Plant Parasites of Europe

leafminers, galls and fungi

gallers on Scorzonera

Dichotomous table for gallers on Scorzonera

(incl. Arachnospermum, Podospermum)

by Hans Roskam

1a On above-ground parts => 4

1b On roots or root collar => 2

2a Considerable galls on root collar => 3

2b Roots with elongated spindle-shaped swellings, up to 5 mm long, bearing some lateral roots. Coalescing in rows in cases of heavy infestation. S. hispanica: Meloidogyne hapla

2c Lateral roots terminally thickened, ± curved, longitudinal growth stunted, prematurely shrivelled. Whole plant becoming stunted. S. hispanica: Paralongidorus maximus

3a Uniformly succulent, up to walnut size, ± rotund-ovoid proliferation on root collar, sometimes on root- and stem parts close to the surface. “Crown gall disease”. S. hispanica: Agrobacterium tumefaciens

3b Almost globular, glabrous, one-chambered swellings on root collar. Often several variously coalesced, depending upon the number of galls, to form crook-backed structures. One larva per chamber. S. humilis: Aulacidea hieracii

4a On capitula or flowers => 13

4b On stems or leaves => 5

5a Malformations on leaves => 6

5b Stems with conspicuous, crooked swellings at the surface mostly on all sides, 40–60 mm long, about 10 mm thick. Inside the stem are many, clustered rotund galls, each about 2 mm long, and each with one larva. S. austriaca, hispanica, humilis; Podospermum purpureum: Aulacidea scorzonerae

6a On leaf blades or leaf veins => 7

6b Leaf sheaths ± bladder-like swollen and discoloured. Enclosed shoot stunted, with severely stunted development. S. hispanica: cf. Brachycaudus tragopogonis

7a Malformations caused by superficial sori => 11

7b Galls with living animal inducers inside => 8

8a Galls predominantly on the leaf blade or on the secondary veins => 9

8b Midrib on the underside often with several galls, in loose or more clustered constellations appearing pale green, rotund-ovoid, 2–3 mm long, one-chambered. Containing a single larva. S. austriaca, hispanica, humilis; Podospermum purpureum: Aulacidea scorzonerae

9a Galls of definite shape; surface glabrous, usually ± reddened. Midge galls => 10

9b Flat, pale green, ± spongy, rugose galls, especially swollen at the veins and extending over at least 15 mm in length on the leaf blade, ± curved as result of the infestation. S. hispanica: Ditylenchus dipsaci

10a Leaf blade with round pustules, several millimetres wide; bulging on the upperside, yellowish or dirty crimson-red, sometimes surrounded by a reddish discoloured area; the underside lighter, flat. A pale orange-yellow larva. S. austriaca, humilis: Cystiphora scorzonerae

10b Elevated, elongated to spindle-shaped galls, up to 5 mm long, protruding from both leaf surfaces, often yellow or reddish bordered. Often many per leaf blade, the longitudinal stem predominantly situated in a secondary vein and extending on both sides on the leaf blade. Containing a single larva. S. humilis: Unidentified gall midge

11a Malformations with sori of true rust fungi (Uredinales) => 12

11b Oomycetes. Sori oblong-oval, initially closed and porcelain-glossy, white, opening later and with mealy dusting. S. austriaca, hispanica, humilis, parviflora; Podospermum canum, laciniatum; Scorzoneroides autumnalis, helvetica: Pustula obtusata

11c Oomycetes; upperside of the leaves with yellow or brown spots; on the underside a greyish brown fungal down consisting of erect, distally several times branched conidiophores; the final branches ending in an ovoid conidium. S. hispanica, humilis: Novotelnova scorzonerae

12a The primary uredomycelium usually pervades the whole host, whose parts are paler, more lanky or deformed in another way. Spores brown. Podospermum purpureum, roseum; S. austriaca, hirsuta, hispanica, humilis, mollis, papposa: Puccinia scorzonerae

12b Shoot etiolated by the expanded aecial mycelium. Leaves in case of heavy, infection, usually one-sided, conspicuously curved or even twisted. Aecia cup-shaped, later opening with frayed border, widely dispersed over leaves, stems and involucres; yellowish. S. austriaca, hispanica, humilis; Podospermum purpureum, roseum: Puccinia jackyana

13a Malformations induced by insects => 14

13b Diseased capitula already stunted early in development, shortened, initially turgid. Flowers soon completely destroyed and replaced by a black-violet, sparsely dusting spore mass. Podospermum canum, puurpurum, roseum; S. aristata, calyculata, hispanica, humilis, mollis: Microbotryum scorzonerae

14a Receptacle of the unopened flower head ± egg-shaped, swollen. In case of one-sided infestation ± curved. Usually containing one larva. Podospermum purpureum; S. parviflora; Scorzoneroides autumnalis: Trupanea stellata

14b Capitula conspicuously swollen, rotund to elongated ovoid. Galls in the shortened and broadened fruits. Wall thick and woody. Pappus shortened, with withered corolla mounted on the gall. Often many galls per flower head. One yellowish-white larva per gall. Podospermum purpureum, roseum; Scorzonera humilis, parviflora: Aulacidea abdominalis

14c Base of flower head is usually enlarged; the conglomerate of galls lignified, hard. Larval chamber is round or slightly ovate, developing in seeds which are slightly swollen. Pdospermum purpureum, roseum; Scorzonera humilis, parviflora: Aulacidea abdominalis

14d A stem swelling-like gall, usually located under the flower head, sometimes in the lower part of the stem; spindle-like or cylindrical stem enlargement, 30‒60 mm long, 10 mm in diameter; the surface with longitudinal ribs, as on the stem, sometimes the ribs are waved and distance between them is larger, depending on the diameter of the gall. In a longitudinal dissection, single 2 mm long larval cells are visible which are located near one another. The number of larval cells is larger towards the periphery of the gall. The stem above the gall is shortened and the flower head terminates its development. S. austriaca, hispanica, humilis; Podospermum purpureum: Aulacidea scorzonerae

14e Galls induced in achenes. Podospermum laciniatum: Aulacidea laurae

Last modified 28.iv.2020