Q.Tomato Problems
I am growing Cherokee Purple tomatoes from seed, and am getting black patches as well as sunken fruit. What is causing this and can it be stopped?

Certified GKH Gardening Expert
Some of that is heat related, and from allowing the soil to dry out just a little too much between waterings. Some of it is from calcium/magnesium deficiency.
Here are some articles that will help:
https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-blossom-rot.htm
https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-tomatoes-guide.htm