Plant Parasites of Europe

leafminers, galls and fungi

gallers on Alliaria

Dichotomous table for gallers on Alliaria

by Hans Roskam

1a On above-ground parts => 4

1b On roots or root collars => 2

2a On main- or side roots => 3

2b Root collar with rotund succulent, one-chambered swelling, up to 8 mm long. Contains a single larva: Ceutorhynchus assimilis

3a Main- and side roots with conspicuous, spindle- to barrel- shaped succulent swellings. Many cell masses inside with minute spores: Plasmodiophora brassicae

3b Spindle-shaped or nodular swellings of side roots, up to 5 mm long: Meloidogyne hapla

4a Malformations at surface with fungus sori => 10

4b Malformations without fungal sori => 5

5a Malformations on shoot tips or on leaf blades => 7

5b Galls on shoots or petioles => 6

6a Stems or petioles, rarely leaf veins, with spindle-shaped, 10–20 (25) mm long, at first also internal deep green swellings. Containing a single larva: Ceutorhynchus chalybaeus

6b Stem with bulges of variable size, later on blackish; containing many oospores inside the tissue: Hyaloperonospora niessliana

7a Galls caused by aphids or spittlebugs => 8

7b Mite gall. Shoot with irregular development of disfigured leaves. Inducer unidentified – ? gall mite

8a Malformations caused by aphids => 9

8b Malformations caused by spittlebugs. Leaf blade often strongly deflected, at margin ± bent inwards. Leaf blade, especially between the veins, ± bulging; deep green close to the froth-covered nymph: Philaenus spumarius

9a Vegetative and flowering shoot tips clustered, usually with several disfigured together. Leaf blades ± deflected, curled. Flower parts disfigured, ± greened. Fruits sometimes distorted and thickened: Lipaphis alliariae

9b Malformation inconspicuous, usually restricted to single or several terminal leaves: Myzus persicae

10a Sori of fungus expanded, loose covers, consisting of branched conidiophores: Hyaloperonospora niessliana

10b Conidiophores not branched, united into dense, at first glossy, porcelain-like, sometimes bulging swollen sori which release mealy dusting of spores after rupturing: Albugo candida

Last modified 29.iv.2020