Looks like Blossom Bottom Rot. Don’t let your soil dry out if you can help it. Easily recoverable on further fruit if treated.
Thanks! They are thirsty beasts. I water every day but I guess I need to up my game.
How are you watering? I used to spray my tomato plants with a shower-end hose but had much better results from just sitting the hose on the soil and watering the soil. Less water is lost to evaporation and it also reduces the chance of fungus in the leaves.
I water the soil
I don't know what your set up is like, but ollas are a good way to keep soil moisture constant. Youtube has plenty of advice on homemade ones from terracotta pots. I keep a string anchored and dangling to the bottom of each of mine to avoid drowned bugs and lizards.
Not really contributing much with this, but I agree with your assessment. From what I understand you should also remove any dead blooms that didn't just fall off as well.
Correct me if I'm wrong, but blossom end rot doesn't ruin the whole fruit, but just makes it undesirable.
Looks like blossom end rot to me, my plants suffered from this last year. You should try supplementing with calcium, that's what I've done this year and I have not had this issue.
Tomacco, clearly
You need cal mag, this is blossom rot
Cal mag?
Blossom Bottom Rot is a calcium deficiency which can be cured by frequent watering. So less water more often is better than a good soaking once per day. If you aren’t able to prevent your soil drying out then I presume adding Calcium magnesium (cal mag?) should also help. I’m certainly no expert but that’s my understanding.
Gardening
A place for gardening and plant pics