Plant Parasites of Europe

leafminers, galls and fungi

gallers on Hornungia

Dichotomous table for gallers on Hornungia

by Hans Roskam

1a On green plant parts => 2

1b On root collar, a one-sided rotund one-chambered swelling, up to 5 mm long. Containing a single white larva. H. alpina: cf. Ceutorhynchus assimilis

2a On leaves or stems => 3

2b lowers greened. H. alpina: Aceria drabae

3a More or less spindle-shaped galls on shoot axis => 4

3b Wart-shaped, multi-cellular, often variously coalesced galls on stems and flowers. H. alpina: Synchytrium infestans

3c Occasional infestation. H. petraea: Peronospora hornungiae

4a Vegetative part of stem spindle-shaped swollen. H. alpina: Unidentified snout beetle

4b Stem predominately swollen over variable length in inflorescence region and bearing white, later on vitreous, dusting of sori. H. alpina & subsp. auerswaldii, petraea: Albugo candida

4b Stem and also axis of inflorescence usually with expanded, conspicuous, often distorted swellings, soon covered with a down of branched conidiophores. Flowers of diseased inflorescences severely stunted. Leaves of axillary shoots if infected early, ± spoon-like arched, thickened, brittle, pale green; with a dense down of conidiophores on underside. H. alpina & subsp. auerswaldii, petraea: Hyaloperonospora parasitica

Last modified 5.vii.2020