Young Papaya Trees dying

Hello,

I have about 12 papaya young trees, around 1 year old, started them from seeds and moved them to large containers with a well-drainage soil mixture. during the summer period i had them out in the sun and they were growing fast, but as winter came I had t move them into the house, where they have a good amount of light from the windows and heating.

but now they are dying one by one, first the leaves start to curl and face downward, but there still green and arent dry, then the bark start to lean down and eventually fall from the point where the bark meets the soil.

I have attached photos

Please help, whats causing this, is it a disease, rot, or the cold weather?

I can't say it's not a disease, however from trial and error, this is a look all too familiar in my own trial and errors, and may not be the issue you are experiencing.
Transplanting small PawPaw was an exasperating experience in that they seem to deflate before my eyes. Over time I got the message on how much they seem to react at having their roots messed with. Finally I would not transplant any from quarts until they were all roots. At that point I would only up pot them one or two sizes and that resulted in a much better success rate. Each up pot was mostly undisturbed root clusters.
To this day if Papaya re-seeds itself in the garden and I attempt relocation, it's a 95% fail rate. Ultimately they grow a large tap root (like a carrot) and seem even fussier if disturbed. Contributing are shorter days and low humidity. Very much humidity lovers.
Hoping for your success!

Papaya hate too much water and 24 hours with their roots in the water will kill them. Your fotos look exactly like my trees when they start to die due to flooding.
By the way, I can usually transplant very young trees, otherwise I don't bother.
Good luck!

I don't think it's a disease. These trees need to be outdoors. I know if it gets cold (in Florida this means a frost or freeze) they can be covered but they need the real sun and the air outdoors meaning humidity, even when cool or cold outside. I would place them back outside, in the shade first and then slowly move them back into the full sun so they don't burn.

Good Luck