Stem Rot

[ShapeUp]

I don't have pictures but I have seen more than once of mostly main trunk getting some form of rot. It seems to turn brown then you see a stem coming off, start to die. Everything above the spot starts dying one at a time. I thought it might be some powdery mildew. Not sure but it attacks the whole plant if left. It's there a name for this? I don't see a remedy. I have tried several things to try and cure it but it seems to continue. I have seen whole leaves get dark and get what looks like a black covering or spotting also. Always trying to learn more.

 

[Gingerbeard]

By your description, time to give up. Autopsy your plant. Check the roots. Open stems, branches, and trunk to look for bug larvae and rot. It is very difficult to stop that sort of crown/stem/root rot when it gets going.
Black 'dirt' or 'soot' on your leaves might be mold. It is not WPM.
If the pictures I'm sure you've seen elsewhere look like what you have, that's what you have.

 

[Rwise]

Botrytis is what it sounds like, any so called cure will also kill the plant. So you must look at preventative measures, like keeping moisture off with fans etc..

 

[9fingerleafs]

Very true. Another one is called fusarium. Probably one or the other killed your plant. Both fungi. Both can attach roots too