I wonder if you could help me identifying the problem. I couple of young C.dealbata developing plants show spoted leaves: winding white traces and small spots; some of the spots turned into granulous yellowish (picture enclosed). This developed gradually, starting with the white winding pattern. Patterns differ on upper and lower surface. Not all the leaves affected; cut out affected leaves. Is it a virus? I'm not experienced with Centaurea.
The winding white traces are the effect of a leaf miner, an insect, not a virus.
Thanks. Presumably it might spread to neighbour plants in the green house (different kind of plants) or garden. Can I prevent it?
Leaf miners rarely cause a great deal of damage, and some are specific to certain species (i.e. will not spread randomly to other plants)... and Centaurea dealbata is an extremely tough plant, virtually impossible to kill. If the leaf miners bother you, you can kill them simply by pressing the leaves between your fingers... they are tunnelling between the inner and outer surfaces of the leaf.
Thank you!
