Astrophytum seedlings red spot.

[claudekim1]

Hi guys. I have some astrophytum seedlings growing right now. And im wondering what these red spots are. I applied sulfur on the red spots just incase its fungal. The funny thing is i have frailia seedlings and a few golden barrels in there. And none of them are affected at all. The only thing ive done is add some cacti fert at 1/4 strength. (The red spots were there before i added fert)

http://imgur.com/gallery/oaqz8HS

edit: i picked the skin with a large patch of it (on one of the pictures) and the skin like basically ripped away and a empty cavity was inside. im guessing its rust. i think the sulfur is helping with the other seedling.

[MikeInOz]

Some of them look a bit stretched. More light, lower humidity and perhaps spray with a systemic fungicide like banrot if you are worried.
Is there a good supply of calcium in the mix? Why do the seedlings have free water on them? That should never happen.
Are they warm? At this stage temps should not fall below about 17C at night and should preferably rise to about 27C during the day.

[claudekim1]

my seedlings are in a 100% humidity chamber.. (like the baggie method) idk about the calcium. i could add eggshells i guess. The temps are like 22 at night and during the day like 26 ish. Tho i think it gets warmer sometimes.

[claudekim1]

Some of them look a bit stretched. More light, lower humidity and perhaps spray with a systemic fungicide like banrot if you are worried.
Is there a good supply of calcium in the mix? Why do the seedlings have free water on them? That should never happen.
Are they warm? At this stage temps should not fall below about 17C at night and should preferably rise to about 27C during the day.

Should i move the unaffected ones in to a different pot? Also the sulfur seems to have worked on a few of the smaller infections.

[MikeInOz]

Some of them look a bit stretched. More light, lower humidity and perhaps spray with a systemic fungicide like banrot if you are worried.
Is there a good supply of calcium in the mix? Why do the seedlings have free water on them? That should never happen.
Are they warm? At this stage temps should not fall below about 17C at night and should preferably rise to about 27C during the day.

Should i move the unaffected ones in to a different pot? Also the sulfur seems to have worked on a few of the smaller infections.

I would be inclined to watch them closely to see if the area of damaged tissue increases. if it does, then perhaps separate them.