Erysiphe viburni Duby, 1830
on Viburnum
gall
mycelium amphigenous, at the upper side of the leaf more or less persistent. Appressoria lobed or multilobed, paired or single. Conidia solitary, elliptic, without fibrosin bodies. Cleistothecia 75-130 µm, with 2-8 asci containing 4-8 spores. Appendages 4-22, equatorial, 1-1.5 x the diameter; they are stiff, extending, brown at the base, have 0-2 basal septa, the cell wall is rough; apically they are ± 4-5 times bifurcated in quick succession.
According to Klenke & Scholler conidia are formed only sparingly, and the cleistothecia are hypophyllous.
host plants
Adoxaceae, monophagous
Viburnum acerifolium, opulus, trilobum.
synonyms
Microsphaera sparsa Howe, 1872; ? Golovinomyces sparsus auct. nec (Braun) Heluta, 1988.
references
Braun (1995a), Braun & Cook (2012a), Bresinsky (2016a), Jage, Klenke, Kruse ao (2016a), Jage, Klenke & Kummer (2010a), Jage, Kruse, Kummer ao (2013a), Klenke & Scholler (2015a), Kozłowska, Mułenko & Heluta (2015a), Kruse (2014a, 2019a), Leysen (2017a), Scholler & Schubert (1993a).