Plant Parasites of Europe

leafminers, galls and fungi

gallers on Ligustrum

Dichotomous table for gallers on Ligustrum

by Hans Roskam

1a On vegetative organs => 2

1b Flower buds inflated, thickened, unopened, usually normally coloured. Containing pale yellow larvae. L. vulgare: Placochela ligustri

1c Root with rounded or spindle-shaped swelling, 2–5 mm across; containing eelworms, some may be glistening white pear-shaped females with eggs. L. vulgare: Meloidogyne ardenensis

2a On leaves => 5

2b On buds or axial parts => 3

3a On axial parts => 4

3b Several axillary buds, rarely the apical bud, slightly swollen, stunted, developing leaves often only scale-like. Malformation resulting in compact, ± pyramidal witches’ broom-like structures. L. ovalifolium, vulgare: Aceria loewi and/or Aculus ligustri

4a Axial parts, mainly at base, with conspicuous proliferations, up to walnut-size, soon woody, irregularly wrinkled, on surface, dark-brown. “Bacterial cancer” L. vulgare: Agrobacterium tumefaciens

4b Bark swollen, with rimmed irregular depressions, containing causer. L. ovalifolium, vulgare: Chionaspis salicis

5a Malformation of many leaves at shoot tip => 6

5b Leaf blade with rotund, yellowish-green pads, sometimes slightly swollen if on venation, bearing cups on underside. L. ovalifolium, vulgare: Puccinia obtusata

6a Axis of young shoots and stalks of young leaves shortened. Infected leaves loosely clustered. Prociphilus bumeliae

6b xis of young shoots not shortened; usually deflected from the tip, bearing many, distant, downwardly rolled or slightly curved leaves, sometimes twisted, yellow- to rust-spotted. L. ovalifolium, vulgare: Myzus ligustri

Last modified 21.v.2020