Plant Parasites of Europe

leafminers, galls and fungi

gallers on Gnaphalium

Dichotomous table for gallers on Gnaphalium

(incl. Filaginella, Laphangium, Omalotheca, see also Helichrysum)

by Hans Roskam

1a On above-ground parts => 2

1b Roots with 2–3 mm long, spindle-shaped swellings, on which occasionally some lateral roots have developed. G. uliginosum: Meloidogyne hapla

2a Whole plant, or major parts, deformed by aphids or cercopids => 8

2b Galls on shoots => 3

3a Spindle-shaped or globular galls of almost constant shape, but of various size => 5

3b Malformations of various shape and nature => 4

4a Galls on young, often severely stunted, plants. Basal parts, especially stems, also including the leaf bases, spongy, swollen, with many eelworms inside. G. uliginosum: Ditylenchus dipsaci

4b Sometimes strong swelling of the stem on the tip of ± developed shoots or the inflorescence. Leaves clustered, with swollen base, abnormally pubescent. G. sylvaticum: Cause unknown – ? gall mite

5a Galls spindle-shaped, with larvae inside => 6

5b Rotund, up to 5 (10) mm long galls; the inside containing whitish-yellow, later on rust brown, spore masses; predominantly on root collar, occasionally concentrated in groups. More rarely small galls on higher stem parts, even in the inflorescence. Laphangium luteo-album, G. sylvaticum, G. uliginosum: Entyloma magnusii

6a Inside the galls are larvae with head capsules => 7

6b Spindle-shaped swellings, up to 6 mm long and 4 (5) mm thick, usually in upper stem parts, the inside with a sometimes laterally situated whitish larva without distinct head capsule. G. sylvaticum, uliginosum: Actinoptera discoidea

7a Hard ovoid, one-chambered swelling in flower head or stalk. One larva. G. sylvaticum: Acentrotypus brunnipes

7b Spindle-shaped swelling on terminal part of shoot. With a yellowish-white, transversely lightly pink striate caterpillar with pale to dark brown head inside. Laphangium luteo-album: Eucosma albidulana

8a Caused by aphids => 9

8b Shoot stem usually stunted on one side, leaves clustered, the leaf blades curved downward, ± curled and dark green close to the froth-covered nymph. G. sylvaticum: Philaenus spumarius

9 Central part of rosettes deformed; or top of vegetative shoots, also the inflorescence, with shortened and sometimes twisted stem; leaves, sometimes capitula, clustered, rolled, curved. Aphids white frosted by copious secretion of wax. Filago arvensis, germanica, lutescens; Gnaphalium sylvaticum, uliginosum: Pemphigus populinigrae

9b Top of shoot stem stunted, leaves clustered, curved. Aphid bright yellow to yellowish-green, 1.5–2 mm long, without secretion of wax. G. sylvaticum, G. uliginosum: Brachycaudus helichrysi

Last modified 8.v.2020