Erysiphe syringae Schweinitz, 1834
Mycelium amphigenous, persistent, in dense white spots. Conidia solitary, elliptic, without fibrosin bodies. Cleistothecia, only rarely formed, with 3-8 asci, containing 5-7 spores. Appendages 3-16, equatorial, 1-2 x the diameter; they are stiff, entirely or largely hyaline, with maximally 2, basal septa. At their end they are several times dichotomously branched in three dimensions.
Microsphaera syringae (Schweinitz) Magnus, 1898.
Erysiphe syringae originally is a North-American species, that settled in Europe in the 19th and 20th century. Contrary to the North American population, in Europe cleistothecia are only rarely formed. In 1990 another, closely similar species, syringae-japonicae appeared in Europe from Asia. Braun & Cook state that this second species has almost completely replaced syringae. This stands in sharp contrast with the conclusion by Takamatsu ao that both species co-occur in Europe, and even can occur on the same lilac leaf without any apparent sign of competition.
See under E. syringae-japonicae for the morphological differences between both species.
Beenken & Senn-Irlet (2016a), Braun (1995a), Braun & Cook (2012a), Bresinsky (2016a), Czerniawska, Madej, Adamska ao (2000a), Henricot (2009a), Jage, Klenke & Kummer (2010a), Klenke & Scholler (2014a), Kruse (2019a), Mułenko, Piątek, Wołczańska ao (2010a), Negrean & Anastasiu (2006a), Ruszkiewicz-Michalska (2006a), Ruszkiewicz-Michalska & Michalski (2005a), Sucharzewska, Dynowska, Kubiak ao (2012b), Takamatsu, Shiroya & Seko (2016a), Talgø, Sundheim, Gjærum ao (2010a), Wołczańska & Mułenko (2002a).