Plant Parasites of Europe

leafminers, galls and fungi

gallers on Rubus

Dichotomous table for gallers on Rubus

by Hans Roskam

1a On above-ground parts => 3

1b On roots, on root collar or on basal stem parts => 2

2a Roots, root collar or basal stem parts with irregular proliferations, up to 20 mm long, at first succulent, later on lignifying, ± globular, rough on the surface, without gall chamber. Rubus spp.: Agrobacterium tumefaciens

2b Young roots of R. idaeus with several swellings, 1–2 mm long, approximately urn-shaped, with fungus mycelium interspersed: Mimeuria ulmiphila

2c Small solid swellings, often curved and twisted, at the tips of lateral roots; other parts of roots sometimes thickened; adult eelworms slender and transparent, 1.5–12 mm long; feed on outside of root (so, often are not seen): Longidorus sp. and/ or Xiphidinema sp.

2d Stem base, also roots, with elongated swellings, up to15 mm long, brownish. Pith containing a whitish, black-headed caterpillar. Rubus spp.: Pennisetia hylaeiformis

3a On flowers and fruits => 32

3b On vegetative plant parts => 4

4a On shoot tips or leaves => 8

4b On stem parts => 5

5a Younger or older axis with conspicuous strong swellings => 6

5b Younger, and even lignified shoots with elongate spindle-shaped swelling, which displays a screw-like tunnel around the shoot. R. idaeus, fruticosus: Agrilus cuprescens

5c Salmon pink larvae live under rind. Attacked stem may die back. R. idaeus: Resseliella theobaldi

6a More or less globular, one-sided proliferations or spindle-shaped nodular swellings on the branches => 7

6b Oblong, about 30–80 mm long, and up to 10 mm broad, multi-chambered, with bumpy -tubular swellings, enclosed by glabrous bark. Each chamber containing a single white larva. Rubus spp.: Diastrophus rubi

6c Similar gall. R. idaeus: Aulacidea rubi

7a One-sided protrusions, more or less globular up to 30 mm long, at first succulent, white, later on browned and lignified compact proliferations with tubular surface, usually originating from bud primordia of young lignified stems. Galls sometimes coalescing ridge-like. Rubus spp.: Agrobacterium tumefaciens

= Irregular proliferations, at first short, later on usually extending over several internodes, erupting from bark, pale-green, free from parasites, mainly on two-years old, often additionally swollen shoots of R. idaeus, occasionally also on bramble. Often teratological malformations, predominantly on branches weakened by parasites

7b Rotund to constricted barrel-shaped swelling, mainly one-sided, about 10–20 (50) x 5–7 (20) mm; later woody with rough fissured bark. Inside are many larvae, at first white, later on orange-red. Rubus spp.: Lasioptera rubi

7c Inconspicuous localised swelling. R. fruticosus, idaeus: Agrilus cuprescens

8a Malformations on shoot tips or expanded parts of leaf blade disfigure => 20

8b Localised galls on leaf blades, of ± defined shape => 9

9a Galls almost exclusively on leaf blade parenchyma => 14

9b Galls almost exclusively or mainly on leaf veins, -midrib, -stalk; sometimes only conspicuous by discolouration of leaf blade => 10

10a Venation or axis with bulge-like thickening of various size, soon covered with fungus fructifications => 11

10b Main- or lateral veins of leaflets with swellings 5–7 mm long, 2–3 mm broad, stronger on underside, less protruding on upperside, almost completely filled with larvae and collapsing after their departure. Neighbouring leaf blade parts at first hardly discoloured, after vacation usually yellowish, rarely reddish tinged, occasionally interspersed by a violet-black discoloured venation over a length of 20–30 mm and width of about 12 mm. Larvae conspicuous large, white, sulphur-yellow later on, often greenish translucent. R. idaeus: Buhriella rubicola

11a More or less distinct, facultative yellowish bulges on main venation, on leaflet- and petioles, occasionally also on young shoot stems. In the leaf blades are small rotund patches with spores developing on underside, and sometimes on upper side. Possible gall formation in spring by caeoma-sori of monoecious rust fungi. On. R. arcticus, idaeus, saxatilis => 13

11b Analogous malformations on other Rubus species => 12

12a Aecia with large disc-like warts; mainly developing in often red-margined sori on underside; uredinia rather densely-spiny, teliospores mainly 6-celled, with awl-like tip at apex. Rubus spp.: Phragmidium bulbosum

12b Aecia and uredinia with distantly spiny-warts; telia usually 4-celled, with blunt papilla at apex; developing on often violet-red margined sori. Rubus spp.: Phragmidium violaceum

13a On R. saxatilis: Phragmidium acuminatum

13b On R. arcticus, arcticus x saxatilis, with similar biology, Phragmidium arcticum

14a Galls 2 mm long or less => 16

14b Leaf blade either with expanded rotund pads caused by fungi or with expanded erinea caused by mites on underside => 15

15a Leaf blade with weak, ± yellow, sometimes red-margined, pad-like swellings. Sori either on upper- or underside => 11

15b On underside often with many, locally, slightly expanded rotund depressions with white erinea; on upperside not or only slightly protruding. Hairs ± curved, spirally; erinea sometimes coalescing, but not extending into other organs. Rubus spp.: Eriophyes rubicolens

16a Galls nodule or pustule-shaped, visible on both sides of leaf, caused by animals => 18

16b Galls wart-shaped, one-sided, caused by fungi => 17

17a Warts golden-yellow, many-celled. R. caesius, dumetorum: Synchytrium aureum

17b Warts almost colourless. Galls 1-celled. R. arcticus: Synchytrium myosotidis var. potentillae

18a Galls pustule-shaped, conspicuously shrunken. “Procecidia”, oviposition scars, not true galls => 19

18b Rotund nodules, protruding on both sides, 2 mm across. Exit small, usually on underside, rarely on upperside and then cup-like. With club-shaped or cylindrical hairs inside proliferations, R. arcticus, saxatilis: Aceria silvicola

19a Pustule-shaped egg capsules between leaf dentition. R. fruticosus, idaeus: Arge gracilicornis

19b Egg-shaped “procecidia”, oviposition scars, not true galls, 1.5 mm long, yellow swellings, visible on both sides, often with several together, in the axils of ± curved veins. The emerging larva leaves the gall and lives free on the leaf surface. R. corchorifolius: Unidentified sawfly

20a Malformations mainly of several terminal leaves, caused by aphids => 26

20b Various malformations of single or several terminal leaves by other causers (for witches’ broom-like malformations => 21

21a Malformations sometimes expanded, ± pubescent or glabrous => 22

21b Expanded parts of leaf, shoot- and inflorescence axis, flower peduncle, possibly flower buds, and the green parts of ± opening flowers and even the almost mature, already black-violet coloured mericarps with velvet-like greyish pubescence. Early infected leaves stunted, with curved venation. Hairs cylindrical, acuminate, rigid and longer than the normal ones. Rubus spp.: Epitrimerus gibbosus

22a Galls caused by animals => 24

22b Galls caused by parasitic fungi => 23

23a Leaf blade with yellow, slightly thickened spots, which bear on the upperside spermogonia and on both sides, golden-yellow, primary uredinia arranged in rings. R. caesius, fruticosus, hirtus, nemorosus, plicatus, etc.: Kuehneola uredinis

23b Infected leaves ± disfigured, usually smaller and paler than the healthy ones. In autumn and spring on underside, accompanied by spermogonia, caeoma-sori. R. arcticus, saxatilis: Gymnoconia nitens

23c Similar malformation. R. arcticus, canadensis, chloocladus, leptadenes, saxatilis: Arthuriomyces peckianus

24a Leaflets variously folded upwards and additionally further disfigured => 25

24b Leaflet ± abruptly bent, deflected over the top, close to the infestation site strongly crumpled, dark-green. Rubus spp.: Philaenus spumarius

24c Localised malformation of leaf blade. R. fruticosus: Trioza tripunctata

25a Leaflets folded upwards along ± thickened main veins, undulately curled and often ± discoloured; stunted and sometimes more densely pubescent; several white larvae briefly between folds. Rubus spp.: Dasineura plicatrix

25b Midrib and side veins of first and second order bent in and out. Leaf blade folded, folds scantily pubescent, usually discoloured on underside. Malformations only exceptionally conspicuous, leaf blades ± arched. R. idaeus and many other brambles: Phyllocoptes gracilis

25c Similar, only exceptionally gall-like damage on R. caesius, candicans subsp. thyrsoideus and cultivated relatives: Anthocoptes rubi

25d Vagrant mites on the underside of the leaves. At high densities some discolouration may occur. R. laciniatus: Anthocoptes rubicolens

26a Aphid greenish => 27

26b Populations of green and brownish-red aphids usually present. Siphunculi thin and long, about a third of body length. R. caesius and other brambles: Macrosiphum funestum

27a On raspberry (R. idaeus) and various brambles, R. caesius, fruticosus, etc. => 28

27b On R. saxatilis: Aulacorthum cylactis

28a On brambles => 30

28b On raspberries => 29

29a Leaves weakly arched: Amphorophora idaei

29b Leaves variously crumpled, with several bunched together in relatively compact clusters. Aphis idaei

30a Leaves relatively loosely arched and weakly rolled. Minor stunting of shoot. Malformations only facultative. Aphid yellowish-green to green. Adults larger than 2.5 mm => 31

30b Leaves strongly rolled inwards in spring; aphid also living on green shoots in dense colonies. Aphis ruborum

31a Siphunculi cylindrical and often dark-brown. Antennae slightly shorter than or almost as long as body: Sitobion fragariae

31b Siphunculi slightly swollen, colourless, with thin tip. Antennae longer than body: Amphorophora rubi

= Virus diseases occur widely on Rubus species, especially raspberries, causing mosaic-like discoloured malformations of leaves, as well as curling of many leaves on ± severely stunted shoots

32a On inflorescences or flowers => 33

32b Receptacle thickened. R. idaeus: Unidentified ? tephritid fly

33a Malformations of flowers only => 34

33b All parts of inflorescence with abnormal silvery pubescence. Rubus spp.: Epitrimerus gibbosus

34a Flowers conspicuously greened, leafy or developed further => 36

34b Flowers unopened, variously disfigured => 35

35a Flowers unopened. The calyx, sometimes appearing enlarged, encloses the other, usually smaller, ± disfigured inner flower organs. Many ivory-white to yellowish jumping larvae per bud. Infected flowers soon dropping. Rubus spp.: Contarinia rubicola

35b Corolla stunted, abnormally developed, ± greened. Sex organs reduced; at first greened, later on browned. R. fruticosus: Unidentified thrips

35c Bud swollen, unopened, containing beetle larva. R. ulmifolius incl. vars: Anthonomus rubi

36a Flower organs mostly greened, transformed into small green structures. R. fruticosus: Acalitus essigi

36b Flowers conspicuously and variously disfigured, greened, leafy, sometimes developed further. Rubus spp.: Virus disease

= Cause of the malformations associated with enlargement of calyx in raspberries and brambles is the well-known “Rubus-branching virus”, which may also induce a witches’ broom-like dwarf growth

Last modified 24.viii.2020