Plant Parasites of Europe

leafminers, galls and fungi

gallers on Chaenomeles

Dichotomous table for gallers on Chaenomeles

by Hans Roskam

1a Malformations on leaves => 3

1b Malformations on stems => 2

2a Witches’ broom-like malformations with only little, often reddish leaves on sap-rich, whip-shaped shoots. C. speciosa: Inducer unknown, presumably caused by a fungus, Exoascaceae

2b Considerable cancer-like proliferations on basal stems. C. speciosa: Agrobacterium tumefaciens

3a Malformations on several terminal leaves caused by aphids => 4

3b Leaves with ± protruding bladder-like, pale-green or reddened swellings, later on withering, which at maturity are occupied by a grey-white layer of fungal asci. ? C. speciosa: Taphrina bullata

4a Leaves rolled inwards and crumpled, clustered nest-like on the ± shortened shoots => 5

4b Leaves obliquely bent downwards and ± rolled. C. japonica: Myzus persicae

5a Aphid with rather long siphunculi. Chaenomeles spp.: Aphis pomi

5b Aphid with short, thick, green siphunculi. C. japonica, speciosa: Rhopalosiphum oxyacanthae

Last modified 20.v.2020