Beginner Gardening: Cracks in my tomaotes, 0 by TXBBQ

TXBBQ wrote:
Thanks for the response. So what is a recommended source of potassium for them? I have some Vigoro Tomato plant food, as well as Miracle Grow plant food that supposed to be great for veggies. Should I use more of these and water less? I live in north TX, where the temp often runs 100+ every day. So I thought they needed large amounts of water. Am I wrong on that? How much should I water?

Also, what causes these yellow spots that look like some sort of disease?

Thanks for all advise and direction.