Peronospora radii de Bary, 1864

on Asteraceae, Anthemideae

Tripleurospermum maritimum, Belgium, prov. Limburg, Herk-de-Stad, Schulensbroek © Carina Van Steenwinkel: the ligules stand unusually erect

the disc florets bear no down but are disfigured nonetheless

ligules with dark grey down

the tem is remarkably short and thick

terminal branches

the conidiophores arise from a basal disk-shaped organ

young conidia

mature conidia

Tripleurospermum maritimum, Belgium, prov. Limburg, Bree, de Luysen © Carina Van Steenwinkel<

the conidiophores are standing on a remarkable “attachment disc”

germinating conidium

gall

downy mildew on the leaves, but mainly on the disfigured flower heads, in particular the ligulate flowers. A down of erect, apically repeatedly dichotomously branching conidiophores produces a greyish-violet mass of conidia.

host plants

Asteraceae, narrowly oligophagous

Achillea ptarmica; Anthemis arvensis, cotula, ruthenica; Argyranthemum frutescens; Coleostephus myconis; Cota austrica; Glebionis coronaria, segetum; Leucanthemum vulgare; Matricaria chamomilla, discoidea; Tripleurospermum inodorum, maritimum

synonyms

Peronospora danica Gäumann, 1923.

references

Belbahri, Calmin, Pawlowski & Lefort (2005a), Ben-Ze’ev, Kenneth & Bonde (1987a), Brandenburger (1985a), Buhr (1964b), Chater, Woods, Stringer, ao (2020a), Constantinescu (1989), Doppelbaur, Huber & Poelt (1965a), Ellis & Ellis (1997a), García-Blázquez, Constantinescu, Tellería & Martín (2007a), Göker, García-Blázquez, Voglmayr ao (2009a), Gustavsson (1991a), Jage, Klenke, Kruse ao (2017a), Klenke & Scholler (2015a), Kozłowska, Mułenko & Heluta (2015a), Kruse (2019a), Kruse, Thiel, Beenken ao (2018d), Müller & Kokeš (2008a), Roskam (2009a, 2019a), Rossman (2004a), Săvulescu (1948a), Thines & Choi (2016a), Tomasi (2014a), Voglmayr (2003a).