Plant Parasites of Europe

leafminers, galls and fungi

gallers on Dipsacus

Dichotomous table for gallers on Dipsacus

(incl. Virga)

by Hans Roskam

1a On above-ground parts => 2

1b Side roots with nodular swellings. D. sativus: Meloidogyne hapla

2a On vegetative parts => 4

2b On capitula => 3

3a Infected capitula often strange-looking. Several petals enlarged, ± disfigured, discoloured. Anthers and ovaries largely aborted. Loose down of branched conidiophores on petals of usually completely diseased capitula. D. fullonum, laciniatus, pilosus: Peronospora violacea

3b Many parts of capitula disfigured; diseased tissue hypertrophied, soon browning and dying. Infected fruits reduced, twice as thick as normal ones; pappus sessile, swollen. Seed coat thickened, rounded. D. fullonum, sativus: Ditylenchus dipsaci

4a Malformations on rosette leaves => 6

4b Malformations of higher situated parts => 5

5a Leaf blades of larger stem leaves, including tip, mainly deflected on one side; strongly curled and deep green close to the froth-covered nymph. Dipsacus spp.: Philaenus spumarius

5b Undescribed gall-like malformations caused by aphids. D. sativus: cf. Aulacorthum solani

= On D. laciniatus and D. fullonum the gall mite Leipothrix dipsacivagus has been described causing rusting and wrinkles on the longitudinal folds of leaves

6a Usually several inner leaves of spring rosettes infected, more erect; leaf blades narrowed, slightly thickened and ± brittle; usually to a large extent the infected parts alongside the midrib are pale green, bulging upwards over the normally coloured marginal areas, covered on underside by a dirty pale grey down of branched conidiophores. D. fullonum, laciniatus, pilosus: Peronospora dipsaci

6b Rosette leaves in spring stunted, shortened, spongy and swollen, especially at base, pale, sometimes clustered, cabbage-like. D. sativus: Ditylenchus dipsaci

6b Leaves with small gregarious pustules, less than 0.5 mm across. D. fullonum: Synchytrium succisae

Last modified 25.v.2020