Apiognomonia errabunda (Roberge) von Höhnel, 1918

on woody plants

Tilia x europaea, Belgium, prov. Antwerp, Retie, Prinsenpark 29.vi.2018 © Carina Van Steenwinkel

underside of an infected leaf

like in A. veneta the leaf spots develop from the veins, but they are not angular.

same leaf, underside

characteristic also is the black discolouration of the petioles.

leaf spots with hypophyllous brown acervuli.

conidia

gall

usually an asymptomatic endophytic leaf fungus. The anamorph causes in spring drying out of buds, die-off of young shoots, and large leaf spots with hypophyllous acervuli. Conidia 4-6 x 10-13 µm. On beech, where the fungus is very common, it may cause the death of the larvae of Hartigiola annulipes and Mikiola fagi (Wulf).

The teleomorph forms black perithecia with a long neck on fallen leaves and dead branches.

host plants

polyphagous

Chamerion angustifolium; Fagus sylvatica; Fraxinus; Quercus petraea, pyrenaica, robus; Rhus glabra; Salix; Sorbus aria; Tilia cordata, x europaea; Ulmus glabra.

synonyms

Gnomonia errabunda (Roberge) Auerswald, 1869; Discula umbrinella (Berkeley & Broome) Morelet, 1973; Apiognomonia tiliae (Rehm) von Höhnel 1920.

notes

Vainio ao witnessed an outbreak of the fungus on Tilia cordata, causing large-scale defoliation, where it was striking that the petioles had turned blackish brown, while the leaf laminas remained green.

references

Brandenburger (1985a: 61, 64), Butin & Kehr (1999a), Ellis & Ellis (1997a), Kozłowska, Mułenko & Heluta (2015a), Melgarejo Nárdiz, García-Jiménez, Jordá Gutiérrez ao (2010a), Roques, Cleary, Matsiakh & Eschem (2017a), Roskam (2009a), Ruszkiewicz-Michalska (2006a), Sogonov, Castlebury, Rossman ao (2008a), Vainio, Velmala, Salo ao (2017a), Wulf (1990).