Peronospora arborescens (Berkeley) de Bary, 1863

on Papaver

Peronospora arborescens on Papaver somniferum

Papaver somniferum, Hungary, Levél © László Érsek

Peronospora arborescens on Papaver somniferum

malformed leaves

Peronospora arborescens on Papaver somniferum

underside of an infected leaf

Peronospora arborescens on Papaver somniferum

The down is exceptionally deeply coloured here.

Peronospora arborescens: galls on Papaver rhoeas

Papaver rhoeas, Belgium, prov. Namur, Couvin, Aublain © Sébastien Carbonnelle

gall

upper side of the leaves with small, venation-delimited, initially yellow, ultimately red to brown, spots. Their underside with a felty down, consisting of erect, 360-600 µm high conidiophores that apically several times are dichotomously branching, each branch ending in a conidium

hostplants

Papaveraceae, nauw monophagous

Papaver rhoeas.

synonyms

See the discussion under Peronospora minor.

primary and secondary infections.

In situations where poppies are cultivated for a series of years it is possible to distinguish between primary and secondary infections. A primary infection happens when plants already in the seedling stage are infected by oospores that have passed the winter in the soil. The infection then is systemic, the plans are stunted and large-scale malformations occur (pictures above). Secondary infections are caused by airborne conidia; these infections cause localised lesions on the leaves (photos below)

Peronospora arborescens on Papaver somniferum, secondary infection

Papaver somniferum, Hungary, Levél © László Érsek

Peronospora arborescens on Papaver somniferum, secondary infection

old lesions, upper side

Peronospora arborescens on Papaver somniferum, secondary infection

underside

notes

considered by Mułenko ao (2010a) a neophyte; first observation in Poland was in 1866.

references

Belbahri, Calmin, Pawlowski & Lefort (2005a), Brandenburger (1985a), Buhr (19645a), Choi, Constantinescu & Shin (2007a), Cunnington (2008a), Doppelbaur, Huber & Poelt (1965a), García-Blázquez, Constantinescu, Tellería & Martín (2007a), Göker, García-Blázquez, Voglmayr ao (2009a), Gustavsson (1991a), Klenke & Scholler (2015a), Kozłowska, Mułenko & Heluta (2015a), Losa España (1944a), Mułenko, Piątek, Wołczańska ao (2010a), Kruse (2014a), Kruse & Jage (2014a), Müller (2015a), Müller & Kokeš (2008a), Negrean, Constantinescu & Denchev (2004a), Özaslan, Hüseyin & Erdogdu (2014a), Redfern & Shirley (2011a), Săvulescu (1948a), Thines, Telle, Ploch & Runge (2009b), Tomasi (2014a), Voglmayr (2003a), Voglmayr, Montes-Borrego & Landa (2014a).

mod 21.iii.2018