Plant Parasites of Europe

leafminers, galls and fungi

Erysiphe azaleae

Erysiphe azaleae (Braun) Braun & Takamatsu, 2000

on Ericaceae

Erysiphe azaleae on Rhododendron spec. (cult.)

Rhododendron spec. (cult.), Belgium, prov. Antwerp, Oelegem, Vrieselhof © Carina Van Steenwinkel

Erysiphe azaleae on Rhododendron spec. (cult.)

especially the young fruits are heavily attacked

Erysiphe azalea: conidiophore

conidiophore wth characteristic bend in the basal cell

Erysiphe azalea: germinating conidium

germinating conidium



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.

host plants

Ericaceae, oligofaag

Calluna vulgaris; Erica carnea, x darleyensis, erigena, gracilis, x hiemalis, subdivaricata, vagans; Rhododendron arborescens, canadense, japonicum, luteum, molle, mucronatum, occidentale.

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), Ruszkiewicz-Michalska & Michalski (2005a), Talgø, Sundheim, Gjærum ao (2010a), Werner & Karolewski (2010a).

Last modified 6.viii.2020