[svalli]

That looks so familiar to me. I have been battling with this years. It seems to affect some varieties more than others. Black Cherry and some potatoe leaf varieties used to be the worst. Surprisingly this year I did not see any of this problem. I moved my seedling shelves to a room, which gets morning sun and used fluorescent lights for tomatoes. Also I skipped my normal bottom watering habit.
Earlier years the ones, which got the problem and did not die usually started to recover when moved to the greenhouse. That is why I try to get the plants to the greenhouse as soon as possible.

Sari