Plant Parasites of Europe

leafminers, galls and fungi

gallers on Pelargonium

Dichotomous table for gallers on Pelargonium

by Hans Roskam

1a On parts above ground => 4

1b On root collar or roots => 2

2a Conspicuous gall formation on root collar => 3

2b Roots with nodular swellings. Pelargonium spp.: Meloidogyne hapla

3a About walnut-sized proliferations, irregularly tuberculate on surface, at first succulent, whitish, then browned or blackened, ± globular. Pelargonium spp.: Agrobacterium tumefaciens

3b Clumpy accumulation of severely stunted shoots, swollen in all their parts. “Leafy gall”. Pelargonium spp.: Rhodococcus fascians

4a Leaf blades variously deflected, with conspicuous necrotic spotting and strong malformations. Pelargonium spp.: Aulacorthum solani

= The “Pelargonium aphid” occurring in greenhouses in central Europe, Acyrthosiphon malvae lives on P. grandiflorum, more rarely on P. peltatum, tricolor, zonale, and affects especially the terminal shoots, which are conspicuously crumpled. The aphid may transmit Pelargonium-Virus 1, which, by localised stunting, results in bulging and occasional rupturing of the leaf blades of the often severely distorted plants

= Cultivated “geraniums” (Pelargonium zonale and hybrids) are often affected by Puccinia pelargonii-zonalis with cinnamon uredinia at underside of leaf and teliospores when present formed in the uredinia

Last modified 15.vi.2020