Impact

Ecological Impacts

C. corticale has been for some years a big threat to maples (Acer spp.) through Europe with continuous new records of damages (Bußkamp et al., 2024). The most susceptible genus to SBD is Acer and within Europe A. pseudoplatanus and A. platanoides are notoriously associated with SBD outbreaks. In addition, many other fungal and oomycete pathogens are known to affect the vitality of maple such as Nectria (Hiemstra 1998; Račko et al., 2022), Verticilium dahliae (Sinclair et al., 1981; Brglez et al., 2024), Eutypella parasitica (Cech et al., 2016; Brglez et al., 2020) or Phytophthora spp. (Ginetti et al., 2014; Milenković et al., 2014). A. pseudoplatanus is native to Central Europe and typical in mixed forests with high requirements of nutrients and water supply while A. platanoides is more modest in terms of needs.

Economic Impacts

C. corticale in an endophytic stage should not affect the wood quality of as shown in the studied areas by Schlößer et al. (2023). In contrast, when the fungal becomes pathogenic and tongue-shaped necroses are developed on the surface of the trunk, typical extensive greenish-grey wood discoloration and wood rot are observed in the inner trunk after felling the trees. That implies a complete devaluation of the trunk wood (Grüner et al., 2020; Kesphol et al., 2022). For the moment, SBD has been prevalently reported from municipal areas (e.g. Gregory and Waller, 1951; Bencheva, 2014; Koukol et al., 2015). It is probably due to higher air temperature in cities and higher incidence of wounds acting as infection gates. Therefore, the high occurrence of SBD in public green enhances the cost for its maintenance and management.

Social Impacts

The conidia of C. corticale, which are produced in vast masses up to 170.000.000 spores/cm² (Gregory and Waller 1951; Bork, 2018), have a particular impact on human health. These spores are the causal agent of the maple bark disease (MBD) (Emanuel et al., 1962), or also defined by WHO as Maple Bark Stripper Lung (WHO, 2022). It is hypersensitivity pneumonitis caused by inhalation of the spores with symptoms such as allergic asthma, flu-like infections and interstitial pneumonia (Braun et al., 2021). This disease is a hazard for those occupations such as arborists, gardeners, woodman, foresters, sawyers or paper mill workers who are exposed to the spore inhalation for long periods due to activities such as removing and handling infected wood. Occasional recreational activities in areas with SBD and limited exposure to the spores are considered a low health risk for most people (Braun et al. 2021). The first cases were already mentioned in 1932 and it was defined as a diffuse lung disease affecting lumber workers peeling the trunk of diseased maples in the USA (Towey et al., 1932). Later, in 1962, it was described in detail as the maple bark disease (MBD) (Emanuel et al., 1962). Upon a proper diagnosis and therapy in time, the recovery from MBD is complete, but chronic disease could lead to lung fibrosis and death (Braun et al., 2021). It is therefore recommended to wear personal protective equipment (goggles, particle filtering respiratory systems FP3, Protective suit with hood, protective gloves and boots) to avoid direct contact with spores of C. corticale for occupation (Niesar et al., 2020; Braun et al., 2021; Burgdorf et al., 2023). Furthermore, felling of the affected trees should be done with a harvester and not with a chainsaw to avoid closer contact with the spores (Burgdorf et al., 2023).