Well....that's a thing that happened. :(

[Waira]

hey PE! ..looking at the end of that stem, it looks like it might have been a defect in the stem, formed early on,... was she a problem seedling? Any scarring, cuts may have started this, but didn't affect her enough until larger,...

 

[PapaEmeritus]

Looks like Damping Off disease to me. Not sure but would be my first guess. Caused by fungus or disease on the grow medium. Was this new coco? Certainly strange

Yeah, I considered that too. Like @Arthur said though, seems pretty late to me for that to happen. Coco was a mix of older and newer - grew my last run in part of it and it went perfectly.

You can root it. Do you have cloning gel? rooting hormone? If so I will tell you how to do it. It may take a couple months to finish, but it can be done. You could get several clones off of it, and give that a shot too. They are still in veg, it can go.

The plant's well dead at this point, unfortunately. I didn't think you could clone or re-root autos?

hey PE! ..looking at the end of that stem, it looks like it might have been a defect in the stem, formed early on,... was she a problem seedling? Any scarring, cuts may have started this, but didn't affect her enough until larger,...

Heya! See, I was thinking about this and there was a situation where about a week before this, the plant was bumped against the underside of one of my lights when I picked it up to put something under the pot. It looked fine afterwards, but maybe that did it? Other than that she was a total rockstar - no problem sprouting, nada.

 

[Rev. Green Genes]

It can be done, but they are limited in capacity and life span. To me it's worth the effort to see what happens, but it would have had to be done right away anyway. Your mostly right, it's not really advised but possible.