Plant Parasites of Europe

leafminers, galls and fungi

gallers on Aster

Dichotomous table for gallers on Aster

by Hans Roskam

incl. Bellidiastrum, Chrysocoma, Galetella, Symphiotrichum, Tripolium

“Asters” are here incidentally without further designation indicated as hosts for many parasites, especially Meloidogyne-species. It is often not clear which Aster-species, Callistephus [= Aster] chinensis or even cultivated Chrysanthemum-species have been meant by many authors

1a On capitula => 21

1b On vegetative parts => 2

2a Galls less than 1 mm long or with fruiting fungi on the surface => 15

2b Other kinds of malformations caused by animals (or bacteria) => 3

3a Malformations mainly on leaves => 8

3b Galls at the top of main- and lateral shoots or on stems => 4

4a Terminally on plants the growth of which is not stunted => 6

4b Swellings of lower stem parts => 5

5a Stem with considerable, one-sided, ± blistered, smooth-walled, unilocular swelling, Larva without head capsule or legs. Bellidiastrum michelii: Tephritis arnicae

5b Spongy, pale, often massive stem galls with rugose surface. “Aster”: Ditylenchus dipsaci

5c Stem base, still above the underground root collar, swollen; in other areas one-sided, oval, about 10–12 mm long, 3 mm wide; almost on all sides of the thin stems. A yellow caterpillar up to 10 mm with a yellow-brown head capsule. Galetella linosyris: Caulastrocecis furfurella

= Root cankers, caused by Agrobacterium tumefaciens, and “leafy galls” of Rhodococcus fascians have been reported

6a Malformations without conspicuous swellings of the stem => 7

6b Plant growth stunted in longitudinal direction, shoot tip swollen, curved and reddened. One caterpillar. Galetella linosyris, Tripolium pannonicum subsp. tripolium: Eucosma aspidiscana

6c Very conspicuous swelling of twig, containing one caterpillar. Galetella sedifolia: Caulastrocecis gypsella

7a Shoot stem shortened. Abnormal twig- and leaf development on long- or short shoots. Galetella linosyris: Aceria linosyrina

7b On the stunted shoots a rotund gall encased by several leaves, up to 10 mm long, greenish. Larvae between the inner leaves. A. alpinus: Rhopalomyia astericola

8a Leaf blade rolled, folded or curled => 11

8b Leaves with local, ± constant shaped, galls => 9

9a Galls glabrous => 10

9b Whitish pubescent, rotund, spongy, uni- or multilocular galls, up to 16 mm long, yellowish, often many on ± stunted plants, mainly close to basal leaves, more rarely on stem leaves or even on the scales of the capitula. A. alpinus: Unidentified gall midge

10a Leaf blade with greenish-yellow galls, 3–5 mm long, bulging on the underside, about 1.5 mm thick, ± spindle-shaped; often spreading from midrib and occupying or even surmounting the whole leaf blade; sometimes several per leaf, occasionally coalescing. One dark orange-yellow larva per gall. On Galatella linosyris; Tripolium pannonicum: Dasineura linosyridis

10b Cylindrical, up to 20 mm long, 5 mm wide, very thick-walled, tough, multilocular, tubercular gall on leaf base, including the midrib. The upper leaf part folded along the midrib. Tripolium pannonicum: Inducer unidentified – ? gall wasp

11a Leaf blade curved and curled by aphids or cercopids => 14

11b Leaf blade folded or rolled; midge- or mite galls => 12

12a Leaf margin rolled => 13

12b Leaf blade folded downwards, ± bleached. Galatella linosyris: Unidentified gall midge

13a Leaf margin upwardly curved or folded, thickened and bleached. Larvae on upper side. A. alpinus: Unidentified gall midge

13b Leaf blade with loose, weakly thickened leaf margin roll without abnormal pubescence. Bellidiastrum michelii: Aceria opistholia

14a Leaf blade at the margins downwardly curved or rolled, ± strongly curled. Sometimes several leaves densely bunched at the compressed shoot tips. Aphids on the underside. A. amellus and cultivated forms, Bellidiastrum michelii, Tripolium: Brachycaudus helichrysi

14b Leaves, depending on their condition, differently ± strongly curved downwards and curled. Tissue close to the froth-covered nymph dark green. Sometimes several leaves converging spoon- or clump-like on compressed, ± curved stems. A. amellus, Symphiotrichum novae-angliae, novi-belgii including the cultivated forms, S. lanceolatum, Tripolium, etc.: Philaenus spumarius

15a Fungus, infected area larger than 1 mm => 16

15b Many golden-yellow warts, hardly 1 mm long, mainly on the underside of basal leaves. Bellidiastrum michelii: Synchytrium aureum

16a Minor swellings, occupied by brown-black telia => 19

16b Sporangia containing aecia => 17

17a On Bellidiastrum michelii, Tripolium => 18

17b On Galatella linosyris. Sporangia mainly on the underside of the leaves, yellowish, hardly swollen, sometimes bulging the leaf out laterally; also indistinctly swollen callus on the stems about 5–7 mm long: Puccinia linosyridis-caricis

18a On Tripolium. Sori on leaves and stem hardly cecidogenic. Visible malformations only reported laterally on the base of the capitula slightly swollen, ± bent flower head buds. Puccinia extensicola

18b On A. bellidiastrum, hardly cecidogenic aecia: Puccinia firma

19a On A. alpinus, Bellidiastrum michelii => 20

19b On other asters. Sori on the leaf veins or stem parts rotund-oval to spindle-shaped, on sometimes slightly swollen pads. A. amellus, Galatella linosyris, Tripolium, etc.: Puccinia cnici-oleracei

20a Similar sori on A. alpinus: Puccinia asteris-alpini

20b Sori usually in converging, callus-like groups on curved petioles and leaf veins; occasionally on rotund, usually violet-red bordered pads on the leaf undersides. Bellidiastrum michelii: Puccinia bellidiastri

21a Capitula deformed. Receptacle swollen, all- or one-sided. Larvae in receptacle, cylindrically shaped, with black mandibles => 22

21b Capitula hardly swollen. Larvae without conspicuous mouth parts, between flowers. Galatella linosyris: Dasineura procera

= In capitula of Bellidiastrum michelii midge larvae of an undescribed Dasineura have been mentioned.

21c Florets forming a compact rosette of green leaves (phyllanthy); contains mites with four pairs of legs. Symphyotrichum novi-belgii: Phytonemus pallidus

22a Galls preferentially when unilaterally affected ± bent downwards; marginal flowers partially not developed. Tripolium: Campiglossa plantaginis

22b Similar malformations Tripolium: Trupanea stellata

22c In Germany, J. Haase collected inflorescences of Tripolium with many widely extending capitula, of which the flowers were largely reduced and deformed. Cause unknown; similar malformations also known from other Asteraceae, especially Liguliflorae and Cynareae. Might be caused by viruses.

Last modified 30.iii.2020