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Blossom-end rot - can I still turn this around?

Our San Marzanos are suffering from blossom-end rot. We've had only four fruit set so far, and every one of them has this problem. I've mulched and started watering only in the mornings in an attempt to stop this, but so far, it's had no effect. Googling around, the consensus seems to be that BER is tough to stop once it's started. Has anyone here been able to turn around a tomato plant with this problem? If so, what did you do? I'm starting to feel like there will be no San Marzanos this summer.

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  1. Actually, I think it's a situation that resolves itself when the temperatures stabilize themselves. Do occasional deep watering and be patient.

    Is it possible what you were reading was referring to the progress on individual tomatoes only ? That's the only way it makes sense to me.

    1. I heard that it has something to do with not having enough calcium. My father in law usually tosses some powdered milk into his fertilizer for this reason. I'm trying it this year (a couple of tablespoons per plant), but it is too early for us to tell if it will have any affect...

      1 Reply
      1. One detail I neglected to mention - these are in a container, not in the ground.

        1. get some dry milk powder and epsom salts and mix about a half a handful of each into a gallon of water to give to your plants. This will give them calcium and magnesium. I generally get BER on the first tomato off each bush in a season but it corrects itself after that. Good luck!

          1. >>Has anyone here been able to turn around a tomato plant with this problem? If so, what did you do?<<

            Yes.
            High-calcium lime sprinkled on the soil and worked in through your regular watering. Have done it with some success. (It won't reverse any BER that is already happening, but will stop it from happening on future fruits.) Have also used potash, which (I believe) corrects a nitrogen overabundance the soil -- that can also cause BER -- successfully.

            Info is from "The Organic Gardener's Handbook of Natural Insect and Disease Control" by Ellis and Bradley. It's been a super-useful book over the years.

            1. While it's true that BER is a calcium problem, it's more often a calcium UPTAKE problem than an actual soil deficiency. When the plants are growing vigorously in the spring, they can't seem to get the calcium distributed evenly, resulting in BER on the first tomatoes that set. In general, as the season progresses, later tomatoes will be fine.

              However, some varieties are more susceptible to BER than others. I work in a research garden where we do mixed tomato trials. We'll have tomatoes right next to each other, same soil, same irrigation (uneven watering is often blamed for BER, but these tomatoes get exactly the same water), and obviously the same weather, yet one variety will be full of BER and the other not. Paste tomatoes, in general, seem to be more susceptible to BER than other kinds.

              You can let the tomatoes ripen that have BER and just cut off the bottoms, if the tomatoes are big enough. Or else just pick and compost them now, and let the plant concentrate on setting new ones that hopefully will be BER free.

              3 Replies
              1. re: Karen_Schaffer

                Interesting -- so, for example, I see BER happening and add calcium/potash/whatever to the soil. Subsequent tomatoes do not exhibit BER, so I think there's a cause and effect relationship to augmenting the soil; BUT subsequent tomatoes, just left alone, would likely have been okay anyway?

                1. re: harrie

                  Yup, that's the likely story. Great point that it's easy to believe there's a connection when it's just coincidental. If you had enough tomatoes of the same variety in your garden, you could designate part of them to be a control group, then you might see if the calcium/whatever really made a difference. But of course, most of us don't grow lots of exactly the same tomato!

                  It's possible that your soil is low in calcium and needs the boost, but in that case you'd be better off adding the amendment when you plant your tomatoes in the first place. In general, it's not the soil, it's just the timing (or possibly irregular watering).

                  1. re: Karen_Schaffer

                    Blossom End Rot is as stated above more of an "uptake" issue than a soil deficiency problem...Periods of Rain followed by drought or periods of drought followed by rain seem to exacerbate the problem....If you are not adverse to commercial fertilizers then Calcium nitrate applied to the bed prior to planting in the spring, and side dressing at first fruit set seem to almost eliminate the problem...Or has for me for more years than I can remember...I may lose 3 tomatoes per 50 plants, and that's it.

                    Have Fun!