What is wrong with these tomatoes?

I grow tomatoes and it always happens, yellow or dead leaves near the bottom. Cut the off and don't worry about it. As the plants age more and more of the leaves and limbs will have the same problem, trim them off. This causes no ill effect as far as fruit production. It is the nature of the plant. You can expect the fruit to get smaller as the plant ages so have a new plant ready to replace the old. No spray or treatment will help.