tomato withering

most likely its just your cotyleons falling off.

This may help ID troubles:

Tomatoes need mucho sunlight, and a soil temp of 70F - 85F.

If you like weekends, thank a union.

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I've used propagators before. Not for tomatoes though. But I've found most plants need to adjust to the new environment outside the propagator. Because you are taking away their humidity and most likely giving them more natural light. On your window sill. Also you didn't say what the light conditions in the propagator are. As they grew in a high humidity environment. possible less light. Barring nothing else is wrong. The sun is burning them, or the less humidity has dried the leaf edges out. They should pick up after an adjustment period. The wilting leaves should be irrelevant.

Diesel.