Tomato Fruit Rotten

Question

Why do my tomato plant fruits start to rot and fall the ground. The leaves are yellowish and rotten.

Answer 1

This can happen for many, many reasons. It may have wilt, blight or another common tomato disease (https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-diseases.htm).

It could just be that the plants are not getting enough water. Without enough water, they will let the fruit die to try to save itself.