Hi,
I'm in No Virginia, zone 7. I've had EBs for about 7-8 years, then a break for 5 and now I'm back. This year, I have more BER than I've ever seen on my plants before AND I diligently gave them the "snack" 1x week pretty much from when they were 2 feet tall and just as blossoms were starting. Now I know that's not a given... but I was hopeful...

First, is it too late to do anything? I have 9 healthy plants with lots and lots of green tomatoes on them. Some look fine so far (e.g., it's been a mix of BER and non-BER on the same plant). One or two rotted before even blushing. I think that was the Brandywine. It seems to me this late in the season, I just need to live with it/cut the bad ones off. If it's not too late, what do I do? is this when I add a certain kind of lime one time?
Second, the cause? Here in VA it's been pretty hot and humid. Also this year I got off to a slightly late start, planting in end-May instead of mid-May. I'm also using varieties that I didn't use in the past, namely Early Girl, Big Boy, and Celebrity. (Also trying Mortgage Lifter and Brandywine, but they're behind). In the past I used Jersey Boy. I suppose it could be due to all three???
Thanks,
JB