yea if its rotting the stalk, its only going to get worse. Marijuana has a very strong healing capability, but once the fungus/bacteria has penetrated the inner stem, its really over. and if they are only in veg, they have a long time to go and probably wont recover enough to flower. I would "possibly" cut some clones far away from the rot. Rot will travel up the phloem very far from the sight of rot. If you cut a clone 3-4 inches away and there is any sign of brown/grey or any color other than green, its too late, it will only spread. You really need to make a bleach water and clean the entire room up down top to bottom/ everything, whats the rh? good luck