Plantparasieten van Europa

bladmineerders, gallen en schimmels

gallers on Picris

Dichotomous table for gallers on Picris

(incl. Helminthotheca)

by Hans Roskam

1a On above-ground parts => 2

1b Roots with nodule-shaped swellings. P. hieracioides: Meloidogyne hapla

2a On vegetative parts => 3

2b On inflorescences => 15

3a On leaves => 9

3b On stems, shoot tips or buds => 4

3c All parts of shoot with white crusty blisters, very variable in size; shoot often distorted; P. echioides, hieracioides: Pustula obtusata

4a Galls on stems, on upper shoot tips or lateral buds => 5

4b Shoot formation in the leaf rosette deformed to a conical, 5 mm long, 9 mm wide gall, with several markedly shortened leaves. Containing one maggot. P. hieracioides: Napomyza lateralis

5a Malformations on stems, sometimes encroaching upon neighbouring buds or lateral shoots => 6

5b Tip of the main- or lateral shoot, also the axillary bud, deformed into rotund or oblong, galls up to 15 mm long, consisting of several strongly pubescent, short imbricated covered leaves. Containing several whitish, non-jumping larvae. Sometimes neighbouring stem parts galled. P. hieracioides: Jaapiella picridis

5c These galls may also contain jumping larvae of Contarinia picridis

6a The gall causers develop outside the galls in pit-like depressions or in erinea => 8

6b The gall causers develop inside the galls => 7

7a Galls of spongy nature; distinct from the outside. Early infected stems often mostly stunted in their longitudinal growth markedly swollen over substantial length, ± bent. Later infection results in ± curved localised swellings of different types, sometimes even including the often irregularly swollen receptacle. P. hieracioides: Ditylenchus dipsaci

7b Longitudinal growth of stem not – or rarely stunted, the outside hardly deformed. In the locally thickened pith are many separated elliptical chambers, about 1–2 mm long each with one larva. P. hieracioides: Unidentified gall wasp

7c Similar galls, but with larger chambers, 2.5–3 mm long each with a white larva, on P. echioides, hieracioides: Phanacis caulicola

8a Especially the basal stem part over various length ± bulging swollen, with one or several depressions containing the gall causer. P. hieracioides: Planchonia arabidis

8b Any part of stem with ± extended, dense, initially white or reddish, later brownish erinea. Sometimes the buds are involved, in which case they are to a large extent stunted. P. hieracioides: Aceria picridis

9a Galls predominantly on leaves, on the mid- and lateral main veins extended in various ways into the leaf blades or malformations exclusively on the petioles => 10

9b Leaves stunted in their development, in various ways curled, with loose, abnormal, pubescence. Between the narrow folds are yellowish, jumping larvae. P. hieracioides & subsp. spinulosa: Contarinia picridis

9c Basal leaves disfigured and curled. P. hieracioides: Protaphis terricola

10a Malformations without conspicuous pubescence => 11

10b Leaves with dense, initially whitish, later reddish, finally brownish erinea of multicellular, twisted hairs often on curved petioles and midribs. Pubescence of varied coverage on the under- or, more often, upperside, of the often curled, or even bulging leaf blade and even protruding onto the neighbouring mostly stunted axillary buds. P. hieracioides: Aceria picridis

11a Swellings spindle-shaped, usually less than 1 cm long, caused by fungi which fruit either inside the gall or on its surface => 13

11b Galls usually more expanded, caused by animal parasites, living inside the galls => 12

12a Galls spongy, usually pale green, sometimes reddened with ± wrinkled surface; in various ways protruding from the petiole or main vein into the ± distorted leaf blade. P. hieracioides: Ditylenchus dipsaci

12b Petiole, along with the basal parts of the main vein, distinctly swollen, predominantly on the underside. Gall glabrous, gradually narrowed towards leaf tip. One larva. P. hieracioides: Phytomyza picridocecis

13a The fruiting bodies of the fungus develop inside the galls => 14

13b Midrib on the leaf underside often with several weak swellings, about 2–5 mm long, sometimes coalescing, often yellow-bordered, occasionally resulting in a distortion of the stems, on the underside soon occupied by brown sori. Pycnidia yellowish and on the upperside. P. hieracioides: Puccinia hieracii

14a alls on the main-, and the lateral leaf veins. Veins particularly swollen on ± irregularly bordered, often yellowish, sometimes reddish discoloured, leaf blade areas on the leaf underside, appearing as a distinctly protruding relief. Spores develop within and close to the vascular bundle. P. hieracioides: Protomyces picridis

14b Small, prominent, closed swellings on the main veins, up to 3 (5) mm long, mostly yellow-bordered, whitish to brownish. P. hieracioides: Entyloma picridis

15a Receptacle transformed into an irregular, multi-chambered woody swelling, nut-size. Sometimes the peduncle of the flower head is inflated. Larval chambers spherical, scattered. Helminthotheca aculeata: Timaspis helminthiae

15b Receptacle transformed into a hard, multilocular mass, 8-‒17 x 14‒20 mm, like the rest of the plant covered with a coarse bristly hair cover. Gall chambers 3‒10. Helminthotheca comosa & subsp. lusitanica: Phanacis comosae

15c On flower heads. Helminthotheca echioides; Picris hieracioides: Tephritis divisa

Laatste bewerking 9.iv.2020