Plant Parasites of Europe

leafminers, galls and fungi

gallers on Celtis

Dichotomous table for gallers on Celtis

by Hans Roskam

1a Malformations of leaves => 2

1b Buds swollen on young twigs, about 8 mm long and 3–4 mm broad. C. australis: Aceria bezzii

2a Galls caused by aphids => 3

2b Galls caused by mites. Pale green, irregular and coalescing protrusions on upper side of leaf; corresponding depression on underside lined with whitish, 1-celled, simple, acuminate, thick-walled hairs with swollen base. The infected areas are twice as thick as the healthy ones. C. australis & subsp. caucasica: Reckella celtis

2c Galls caused by gall midges. Conspicuous blister gall on both sides of leaf; the blister is covered with short white hairs is on the underside, a concave depression covered with dense white fibers on the upper side. C. australis subsp. caucasica: Celticecis caucasicae

3a Pea-size protrusions on upper side with abnormally pubescent, bosselated surface. Often the complete leaf blade is covered with these galls; infected parts are fleshy and thickened. If several terminal leaves are infected, the twig is thickened and the leaves clustered. C. australis: Pemphigus sp.

3b Terminal leaves discoloured and curled. C. australis: Unidentified aphid

3b Irregular, discoloured protrusions on upper side leaf blade. C. crenata: Unidentified aphid

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