Plant Parasites of Europe

leafminers, galls and fungi

gallers on Scrophularia

Dichotomous table for gallers on Scrophularia

by Hans Roskam

1a On inflorescences, flowers and fruits => 10

1b On vegetative organs => 2

2a Localised or extensive malformations mainly on leaves or terminally on higher placed parts of shoot => 5

2b Galls on lower or middle stem parts => 3

3a The causers develop inside the galls => 4

3b Stem with bulging swellings of different length, mainly close to ground, bearing on their surface several rimmed depressions containing a nymph. Scrophularia spp.: Planchonia arabidis

4a Young shoots close to ground, or also on higher placed parts of side shoots, completely or locally severely stunted, spongy, often conspicuously curved with wrinkled surface. Occasionally encroaching onto petioles and basal parts of ± disfigured leaf blades. S. nodosa: Ditylenchus dipsaci

4b Stem with localised nodular or spindle-shaped, variously distorted swelling. Gall wall browned inside. Leaves clustered at infestation; complete plant ± disfigured. S. nodosa: Cause unknown – ? insect

5a Wart-shaped galls or expanded, variable malformations caused by fungi => 8

5b Malformations caused by animals => 6

6a Single or many leaves with bladder-like swellings or curls => 7

6b Leaves clustered, rosette-like; leaf blades thickened. S. umbrosa: Unidentified gall midge

7a Leaves stunted, with bulging reddened swellings. S. nodosa: Unidentified ? thrips

7b Leaf blade curled, strongly bent downwards at infestation, there deep green. Internodes ± stunted if infected, resulting in clustered ± curled leaves. S. umbrosa, nodosa: Philaenus spumarius

8a Malformations of undefined extent => 9

8b Galls wart-shaped, multi-cellular, less than 1 mm across, ± golden-yellow. Usually many on underside of basal leaves; also on petioles and young stems; sometimes joined into crusts or ridges. S. nodosa, umbrosa: Synchytrium aureum

9a Leaf blades on hardly swollen, rotund to widely expanded spots with usually yellow or reddish bordered sori of fungus. On main veins, petioles and stems developing sori more strongly thickened; bulges of variable size; diseased leaves and stems often severely distorted. At first with spermogonia and aecia, soon also bearing telia. Scrophularia spp.: Uromyces scrophulariae

9b Completely diseased young shoots at first develop faster and firmer than healthy ones, remaining lanky and bear pale-green leaves with narrowed, slightly thickened leaf blades, which are soon covered with a down of branched conidiophores on underside. S. nodosa, scopolii, umbrosa: Peronospora sordida

10a Flower or inflorescence galls => 11

10b Fruit slightly swollen and disfigured only if infected in right phase. Usually containing a single larva. Scrophularia spp.: Rhinusa tetra

11a Flower galls => 12

11b Inflorescence curved; terminal leaves curled. Flower buds contain several at first white, later on orange coloured larvae. S. nodosa, scorodonia: Macrolabis scrophulariae

12a Flowers strongly swollen, unopened. Calyx slightly changed; corolla thickened, especially the tube; stamens with thickened filaments transformed into irregular, leaf-like organs. Ovaries swollen; inner wall covered with dirty white mycelium. Containing a single yolk-yellow larva. S. canina, decipiens, grossheimii, nodosa, umbrosa: Asphondylia scrophulariae

12b Flowers swollen, globular, usually unopened. Stamens and pistil enlarged. Larvae live between flower parts, white to lemon-yellow, jumping. S. auriculata, canina, nodosa, schousboei, umbrosa: Contarinia scrophulariae

Last modified 28.iv.2020