MaxMustermann wrote:
I've been doing some more research on the internet and I'm
starting
to think that the problem is not aphids at all.

The plants (leaves and stems) have brown and black spots (not
more
than 1mm diameter each) and they don't move. They are stuck
underneath the leaves and along the stems. They can also be
found
on top of the leaves. The spots are not actually within the
leave
membrane but on the outer side... sort of miniscule domes.

As I said, I've pruned a plant by removing all leaves and
treating
the stems with a soap mixture and also with pesticide. When new
leaves grow, the spots come back again.

Could it be a different kind of insect or a fungus infection?

Thanks,
Max

Scale perhaps.

--

Travis in Shoreline (just North of Seattle) Washington
USDA Zone 8
Sunset Zone 5