My Blc has just contracted something. One of the leaves has a
1/4in/6mm round black spot near the tip. The tip itself has not been
affected, there is some yellowing around the area, the area itself is
thin and filled with necrotic tissue which looks "wrinkled".

The plant is sitting in about 20-25kLux of light (where it has been
for most of the summer) in a steady 22 degrees and 45-55%
humidity. The humidity has started rising as winter approaches. There
is less air exchange - we are regularily hitting 0C during the nights
now. The only thing that has changed is that I have been redecorating
the hall and there is dust more or less everywhere. Could the dust be
a carrier of something? There is no visible molds where I have been
working.

Any idea what I should do about this? I can't get hold of any brand
chemicals, but I can mix my own from whatever is used in chemistry
labs if someone has a recipe. There are no labs around I can send a
sample to for analysis. How do I stop this from happening again?

It is on a new leaf as well.

Geir - unhappy