I don't know about San Marzano tomatoes. All of my seedlings are doing great except for these, they are really puny looking. I usually supplement with dolomite when this happens but some say doesn't do any good. The DOP canned variety from Italy makes the best marinaro on the planet.

Basically all the paste types are prone to BER early in the season simply because of their shape. IME San Marzano is no more prone to it than any of the other paste types.

Once the plants/weather stabilizes it goes away.

However given your zone and time of year I have to assume these are being frown in a GH, correct? If so then the artificial growing conditions could be contributing to the problems and you may have to intervene somehow.

Stabilizing the soil moisture levels more helps a great deal but you'll have to figure out how to do that based on your set up. Increasing the soil and air temps in the GH helps too.

Dave

This post was edited by digdirt on Mon, Apr 29, 13 at 17:58

Yes - they are growing in the GH with non-regulated soil and air temps. We protect them from air temps below 40 degrees and higher than 85 degrees - no soil temp protection (except air temps in the GH) in 30" raised beds - with OS temps as low as minus 4 degrees since they were transplanted to the GH on March 10th.

Thank you both for the information - it appears stabilizing is the problem with these paste tomato plants as our other non-paste varieties planted at the same time are doing fine - so far. The Marzano also set fruit a week or two earlier than the other varieties which may have contributed to the problem.

Here's an excellent thread with an explaination of why BER occurs. Just scroll down a little ways and you will see it. This year I'm going to try a little gypsum and calcium nitrate to supply available calcium when the plant needs it when forming fruit.

Here is a link that might be useful: BER thread

Our favorite tomato expert Carolyn137 wrote an excellent response to a question about Blossom End Rot (BER) and I am quoting it here:

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 research 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

I know some of you have seen this before, but with the number of questions posted about BER (Blossom End Rot), I think Carolyn's incomparable explanation bears repeating. Why try to reinvent the wheel when she explains it so well?

Betsy

Here's another explanation I like from a very well known poster on the Containers forum:

"you add gypsum, the Ca will be immediately available if you water from the top so it can disperse through the soil a little. Be careful because gypsum does contribute to the level of EC/TDS and you don't want that getting so high you burn your plants.
The reason BER occurs is because Ca is not mobile in the plant. The plant can 'borrow N, P, and K from other plant parts and translocate these nutrients to new cells, but since Ca is not mobile, it has to be continually present in the nutrient stream for new cells to form normally. The blossom end has the newest cells in each fruit, so anytime the nutrient stream is interrupted (cultural) or Ca is unavailable, the cells on the blossom end don't form normally. This can occur not only from an actual deficiency of Ca, but also from high humidity (usually coupled with clouds and calm winds), too much/too little water in the soil ..... anything cultural that interrupts the constant and sufficient supply of Ca to newly forming cells in the fruits."

Thanks Betsy.

First, I've been having major DSL problems and it's still not solved, heaven help Verizon, so I don't know how long I'll be on here or elsewhere and have been offline since last Friday.

Just a couple of other points.

Growing in containers is not the same as growing inground whenit comes to BER..

Second, BER iS primarily found with paste type tomatoes, but can affect other varieties as well, so shape is not the determining factor.

THirdly, different varieteis can have different physiologies, which also plays into BER,.

When I used to have my tomato field there were some low spots and after torrential rains some ares would find the plants under water. The normal progression to death of the plant is yellowing leaves, can 't get oxygen and nutriens via the roots b/c the soil is waterlogged, then the leaves turn brown and then RIP.

Some vaiteites would go the death route and others wouldn't go beyind the yellowing leaves and would recover,

So with different physiologies plants handle Ca++ differently as well.

All for now,

Carolyn