According to Dr. Carolyn Male (tomato goddess):
Yes, I'm here and I'm going to again cut and paste what I wrote before and call your attention to the paragraph below that starts with the sentence..... the old information about BER...... b'c that's the crux of the problem. That is, you'll find some University sites and some private sites and many other sites who still maintain that the single cause of BER is lack of soil Ca++ and don't mention anything else, which is why in that paragraph I said that the old info is going to take at least another generation before the correct info is found almost everywhere.
Here's my cut and paste again.
(With BER there is NO problem with absorption of Ca++ though the roots. The problem is maldistribution within the plant that can be induced by a number of stresses which include uneven delivery of water, too much N, growing in too rich soil, too hot, too cold, too wet, too dry you name it.
As the plants mature they can better handle the streses that can induce BER so usually it goes away.
The two exceptions are first, if the soil has NO Ca++ as confirmed with a soil test, and that's a rare condition, and second, if the soil is too acidic in which Case Ca++ is bound in the soil.
Again, adding lime, egg shells and on and on can not and will not prevent BER b'c absorption of Ca++ thru the roots is OK.
Paste tomatoes are especially susceptible to BER and I think someone in a post above mentioned that.
If you go to the top of this first page and click on the FAQ link and scroll down you'll also find an article about BER in case some of you have never looked at the FAQ's And there's some darn good articles there as well, but I wouldn't pay any attention to the variety list b'c it's way out of date.
The old information about BER being caused solely by lack of soil Ca++ has been shown to be wrong with research that's been done in the last 20 years or so, but it's going to take another generation before the real story gets into books, websites, magazines, etc. Most of the better websites already have the correct information.
BER affects not only tomatoes, but peppers, squash, cabbage, cauliflower, etc., and it's a huge multimillion dollar problem for the industry, which is WHY all that reasearch was done. For instance, when tissues were taken from a plant that has BER fruits and was assayed for Ca++, the normal level of Ca++ was found, it just wasn't getting to the blossom end of fruits. And there's also a condition called internal BER where the fruits look fine, no evidence of BER externally, but when you cut open the fruit the inside is black
Hope that helps
Betsy had added at the end of my article the following, with which I agree.
(So, what it comes down too is: Tums do not work, nor do egg shells, milk, and other "home remedy" treatments. Foliar spray only works in some cases. Time and good management practices work best.)
So, you can believe what I wrote above, or noting what I said about wrong or incomplete information still being out there and make up your own collective minds about BER by doing as much online research as I have in the past 20 years or so. ( smile)