Plant Parasites of Europe

leafminers, galls and fungi

gallers on Abies

Dichotomous table for gallers on Abies

by Hans Roskam

1a On needles, on young, ± stunted shoots or on developing buds => 4

1b On lignified younger or older stem parts => 2

1c arvae develop gregariously (1−8 together) inside young seeds in cones. A. alba, cephalonica, nordmaniana: Resseliella piceae

= Fresh resin masses of damaged shoots of A. alba rarely may contain gall midge larvae of Resseliella crassa and/or R. resinophaga

2a Older lateral shoots, sometimes also the stems, occupied by conspicuous witches’ brooms or mistletoes => 3

2b Axial parts of younger shoots often severely stunted, with ± club-like to nodule-shaped, also forked and twisted swellings, or older stem parts with irregularly expanded, ± bulging proliferations of bark. Sometimes also the buds are transformed into globular or egg-shaped galls. Abies spp.: Dreyfusia piceae

2c A very similar aphid may occur on young plants of A. alba, nordmanniana: Dreyfusia merkeri

3a Witches’ brooms with erect main shoots, abundantly branched, developing from globular to barrel-shaped, often conspicuous thickenings. Needles distinctly shortened, thickened, yellow-green, directed to all sides, falling in autumn. A. alba and several foreign species. Melampsorella caryophyllacearum

= In Melampsorella galls and other cancer-like malformations on conifers the tortricid moth Cydia duplicana, as well as the gelechiid Chionodes electella occasionally develop

3b From bulges, club- and barrel-like swellings of branches or stems arise
Viscum album subsp. abietis

4a On young shoots or on needles => 5

4b Developing buds severely stunted, globular swollen and disfigured, hard and browned. Mites inhabit strobili, apparently causing deformation and atrophy. A. alba, concolor, pectinata: Trisetacus floricolus

5a On many curved needles of ± shortened side shoots => 6

5b Lower third of needles predominantly with brown or red swelling, up to 2 (3) mm long, especially rotund-oval to compact spindle-shaped at base and laterally protruding, expanded over only one or over both needles. Larvae orange-yellow, jumping. A. alba and foreign species: Paradiplosis abietispectinatae

6a Top of shoot slightly shortened. Needles of young shoots weakly swollen, ± tuft-like upwardly converging, exposing wax stripes on the underside; many white woolly aphids between the needles during April-June. Abies spp.: Mindarus abietinus

= Between the needles are pale green aphids of Mindarus obliquus occur in white fluffy wax, resembling those of M. abietinus. Contrary to that species, no malformation of the needles occurs.

6b Needles on the stunted tips of young shoots, predominantly of smaller plants, accumulated, bottle brush-like, partially downwardly deflected. A. alba, nordmanniana etc.: Dreyfusia nordmannianae and/or D. merkeri

6c Another inhabitant on bark of Nordmann fir, also alternating with Picea orientalis: Dreyfusia prelli

Last modified 13.v.2020