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The current pandemic of the SARS-CoV-2 virus requires measures to reduce the risk of infection. In addition to the usual hygiene measures, air cleaners are a recommended solution to decrease the viral load in rooms. Suitable technologies range from pure filters to inactivating units, such as cold plasma or UVC irradiation. Such inactivating air cleaners, partly combined with filter technology, are available on the market in various designs, dimensions and technical specifications. Since it is not always clear whether they may produce undesirable by-products, and the suitability for particular applications cannot be assessed on the basis of the principle of operation, the effectivity of six inactivating devices was investigated in a near-real environment. The investigations were based on a standard method published by the VDI. The procedure was extended in such a way that a permanent virus source was simulated, which corresponds to the presence of a person suffering from COVID-19 in a room. The study addresses the difference of the mere presence of viruses to the determination of the virulence. As a result, a deep understanding is provided between the behavior of a virus as a pure aerosolized particle and its real infectivity in order to enable the assessment of suitable air cleaners.

Phylogenetic and morphological analyses have been conducted on powdery mildew specimens on different Berberis and Mahonia spp. from Asia, Europe and North America. The present study showed that collections of Erysiphe berberidis exhibit a high degree of morphological plasticity of the sexual morph, in contrast to their morphologically, rather uniform, asexual morph. In phylogenetic tree, all sequences cluster in a large strongly supported clade, without any indication and support for further differentiation into cryptic species. There are three morphological types within E. berberidis s. lat. that contain consistent differences. Until future multi-locus analyses will be available, we prefer to treat these ‘morphological types’ as varieties. These include Erysiphe berberidis var. berberidis, E. berberidis var. asiatica, and E. berberidis var. dimorpha comb. nov. (≡ Microsphaera berberidis var. dimorpha, M. berberidicola, and M. multappendicis). To fix the application of species name E. berberidis, an appropriate epitype was designated, with an ITS sequences.