Plant Parasites of Europe

leafminers, galls and fungi

gallers on Juniperus

Dichotomous table for gallers on Juniperus

by Hans Roskam

1a On above-ground parts => 2

1b Roots with nodular swellings. J. communis: Meloidogyne sp.

2a On fruits => 28

2b On vegetative plant parts => 3

3a On terminal shoots, shoot tips or only on leaves => 13

3b On lower axial parts of shoot => 4

4a Shoot axis with tuberose- or elongated swellings of various length => 5

4b Bark of younger shoots with, rimmed depressions, up to 2 mm long, containing inducer. J. communis: Carulaspis juniperi

5a Elongate galls without larval cavities, at maturity with fungal structures at their surface => 9

5b Similar galls, but with tunnels caused by of lepidopteran larvae feeding => 6

6a Caterpillar white to reddish => 7

6b Caterpillar pale brown, head black, neck- and anal scale brown. J. communis: Chionodes electella

7a Caterpillar usually uniform white => 8

7b Caterpillar dirty white, often reddish tinged; head and neck scale brown. J. communis: Cydia duplicana

8 Caterpillar biannual, ivory white. J. communis: Synanthedon cephiformis

8b Caterpillar annual, whitish. J. communis: Synanthedon spuleri

8c The so-called “tuberculate disease” in twigs of Mediterranean J. communis, phoenicea as well as on Cupressus sempervirens has been attributed to: Ceratostoma juniperinum

9a Spindle-shaped to elongated cylindrical swellings of twigs and branches. Telia partially thick-, partially thin-walled, dark to pale, on ± long stalks; sori united under humid conditions into gelatinous swollen columns, tongues or pads; uredinia absent. In spring, on J. communis and relatives => 11

9b Similar galls on J. sabina and relatives. Sori of telia cornicular, thick, usually higher than wide. Telia oval to short, spindle-shaped => 10

10a Sori brown-red to chestnut brown, at first pad-shaped, then developing yellow-brown blunt-conical lobes. Galls with perennial mycelium, spindle-shaped, 6–8 cm long. Juniperus spp.: Gymnosporangium confusum

10b Sori black-brown to black. Galls with perennial mycelium, when mature about 10 (12) cm long and 3–4 cm thick. Juniperus spp.: Gymnosporangium sabinae

11a Sori flat cushion-shaped, much broader than high, swelling to a mussel-shaped body. Telia oval or short spindle-shaped, hardly twice as long as broad, partially thick-, partially thin-walled => 12

11b Sori cylindrical, band- or tongue-shaped, up to 5 mm long, 2 mm thick, orange-coloured; swelling to a pale yellow compact jelly-like body when wet, clustered on slender spindle-shaped swelling of stem parts sometimes bent, perennial. Telia oblong-spindle-shaped. Juniperus spp.: Gymnosporangium clavariiforme

12a Dry sori forming flat brown, 1–2 mm high, up to 5 mm broad and 20 mm long pads, which swell to orange-coloured, mussel- or cup-like extending jelly bodies if humid. Swellings often little pronounced; mycelium soon withering. Juniperus spp.: Gymnosporangium tremelloides

12b Witches’ broom on J. oxycedrus, microcarpa: Gymnosporangium gracile

12c Sori usually smaller, developing into yellow-red discoloured jelly bodies; distinguished by its smaller spores. Galls usually on thinner twigs as weak spindle-shaped swellings. Sori also on needles: Gymnosporangium cornutum

= In addition, a rust gall, caused by Gymnosporangium asiaticum has been recorded on introduced J. chinensis

13a On shoot tips => 17

13b On leaves => 14

14a Bulging or tongue-shaped malformations on terminal part of needles, caused by fungi => 15

14b Basal part of needle bulging, swollen. Internodia ± shortened. J. communis, etc.: Trisetacus juniperinus

15a Spores brown, predominantly 2-celled, in gall-like sori; swellings ± compact, slightly bulging => 16

15b Spores black, 1-celled in 3–6 mm long severely blister-like arched dusty sori. J. communis: Lepidoderma carestianum

16a Two-year to perennial needles on upperside with small, slightly arched, lacerate, cinnamon- to black-brown sori, also containing, apart from 1-celled ± globular brown uredinia, 2-celled teliospores, ± egg-shaped, slightly constricted in the middle. J. communis: Gymnosporangium gaeumannii

16b Similar, usually only pinhead size jelly bulges, macroscopically hardly different from previous fungus, containing only 2-celled teliospores. J. communis: Gymnosporangium cornutum and/ or Gymnosporangium tremelloides

17a Galls on tips of shoots => 19

17b Malformation of many leaves terminally on stunted shoots => 18

18a Dense accumulation of almost imbricated covered needles at top of young stunted shoots. J. communis: Cause unknown – ? aphid

Many needles accumulated at the end of a shoot; swollen at base, bulging. J. communis, chinensis: Trisetacus juniperinus

19a More or less bud-like galls caused by gall midges. On J. communis => 21

19b Similar galls on J. sabina => 20

19c Pear-shaped galls with blunt apex on J. oxycedrus, navicularis 10–12 mm long and 8–10 mm wide at base formed by an atrophied brownish inner whorl of needles enclosing a larval chamber and an outer whorl of very broad thickened needles, fused at base and slightly shortened. Containing a single larva: Oligotrophus valerii

20a Pyramid-shaped gall, up to 13 mm long and 5 mm broad, at base gradually narrowing, consisting of 3–5 (7) distinctly enlarged pairs of acuminate leaves; back of leaves rounded and weakly carinate. J. sabina, phoenicea: Etsuhoa sabinae

20b Gall consisting of several pairs of leaves, up to 5 mm long, rotund, strongly shouldered at base. Leaves thickened, their back with deep furrow. Containing a single larva. Unidentified gall midge

21a Gall is composed of two or more whorls of needles => 22

21b The small gall, up to 3 mm long, is oblong-egg-shaped and consists of only one whorl ± distinctly shortened, broadened, mutually covering leaves. Containing a single orange-coloured larva. J. communis: Oligotrophus gemmarum

22a Galls always composed of only two whorls => 25

22b Galls composed of (2) 3–4 whorls => 23

23a Galls larger than 5 mm => 24

23b Gall consists of 2–4 whorls, egg-shaped to conical, small, occasionally up to 4 mm long; outer needles scale-like broadened, composing a closed gall. Galls sometimes also in the male inflorescences. Unidentified gall midge

24a Gall composed of 3–4 whorls, up to 10 mm long, oblong, ± acuminate, terminally on main- and lateral shoots. Needles of the outer whorl ± shortened and distinctly broadened, those of the second whorl slightly longer, but narrower, the inner becoming narrower and smaller, enclosing the central larval chamber. At maturity of the gall, the needle tips are usually outwardly deflected. Containing an orange-coloured larva. J. communis: Oligotrophus sp.

24b Similar galls, containing single red larvae when mature. Unidentified gall midge

25a Needles of the outer whorl ± open or outer whorl spreading at least at maturity of gall => 26

25b Gall up to 12 mm long; ± slender conical, acuminate. Needles of the outer whorl only broadened in the basal half the upper half narrowed, enclosing completely the inner whorl of shorter, narrower needles. Containing a single orange-coloured larva. J. communis: Oligotrophus panteli

26a Galls at most 6 mm long => 27

26b Up to 12 mm long, oblong, not acuminate gall. Needles of the outer whorl broadened and thickened over their whole length. Needles of the inner whorl narrow, adpressed. Leaves of the outer whorl spreading distally at maturity. Containing a single orange-coloured larva. J. communis: Oligotrophus juniperinus

27a Gall often acuminate, up to 5 (6) mm long, ± discoloured. Needles of the ± open outer whorl mainly broadened at base, terminally distinctly narrowed, sometimes deflected outwardly, shorter than inner ones, composed of a closed whorl of converging narrow leaves. containing a red larva. J. communis: Oligotrophus schmidti

27b Open, up to 5 mm long, rarely larger gall, in which the distinctly broadened leaves of the ± spreading outer whorl are as long as, or shorter than the closed inner whorl, usually blunt- to acute-conical gall body. Containing a single red larva. Oligotrophus sp.

28a Fruit slightly swollen, slightly stunted; flesh hypertrophied, carpels incompletely fused, composing at the top a three–rayed opening. Seeds usually sterile, visible under the slits. J. communis: Trisetacus quadrisetus

28b Fruit with grooved, rimmed depressions. J. communis: Carulaspis juniperi

Last modified 5.v.2020