Plant Parasites of Europe

leafminers, galls and fungi

gallers on genus Mercurialis

Dichotomous table for gallers on Mercurialis

by Hans Roskam

1a On parts above ground => 2

1b Roots with nodular swellings. M. annua: Meloidogyne hapla

2a Inducer living inside galls => 4

2b Inducer living and/or fruiting on gall surface => 3

3a Young leaves of disfigured shoot tip curled. M. annua, perennis: Aulacorthum solani

3b Orange-yellow, soon dusty, spindle-shaped, ± distorted bulges of various length on underside of main venation, on petioles as well as occasionally on young stem parts. Patches developing on leaf blades are small, rotund and not swollen. M. perennis: Melampsora populnea

4a Stem or leaves with localised, well defined galls => 6

4b Malformations usually extending over several organs => 5

5a Large parts, sometimes the entire plants, including primordia of flowering parts, with vitreous, pearl-like, compound small warts; these often join into crusts or ridges and variously disfigure the severely stunted plants during their development. M. perennis: Synchytrium mercurialis

5b On M. annua. Young plants severely stunted. Internodes spongy, swollen, pale green. Leaves distorted, with ± swollen stalks and veins. Ditylenchus dipsaci

6a Rotund, one-chambered swellings on stems, leaf- or inflorescence axial parts. Containing a single curved larva. M. annua. Kalcapion semivittatum

6b Slender, narrow and compact, about 5–30 mm long, soon browned upwards roll of leaf margin. M. perennis: Thrips fulvipes

Last modified 18.xi.2023