I've always had some tomatoes with Blossom End Rot. Usually it's just a few of the very early ones. But this year, we have had a lot of them.
These don't look so bad, but I tossed a whole bunch of grody ones into the compost heap earlier this week.
Blossom End Rot is the result of a calcium deficiency. It can be related to low calcium in the soil, but is strongly associated with moisture levels in the soil. Soil that is too wet or too dry prevents the uptake of calcium.
This year, even with the well amended soil, we're definitely having issues with dryness in the garden.
Ha ha, that is a huge understatement... We're on pace to becoming the hottest and driest summer on record. So our tomato plants have gotten way too dry more than a few times. But now that I know the cause, I will be more diligent with the watering. ;-)