.

In Vitro Interactions between Eutypella parasitica and Some Frequently Isolated Fungi from the Wood of the Dead Branches of Young Sycamore Maple (Acer pseudoplatanus)

“…Based on the obtained AI values, we assume that E. parasitica is usually a weak competitor compared to other fungal species which are present in the dead branches of A. pseudoplatanus. This is consistent with our previous results [27], where the quick progression of E. parasitica from the wood of the outer part of the dead branch into the wood of the trunk was observed. However, the outcome of interactions in nature varies depending on the size and quality of the resource, i.e., wood and microclimate [12].…”

“…The dual culture technique was used to test the possible antagonistic effect of ten fungal isolates isolated from the wood of the dead branches of A. pseudoplatanus [27] against an isolate of E. parasitica (ZLVG 805, see Table 1). The reference isolate of E. parasitica was obtained from Eutypella canker of maple (46.0533 • N, 14.4914 • E, 338 m a.s.l.)…”

“…A total of interactions were examined, including the self-inhibition assays and control pairings. ZLVG 799 7 1 The ten most frequently isolated fungi from the wood of the dead branches of A. pseudoplatanus [27] as challenge isolates and the response isolate of E. parasitica. 2 ZLVG-Culture collection of the Laboratory of Forest Protection at the Slovenian Forestry Institute.…”

“…P. Karst. are some of the most frequently isolated species from the wood of the dead branches of young sycamore maple [27]. However, little is known about how they interact and compete for the same substrate.…”

“…The aim of the present study was to investigate the in vitro activity of the ten most frequently isolated fungal species from the wood of the dead branches of Acer pseudoplatanus L. [27] against E. parasitica in dual culture experiments.…”