yellowing, browning, and crumbling

[dirtysox]

what causes those syptoms on small seedlings and plants with 4 leaves total?

 

[GeezerBudd]

Waterlogging/insufficient drainage
Nutrient overload
Insufficient Ventilation
Lights too close

There is a guide in this forum to help you figure out what the problem is.
Look under sick plants, problems...

Hope this helps.
Gb

 

[dirtysox]

thanks again