Tomato seedlings

Question

What causes leaves to curl or fall off of tomato plants started from seed and about 7 weeks old?

Answer 1

This could be watering issues; too much or too little.
Lighting issues or even a fungus called dampening off.

Here are some links that will help.

https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-tomatoes-from-seed.htm

https://www.gardeningknowhow.com/garden-how-to/seeds/what-is-damping-off.htm