Plant Parasites of Europe

leafminers, galls and fungi

gallers on genus 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 18.xi.2023