Plant Parasites of Europe

leafminers, galls and fungi

Pseudomonas syringae pv. tagetis

Pseudomonas syringae pv. tagetis

on Cirsium, etc.

Cirsium arvense: plants diseased by Pseudomonas syringae pv. tagetis

Cirsium arvense, Ooijpolder, 26.v.2011.


The tips of the shoots are chlorotic. The cause is the compound tagetitoxin, that is produced by the bacterium and and interferes with the development of chloroplasts.

host plants

Asteraceae, oligophagous

Cirsium arvense.

distribution within Europe

(PESI, 2020).


The well known phenomenon of chlorotic thistle tips formerly, also on this site, was associated with the rust fungus Puccinia punctiformis. Still unexplained is why this phenomenon in the field seems to be limited to creeping thistle: according to the literature the pathovar tagetis infests several more Asteraceae.


Gronwald, Plaisance, Ide & Wyse (2002a), Lydon, Kong, Murphy & Zhang (2011a), Rhodehamel & Durbin (1985a).

Last modified 11.viii.2020