Plant Parasites of Europe

leafminers, galls and fungi

gallers on genus Allium

Dichotomous table for gallers on Allium

by Hans Roskam

1a On above-ground parts => 2

1b Roots with small spindle-shaped or nodular swellings, up to 6 mm long. Allium spp.: Meloidogyne hapla

2a Locally restricted to expanded, bulging or non- protruding galls => 3

2b Complete plant stunted and disfigured. Leaves as well as sheaths and stems stunted, spongy thickened, curved and sometimes twisted, ± pale green, with undulately rugose surface. Onions occasionally ± bursting, inner scales more swollen than the outer ones, soon rotting. Many eelworms inside the galls. Allium spp.: Ditylenchus dipsaci

3a Galls distinct from the outside => 4

3b The externally normal leaves of A. senescens show rows of chambers in the locally more compact parenchyma, each containing a single larva. Larvae white to yellow. Unidentified gall midge

4a Bulges of minor or larger expansion, with black spore balls inside; at first lead-grey translucent, then with black spore dust when broken open => 5

4b Flat, 1.5–5 mm broad, brown-red bulges on leaves, scapes and sheaths of inflorescences. A. schoenoprasum: Physoderma allii

4c The plant elongates above the bulb. Cultivated Allium spp.: Peronospora destructor

5a Leaves of young plants, also bulb scales, with one to several stripes, about 10–20 mm long, bulging, bluish-green, later-on with black dusting of smut spores. Allium spp.: Urocystis cepulae

5b Yellow spots on ± disfigured leaves. Allium spp.: Puccinia allii

5c Spermogonia on both sides leaf, orange, often visible between the aecia. Aecia on underside leaf, in loose, often circular clusters on large, irregular, yellow spots; cup-shaped, with a white peridium and an orange mass of spores. Allium spp.: Puccinia sessilis

Last modified 17.xi.2023