Shriveled stem after third set of leaves

[curbiechris]

I have gotten shriveled stems very early on during early seedling stage but not at this point of grow. What's the main cause? Disease?

 

[big315smooth]

ive seen this before but looked it up and couldnt figure out why or what caused it

 

[MJPassion]

Fusarium maybe?

If it is...
Throw out that soil.

 

[AgentPothead]

Oh that little brown area, that's a fungus I'm pretty sure they call it damping off. It normally doesn't hit a plant that large, you are probably overwatering if I had to guess.