problem with main stem

Hi everyone,
I'm about 4 weeks into my first grow and one of my plants has developed some sort of issue at the bottom of the stalk. The PH is normal along with the PPM. I'm under blue sprectrum florescents and on a 18/6 lighting schedule with coco as a medium. Any help would be greatly appreciated. Thanks.

Looks like some kind of old damage, mabe when it sprouted. I would repot and plant it deeper.

Yeah, I would say it is nothing that is wrong with it now...think of it like the plant's belly button

looks like old damage,why are your roots exposed ?

Those are not the roots, just some of the coco mulch. I think it's too late to dig it up and re plant... should I just cover it with soil? it doesn't seem to have any effect on the plant. My only concern it that the stem won't be able to support itself when I go into flower

You could try it. just mound it up, wont hurt a thing. Keep fingers crossed too!

Looks like stem rot and if it gets worse the plant will starve. Move about 1/2 inch of soil away from the damaged area and blow a fan on there , reduce watering and only water the outer soil not around the stem.

What causes stem rot? The rest of the plant is very healthy. Have you encountered this problem before?

Good catch, I didnt think of stem rot...

is it soft? bendy? moist? it could be rot, ive had that happen at the base of the stalk before, seems its a great place for rot to form, moisture from the soil, and low light levels. if it is moist and gooey a bit down there, try some fungus/rot/mold killer, spray some 1/2 strength all over the plants (if in veg) and some just poured onto the soil, and the affected areas.

It's not soft or bendy, and the rest of the stem and plant looks healthy and happy with no other signs or symptoms of disease. I'm just starting the 4th week of veg so I can run to the hydro store and pick up some mold spray. Do you think I should cut back on the watering until it clears up? Heres a pic of the whole room and the infected plant is the one in the middle (closest to you)

Looks like a problem I had 3 weeks back... https://www.rollitup.org/marijuana-plant-problems/486689-nebula-has-collar-rot-foot.html Listen to BUDS.

Were you able to correct it? Did you plant recover?