I have a number of tomatoes who are now 6 weeks old. They are still under t8 lights 16 hrs a day and in 18oz solo cups. Just a few days ago (5), I transplanted them from the foam cups to the solo cups. I am using miracle grow potting mix and just fertilized them for the first time after transplanting. Yesterday, I noticed a number of them had wilting leaves, like when they need water, but it was just the lower leaves on the lower stems. I also noticed some leaves appear to have yellow spots when looked at from the top and when turned over, those yellow spots are little clear bumps. The plants are in a 7x10 ft room. The door is kept closed and it does get plenty warm and humid in that room with the lights going. The have been doing great until now. I have pruned a number if lower branches now due to them wilting.