Erysiphe azaleae (Braun) Braun & Takamatsu, 2000
Rhododendron spec. (cult.), Belgium, prov. Antwerp, Oelegem, Vrieselhof © Carina Van Steenwinkel
especially the young fruits are heavily attacked
conidiophore wth characteristic bend in the basal cell
mycelium amphigenous. Appressoria nipple-shaped to lobed, single or paired. Conidia solitary, without fibrosin bodies, long-elliptic. Foot-cell of conidiophore usually sinuous. Cleistothecia with 4-10 asci, containing 4-6 spores. Appendages 10-40, equatorial, 1-1.5 the diameter; stiff, maximally 1 sept near the base, apically several times bifurcating in quick succession.
Also on all sorts of Rhododendron cultivars.
according to Klenke & Scholler no cleistothecia are formed on Calluna and Erica. At the same time the fungus causes on these plants malformations and premature leaf fall. Moreover, the infestations of Rhododendron appeared in Europe only since 1999 (and currently are spreading rapidly), while those of Calluna and Erica have been described well before 1900. For these reasons they believe that a discrete species is involved, viz. Oidium ericinum Eriksson, 1885. See however e.g. Braun ao (2003a) for a contrary opinion.
Apine, Bankina, Nikolajeva & Tomsone (2013a), Bacigálová & Marková (2006a), Beenken & Senn-Irlet (2016a), Braun (1995a), Braun & Cook (2012a), Braun, Cunnington, Brielmaier-Liebetanz ao (2003a), Bresinsky (2016a), Celar & Valič (2005a), Jage, Klenke & Kummer (2010a), Henricot (2009a), Klenke & Scholler (2015a), Kruse (2014a, 2019a), Lebeda, Sedlarova, Jankovsky & Shin (2007a), Mułenko, Piątek, Wołczańska ao (2010a), Piątek (2003b), Roques, Cleary, Matsiakh & Eschem (2017a), Talgø, Sundheim, Gjærum ao (2010a), Werner & Karolewski (2010a).