I planted a 1 gal pup of a Dwarf Cavendish banana in the ground in my greenhouse in spring 2021. It grew great that summer, then stopped growing over the winter, and started again the next spring. Last year it reached about 8' by the time it stopped growing in the fall, here's a photo from mid-October, it only unfurled one more leaf after the one unfurling here:
It looked fine for the first part of the winter, nice green leaves for the most part, with only the oldest leaves getting a little yellow from the cold temperatures. Here's a photo from mid-January:
Then, a little over a month ago, the leaves started dying at a rate of about one or two per week, from the bottom up. This was what it looked like by February 20, with most of the leaves dead but the inner leaves still mostly green:
Yesterday, I decided it was completely dead, it was almost a foot shorter than before (shriveled), the cigar was brown:
When I cut into the top, the heart was brown and soft:
As I cut off chunks to remove the rest of the p-stem, it started smelling a sickly sweet scent, similar to fermentation, and by the base it was very gooey and definitely starting to rot:
I had watered it pretty regularly, and tested with an orchard soil moisture probe so I only watered when it was medium-dry or drier. I don't think the problem was watering-related.
There had been a LOT of rain recently, and it's possible there's a deep perched water table that the roots didn't reach last year but they were waterlogged deep this year?
The weather was cold, but not colder than the previous year when it over-wintered fine.
My leading theory is some kind of soil pathogen that was able to attack easier in the winter when the defenses were down, but no clue what pathogen that might be.
Any thoughts?