Plum tomatoes

Question

I have plum tomatoes in pots. The first ones to come out are still small and green, but are turning black at the bottom. What happened?

Answer 1

It sounds like blossom end rot, a fungal disease. These articles may help

https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-blossom-rot.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/applying-calcium-nitrate-for-ber.htm