sallyg said:Not sure- Looks like powdery mildew, will they go outside soon?
DaisyI said:If you plan to keep your tomatoes indoors, they need full sun and a fan to move the foliage. The leaves on your plant make me thing something fungal also. Plants in stagnate air (not moving) will grow all sorts of molds, mildews and fungus not to mention bugs.
The fan will also help with pollination as they are breeze pollinated.