Plant Parasites of Europe

leafminers, galls and fungi

gallers on Alyssum

Dichotomous table for gallers on Alyssum

(incl. Aurinia, Ptilotrichum)

by Hans Roskam

1a On parts above ground => 4

1b On roots or root collar => 2

2a On roots => 3

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

3a Galls ± rotund, up to 5 mm long, succulent, many on side roots. A. montanum: Meloidogyne hapla

3b Main- and side roots with conspicuous, spindle- to barrel- shaped, succulent swellings. Inside many cell masses with minute spores. Alyssum spp.: Plasmodiophora brassicae

4a Malformations with white pads caused by fungi => 10

4b Malformations caused by animals => 5

5a On inflorescences or flowers => 9

5b On vegetative parts => 6

6a Stem with localised swellings. Galls with midge larvae inside or containing causers in rimmed depressions => 7

6b Young shoots ± stunted and arched; leaves clustered; often nest-like deflected; close to the froth-covered nymph ± deep green discoloured. Alyssum spp.: Philaenus spumarius

7a Larvae are inside gall => 8

7b Stem bulging over variable length, variously distorted, outside with single or several rimmed depressions containing a scale insect. Alyssum spp.: Planchonia arabidis

8a Terminal part of stem stunted, transformed into a 10‒15 mm long, 6–8 mm wide gall. Leaves densely clustered, swollen at base. A. alyssoides, gmelinii, murale: Janetiella fallax

8b Shoot with up to 4 mm long, about pea-size, spindle-shaped swellings. A large chamber contains several red larvae. A. alyssoides, montanum: Dasineura alyssi

9a Inflorescence disfigured over a substantial part. Flowers greened and/or leafy; abnormally white pubescent. A. alyssoides, hirsutum, Ptilotrichum halimifolium, tortuosum: Aceria drabae

9b Flowers swollen, unopened. Containing a single larva. Aurinia saxatilis: Unidentified gall midge

= The gall midge Dasineura auriniae is described from swollen flower buds of Aurinia petraea.

10a Rotund to oval, several mm long, at first closed, glossy, porcelain-like ± swollen bulges on stems and leaves. Later on with mealy dusting of closely arranged conidiophores. Alyssum spp.: Albugo candida

10b Leaves often distorted, usually with several, solitary or clustered, little wart- to bulge-like swellings on upper side, more rarely on underside. In the cavities branched conidiophores make narrow erinea. Sometimes expanded covers on bulging midribs or variously disfigured flowering or non-flowering shoots. Alyssoides utriculata; Aurinia saxatilis: Hyaloperonospora galligena

Last modified 30.iv.2020