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