Years ago Blossom End Rot was thought to be the result of soil deficient in calcium. Add calcium to the soil was the commonly suggested solution. These days, science has determined that BER is the result of the plant's inability to distribute calcium to the fruit via its internal mechanisms. The soil can be loaded with calcium, the plant just can't get it to the fruit in sufficient quantities.
Plant stress is thought to be the cause. Irregular watering is the most common explanation but strong winds, fluctuating temperatures, etc, can also be factors.
Then there's the fact that some varieties are more prone to BER than others. The plum varieties - San Marzano, etc - can be hit by it while other varieties, in the same bed, with identical growing conditions, escape it. It's happened to me. Very puzzling. There's obviously something in the plum variety genes that makes them susceptible.
BER occurs due to the plant's inability to take up calcium from the soil and transfer it to the fruit due to over-watering. It can also be exacerbated by over-fertilising of the soil.
Last year I grew approx 30 heritage tomato plants in large pots outside and following advice from Italophile they were planted with a gap of 6-8" between the top of the compost and the rim of the pot. They were only watered when the leaves began to flag and when watering I filled the pots and left them to drain.
This meant that sometimes they were only watered once or twice a week.
Fertiliser was applied when the first truss of fruit had set, and then about 3 weeks later - that was all.
We had heavy crops of delicious tomatoes and only one fruit with BER and this was early in the season.
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
Interesting to note that the only fruit we had last year with BER was that odd one which we decided was a stray cross-fertilisation - definitely a plum-shape
PS. I've been looking for this, I'd bookmarked it - thought it was interesting
That's a good explanation of BER. Doesn't address that the plum varieties are more prone to the condition but that would get into genetics. Can't have everything.
I was reading that large verities are more susceptible due to them needing more calcium and that growing in containers can increase the risk of it occurring and that also over feeding when the plant is young increases the risk even further due to the root ball being blocked from taking up calcium. The article also said that you should let your soil almost dry up before watering and to apply something calcium rich to your soil like oyster shell. I think it also said something about maximizing air flow to the root-ball by not over soaking your plants when watering and making sure the soil is light and fluffy by thoroughly breaking it up and not compacting the plants when transplanting them. I cant find the article now but I remember most of what it said.
Think that agrees with what Italophile and I said apart from adding oyster shell - it shouldn't be needed in a well-balanced commercial compost, but if making your own the addition of some ground down oyster-shell would be a good idea (available from stockists of poultry feed as Oystershell Grit).
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
BER will strike any variety if the conditions are ripe for it. I'd love to know, though, what it is about the plum variety genes that make them more susceptible. One day science will get around to explaining it. As tomatoes become a more and more profitable business, particularly for seed companies, more science is applied to them. Exploding a few myths and old wives' tales along the way.
I remember that my great grandma Used to feed her plants the occasional drink of tea not compost tea but the kind we drink. She would brew up tea in the normal way minus the milk and sugar. lol. then add cold water and feed all her tomato plants with it. In fact she fed all her plants with it and I remember her saying to me that it was the way her mum did it and swore by it she said it made her plants more resistant and gave them a boost. Has anyone else tried this
My black Rushian are now about 2ft+ tall and some have just started to form there first flower buds. I'm holding back on planting them out yet though as the weather has turned wet and I don't want to lose my hole lot to blight. I have some polythene coming by courier and I'm going to cover a frame for a green house I built with it and then my tomatoes will go in there until the weather drys up some and then into the garden as the only spot I had for the greenhouse doesn't get full sun all day. I got a bargain on the polythene off Ebay £60 for 3.7m x 20m including delivery so ill probably have some spare to make some cloches.
Posts
Years ago Blossom End Rot was thought to be the result of soil deficient in calcium. Add calcium to the soil was the commonly suggested solution. These days, science has determined that BER is the result of the plant's inability to distribute calcium to the fruit via its internal mechanisms. The soil can be loaded with calcium, the plant just can't get it to the fruit in sufficient quantities.
Plant stress is thought to be the cause. Irregular watering is the most common explanation but strong winds, fluctuating temperatures, etc, can also be factors.
Then there's the fact that some varieties are more prone to BER than others. The plum varieties - San Marzano, etc - can be hit by it while other varieties, in the same bed, with identical growing conditions, escape it. It's happened to me. Very puzzling. There's obviously something in the plum variety genes that makes them susceptible.
BER occurs due to the plant's inability to take up calcium from the soil and transfer it to the fruit due to over-watering. It can also be exacerbated by over-fertilising of the soil.
Last year I grew approx 30 heritage tomato plants in large pots outside and following advice from Italophile they were planted with a gap of 6-8" between the top of the compost and the rim of the pot. They were only watered when the leaves began to flag and when watering I filled the pots and left them to drain.
This meant that sometimes they were only watered once or twice a week.
Fertiliser was applied when the first truss of fruit had set, and then about 3 weeks later - that was all.
We had heavy crops of delicious tomatoes and only one fruit with BER and this was early in the season.
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
Ah!
Good morning Italophile - you beat me to it! 
Interesting to note that the only fruit we had last year with BER was that odd one which we decided was a stray cross-fertilisation - definitely a plum-shape
PS. I've been looking for this, I'd bookmarked it - thought it was interesting
http://ianrpubs.unl.edu/live/g1752/build/g1752.pdf
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
That's a good explanation of BER. Doesn't address that the plum varieties are more prone to the condition but that would get into genetics. Can't have everything.
I was reading that large verities are more susceptible due to them needing more calcium and that growing in containers can increase the risk of it occurring and that also over feeding when the plant is young increases the risk even further due to the root ball being blocked from taking up calcium. The article also said that you should let your soil almost dry up before watering and to apply something calcium rich to your soil like oyster shell. I think it also said something about maximizing air flow to the root-ball by not over soaking your plants when watering and making sure the soil is light and fluffy by thoroughly breaking it up and not compacting the plants when transplanting them. I cant find the article now but I remember most of what it said.
Think that agrees with what Italophile and I said
apart from adding oyster shell - it shouldn't be needed in a well-balanced commercial compost, but if making your own the addition of some ground down oyster-shell would be a good idea (available from stockists of poultry feed as Oystershell Grit).
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
BER will strike any variety if the conditions are ripe for it. I'd love to know, though, what it is about the plum variety genes that make them more susceptible. One day science will get around to explaining it. As tomatoes become a more and more profitable business, particularly for seed companies, more science is applied to them. Exploding a few myths and old wives' tales along the way.
I remember that my great grandma Used to feed her plants the occasional drink of tea not compost tea but the kind we drink. She would brew up tea in the normal way minus the milk and sugar. lol. then add cold water and feed all her tomato plants with it. In fact she fed all her plants with it and I remember her saying to me that it was the way her mum did it and swore by it she said it made her plants more resistant and gave them a boost. Has anyone else tried this
My grandfather used to tip his used tea leaves onto his garden plants. They contain potassium so they can't hurt.
My black Rushian are now about 2ft+ tall and some have just started to form there first flower buds. I'm holding back on planting them out yet though as the weather has turned wet and I don't want to lose my hole lot to blight. I have some polythene coming by courier and I'm going to cover a frame for a green house I built with it and then my tomatoes will go in there until the weather drys up some and then into the garden as the only spot I had for the greenhouse doesn't get full sun all day. I got a bargain on the polythene off Ebay £60 for 3.7m x 20m including delivery so ill probably have some spare to make some cloches.