A total of 103 tree and shrub samples infected with powdery mildew were collected during 2002–2019 from locations within parks, botanical gardens and urban green areas within the Czech Republic and the powdery mildews were morphologically analyzed and identified. The most frequently represented genera were: Erysiphe (27, including former genera Microsphaera and Uncinula), Podosphaera (11, including former genus Sphaerotheca), Phyllactinia (3), Sawadaea (2) and Arthrocladiella (1). New records for the Czech Republic were: E. (U.) arcuata, E. (M.) deutziae, E. (M.) euonymicola, E. (U.) flexuosa, E. (M.) platani, E. (M.) symphoricarpi, E. (M.) vanbruntiana var. sambuci-racemosae, E. (U.) ulmi, Po. amelanchieris, Po. (Sph.) pruinosa and Po. (Sph.) spiraeae. The results were compared with the spectrum of powdery mildew species in the surrounding countries (Slovakia; Hungary; Poland and Germany (Bavaria)).

Powdery mildews on the Asteraceae family were surveyed during 2007–2015 in the Czech Republic with the aim to increase our knowledge about occurrence, morphological characteristics and host specificity of powdery mildews on this family. In total, 32 host species with symptoms of powdery mildew were collected, and the fungal species were identified based on microscopic observations. These showed great variability in their morphological characteristics. Our study confirmed the high host specificity of powdery mildew species to their original hosts. A deeper knowledge of the taxonomy of the Asteraceae has brought substantial changes in the delimitation of powdery mildew species. In particular, delimitation of the three varieties of Golovinomyces asterum was studied and discussed.

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