Plant Parasites of Europe

leafminers, galls and fungi

gallers on Lycopersicon

Dichotomous table for gallers on Lycopersicon

(= Lycopersicum. ‒ Comp. Solanum)

by Hans Roskam

1a On parts above ground => 4

1b On roots or subterranean stem parts => 2

1c White, velvet cover on all parts of the plant, even underground. Attacked parts turn brown and wither. The conidia (in fact, sporangia) are ovoid or lemon-shaped, with an indistinct apical papilla. They are formed at the tip of seemingly undifferentiated hyphae, that here and there show irregular swellings. Phytophthora infestans

2a Nodular or slender spindle-shaped galls, on roots located distant from surface => 3

2b Buds or adventitious buds of subterranean stem parts, also roots, developing into smaller proliferations, exceptionally up to 20 mm long. Synchytrium endobioticum

3a Nodular swellings, often many and ± coalescing. Meloidogyne hapla etc.

3b Roots usually with shorter or longer, sometimes interrupted, slender, 2–3 mm broad swellings and sometimes excessive development of side roots; this ‘root beard’ is usually situated above the galls. Globodera rostochiensis

3c Tips, often of many roots, slightly swollen over various lengths. Plant often conspicuously stunted. Also many eelworms inside and outside the tissue: Pratylenchus pratensis

3d Root with rounded galls, usually several together like a string of beads; on tomato in glasshouses. Nacobbus cf. aberrans

= Nacobbus serendipiticus (tomato eelworm) is causing spindle-shaped galls on roots in glasshouses

4a On leaves and flowers => 6

4b On stems, sometimes encroaching on leaf midrib => 5

5a Up to 20 (30) mm long, rotund bulge, mainly on root collar, secondarily also on higher stem parts. Agrobacterium tumefaciens

= In cases of the moderately frequent “tomato cancer”, better known as “bacterial tomato withering/drooping” the causer is Corynebacterium michiganense

5b Pale green, spongy, ± expanded swelling, often associated with distortion of ± stunted parts. Ditylenchus dipsaci

6a Various curls or rolls, often of several terminal leaves, caused by aphids => 7

6b Malformations of flowers often with bladder-like swelling, extensively conjoined calyx leaves as well as largely stunting of partially greened corolla leaves and stamens and sometimes enlarged and disfigured ovaries on plants with reduced, often bulging leaves. Stolburg disease

6c Individual flower or part or all of inflorescence greened and leafy (phyllanthy), very haired, containing mites. Aceria lycopersici

7a Aphid dull-black, about 2.5 mm long. L. esculentum: Aphis fabae

7b Aphids pale yellowish to green, 1.8–2.9 mm long, siphunculi pale at base, darker, with a dark spot at tip. Aulacorthum solani

7c Aphid green, often with a dark, green longitudinal stripe on back. Body spindle-shaped oval, glossy in adults, dusted with greyish wax in froth-covered nymphs. 1.7–3.6 mm. Siphunculi brownish, ¼–⅓ of body length, twice as long as cauda. Alates with pale brownish-yellow thorax, otherwise lacking pigmentation on back. Macrosiphum euphorbiae

Last modified 20.v.2020