Plant Parasites of Europe

leafminers, galls and fungi

gallers on genus Dahlia

Dichotomous table for gallers on Dahlia pinnata

by Hans Roskam

1a Leaf blades arched and curled, caused by aphids or cercopids => 3

1b On root collar or roots => 2

2a Roots with small nodule-shaped swellings. Meloidogyne hapla

2b Conspicuous succulent, cauliflower-shaped proliferations on tubers, on root collar or stem base. Agrobacterium tumefaciens

2c Irregular proliferations of the stem base, combined with an abundant development of buds. Rhodococcus fascians

2d Extensive malformations usually accompanied by R. fascians. Aphelenchoides fragariae

3a Deformities caused by aphids => 4

3b nfected young shoots severely stunted, the leaves curved downwards, curled, dark green close to the froth-covered nymph. Philaenus spumarius

4a Aphid black. Aphis fabae

4b Aphid green. Aulacorthum solani

Last modified 17.xi.2023