First, one of top five most common questions on entire web site.

black bottoms reverse?

No. Compost them.

Dolomite lime/expired Tums tablet in planting hole at planting is the larger cure, along with consistent water and plenty of mulch. Now, consistent water and mulch is all you can do. No sprays, no egg shells. Problem likely near over as toms should have sufficient roots to uptake water.

Dan

I feared that that would be the answer, Dan. My next question is this: is this a problem only with Roma's? Or should I be putting crushed eggshells or Tums in all of my tomato beds?

Thanks for your patience,
Karen

I think Dan has it correct on all counts.

Variety may make a difference but size is likely to be more important. Cherries are supposed to be immune to BER, altho' a somewhat larger cherry (& and somewhat wierdly colored) Snow White had BER in my garden.

Remember, BER is a physiological problem and not caused by a disease organism. When the fruit and plant is making rapid growth, there may be a shortage of fluid in the tissues. Calcium seems to be very much involved in the movement of fluids in and out of cells but most soils have plentiful calcium.

Steve

I don't think there's enough soluble C in eggshells to make a difference in a meaningful time scale. That is: takes too long to become available, and by the time it is you've rotated your crops.

When I lived in Sacratomato - zero precip from June-Oct - the old-timers there who grew in the best tomato-growing region in the country taught you to plant deep and straight, something with C in the bottom of the hole, and consistent water, consistent water, consistent water early on. After some time, there are enough roots to take care of the job.

My experience is like Steve's: the bigger the fruit, the better the chance of BER. I'll get maybe 3-4-5 a year many years, this year none (probably the rain).

Dan

BER is why I don't plant romas in my garden anymore--I opt for the other paste tomatoes, such as Amish paste or my personal favorite, San Marzano. I do think that crushed eggshells help a bit--I actually use only self-watering containers, and I crush them into the water reservoirs at the beginning of the season, but I concur with Dan--it's probably too late for those already showing the dreaded black spots. I am a salvager, however, and if they're not TOO black and cruddy, I'll still harvest them and then cut out the black part--be sure to check inside, as the black can spread further inside than it does on the outside. Someone will probably chime in and say I'm lucky to be alive after eating those, but I haven't ever had a problem and always cut out all (and then some) of the black spots. I just can't stand to waste any of that time and effort!
Good luck, and better plants next year!

Amish paste or ...San Marzano

These are what I grow for paste. And I can see Ca being soluble in a reservoir.

Dan

I was having the same problem with my potted Cherokee. It was in too small a pot, as the plant grew, it just wasn't getting enough water. Finally broke down and repotted it in a whiskey barrel size planter. With regular watering, no more rotten ends.