Plant Parasites of Europe

leafminers, galls and fungi

gallers on genus Diplotaxis

Dichotomous table for gallers on Diplotaxis

by Hans Roskam

1a On parts above ground => 3

1b On roots or root collar => 2

2a Roots with conspicuous, mostly, spindle-shaped to cylindrical, fleshy swellings. Inside the galls are cells containing spore masses. D. erucoides: Plasmodiophora brassicae

2b Root collar with one to several rotund galls, up to 5 mm long, with a curved larva inside. D. muralis: Ceutorhynchus assimilis

3a On flowers and siliques => 7

3b On stems or leaves => 4

4a Localised or extensive deformations caused by animal gall causers => 5

4b Leaf blade on the underside with flat, rotund cushions. Leaf axial parts or stem with ± expanded, sometimes distorted bulge-like swellings, initially covered with closed dense white sori, at first-glossy, porcelain-like, with mealy dusting after opening. D. muralis, tenuifolia: Albugo candida

5a Deformations caused by aphids => 6

5b About 10–15 mm long, spindle-shaped, partially deep green swellings on the midribs or stems. Containing a single larva. D. muralis, tenuifolia: Ceutorhynchus chalybaeus

6a oung lateral shoots distinctly stunted; occupied by conspicuously reduced and deformed, more densely situated, leaves. D. tenuifolia: Lipaphis rossi

6b Leaf blades folded locally, leaf margins rolled. D. muralis, tenuifolia: Brevicoryne brassicae

7a Malformations caused by gall midges => 9

8b Other causers => 8

8a Greening of flowers. D. muralis, tenuifolia: Brevicoryne brassicae

8b Ovaries in one or several flowers of an inflorescence deformed, narrowed and elongated; anthers shrivelled, corolla stunted; ± greened; calyx partially conspicuously enlarged. On many parts bulge-like white fungal sori occur. D. erucoides, muralis, tenuifolia, virgata: Albugo candida

9a Malformations of flowers or flower parts => 10

9b Swelling of silique => 11

10a Single or several buds per inflorescence distinctly swollen, unopened. Similar galls; calyx and corolla sometimes less swollen. larva usually lighter yellow, jumping. D. muralis, tenuifolia: Contarinia nasturtii

10b Swollen flower buds. White, non-jumping larvae. D. muralis, D. catholica, D. erucoides: Gephyraulus diplotaxis

10c Swollen siliques, inside only one larva. Pupation in gall. Two generations. D. tenuifolia: Asphondylia stefanii

11a Spindle-shaped swelling of silique, often silique bent at right angle. D. tenuifolia: Dasineura napi

11b Siliques swollen, containing a single orange midge larva. D. tenuifolia:
Asphondylia stefanii

11b Siliques turgid, deformed and curved. D. tenuifolia: Dasineura napi

Last modified 17.xi.2023