its probably a fungal infection from the soil.
where did you get the soil?
anyway anti fungal treatments are available. i did read that Hydrogen Peroxide can be used but not for seedlings, probably too strong.
looking at your photo, i think you may have to prepare yourself for the worst.
if you have to start again, junk all the soil and containers and disinfect the grow area properly.
I have used hydrogen peroxide before for sterilization of my setup prior to planting.
IT IS VERY DANGEROUS SHIT, wear THICK rubber gloves, not surgical gloves, cos it burns skin BAD!!! and not a burn like a hot ember but a chemical burn, may look ok externally but under the skin surface it damages the nerves and by Christ it is painful, so be very F%$#in careful. Put it this way, I'll never use it again. I learnt the hard way.
You've been given some good advise above. Start again and if you do decide to use it, not on seedlings.
Seedlings are babies, they need to be nurtured, not beaten into submission. Using peroxide on seedlings is equivalent to disciplining a newborn with a baseball bat IMO.
''Using peroxide on seedlings is equivalent to disciplining a newborn with a baseball bat IMO.''
F**k that made me laugh mate haha.
Yeah I only bought the 3% to dilute 1:10 so it was quite weak. Didnt cop any on the skin and wore rubber gloves just incase.
No chemical burn so I was happy about that,
Was actually looking up H202 and chemical burns before I did it. Not the best idea btw
Plant still not doing well. Paling on bottom growth has continued slightly, growth has pretty much halted.
But stem not really getting worse.
I think maybe only way to go is to snip on a 45 degree angle, swish in some cloning liquid and into rockwool?
Im not even fussed if I come out with a retarded plant just dont want to chuck it haha.
On the other hand 1 seedlin going very well and will be putting a few more into paper towel after a soaking to germinate tonight.
Pics enclosed. Will keep youse updated.