Plant Parasites of Europe

leafminers, galls and fungi

gallers on Impatiens

Dichotomous table for gallers on Impatiens

by Hans Roskam

1a On parts above ground => 2

1b Broad spindle-shaped to globular fleshy galls on roots, also variously coalescing. I. balsamina: Meloidogyne hapla

2a On leaves or flowers => 4

2b On stems => 3

3a Mainly basal stem part with considerable, fleshy proliferations. I. balsamina, noli-tangere: Agrobacterium tumefaciens

3b Stem, also petioles, weakly to moderately swollen over a length of 5–100 mm, often variously distorted and densely covered with aecia. I. amphorata, balsamina, capensis, firmula, parviflora, scabrida, sodenii; not on I. noli-tangere: Puccinia komarovii

4a On leaves or cotyledons => 5

4b Flower buds swollen, small and unopened. I. noli-tangere: Unidentified gall midge

4c On flower stalks. I. noli-tangere: Semiaphis noli-tangere

5a On leaves => 6

5b The usually completely diseased cotyledons are paler than the healthy ones, often weakly spoon-like, arched upwards; on underside with whitish-grey down of branched conidiophores. I. balsamina, ?capensis, noli-tangere, walleriana: Plasmopara obducens

6a Leaf blade curled and ± strongly curved => 7

6b Leaf blade with rotund, almost bladder-like swellings. I. noli-tangere: Trioza sp.

7a Malformations caused by aphids => 8

7b Leaf blade deflected, strongly curled, especially close to infestation, often deep green; also clustering, nest-like, of all reduced parts, bulging, ± curved and twisted terminal leaves. Impatiens spp.: Philaenus spumarius

8a Apterae are bright green, pink or red, with extensive shiny brown-black dorsal shield, black siphunculi and yellow to whitish cauda; body length 2.1‒3.1 mm. On undersides of leaves along main veins, and later in dense colonies on flower stalks, of Impatiens spp., especially I. balsamina, balfourii, glandulifera, parviflora: Impatientinum asiaticum

8b Apterae are green with an extensive shiny black dorsal shield, black siphunculi and a pale cauda; body length 2.0‒2.7 mm. Singly or in small colonies on undersides of leaves of Impatiens spp. but especially associated with I. noli-tangere: Impatientinum balsamines

8c Leaf blade ± discoloured, curled and marginally ± deflected by black aphids. I. balsamina, glandulifera, parviflora: Aphis fabae

Last modified 15.v.2020