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The curse of Blossom End Rot is caused by insufficient calcium. Insufficient calcium is not usually due to a shortage of calcium itself but to a lack of water. Water being the method by which calcium travels round the plant. No water to carry it – no calcium.
But what if there were insufficient calcium in the soil – how can this addressed? By liming i.e adding lime to the soil.
Lime is usually added to the soil to raise its pH, to increase the alkaline balance of a soil. This is especially true of sandy soils where rain and water wash easily through, taking or ‘leaching’ nutrients with them. Calcium is what makes a soil alkaline.
And calcium is introduced into the soil in the form of lime. ( It helps at this point, to disassociate any links your mind might make to small, green, citrus fruit, think instead of those limes as ‘red herrings’ in this context.)
And calcium is also the nutrient needed to build a plants’ cells – and if cells are properly built – BER doesn’t occur.
In this day and age useful (and not so…) products come with catchy and solution-orientated names. So lime, with its simple (and pH misleading) name is a bit of mystery. Here I try and decode it. It starts with quarried chalk or limestone. And then becomes :
Calcium carbonate – ordinary lime (CaCO3). Ground to a fine powder and variously referred to as: garden lime/carbonate of lime/ground limestone/ground chalk.
Quicklime or burnt lime – calcium oxide – chalk or limestone heated in a lime kiln.
Slaked or hydrated lime – calcium oxide – treated with water, making it calcium hydroxide.
But no matter how treated, all limes revert to calcium carbonate when incorporated into soil.
Dolomitic Lime, slightly different, in that it is ground from quarried rock and in addition to calcium contains magnesium.
So all these limes raise the alkalinity of the soil and are a source of calcium. One thing not to do though is apply any kind of lime to the soil at the same time as incorporating manure. They react with each other and result in valuable nitrogen being lost (from soil to atmosphere) in the form of ammonia.
{ 7 comments… read them below or add one }
That’s an interesting post – and well researched too. The curse of blossom end rot has appeared in my tomato patch on the Gold Medal. Only one fruit is affected as yet; two brown patches appeared on its sides. I’m leaving it on the plant for now, but if it spreads it’ll come off and sit in my ‘ripening dish’ for a while, leaving the plant to deal with the remaining fruits in its own way.
Perhaps I’ve under-watered; I usually water every two evenings unless the weather has been hot and sunny. Big fruits probably require more water and calcium, which is probably why beefstakes seem prone to B.E.R. The plant looks perfectly normal, but I may have missed it out or skimped its water last Thursday. either way I’ll keep an eye of that variety now.
At least I know what’s going on, thanks to your informative posts. Thank you, it’s all good.
Glad it was useful. I feel all the better for knowing what lime is really is – and why it gets referred to in different ways ! In older gardening books I’ve read it seems it would have been applied to soil as a matter of course; which isn’t how we garden now. The other place it came up was in reference to preventing club root brassicas.
You say about skimping on water last Thursday – that’s the missing bit for me – is how long the period between cause and effect. How long from when there’s a water shortage – to noticing the fruits are affected. But without doubt it’s the beefsteaks and plum which are the most prone. Which given that I water all mine at the same time it has to be the volume of water not the frequency.
Yes, the drawback with the poly-shelter is that it’s difficult to reach in and see past the forest of leaves and target the water correctly. But I’m also unsure of the time between cause and effect, it’s just that I noticed the problem on a non-watering day. It would be interesting to find out, but that’s not the sort of experiment a tomato fan goes in for…
No- to sacrifice tomatoes in the name of research would be wrong ! This unwarranted ‘experimenting’ is plenty !
I’ve revisited some notes I made from a talk I attended – way back in the spring – so wasn’t quite as attentive to the detail as I would be now – cos my notes read ‘BER – lack of efficient calcium absorption – calcium is very slow to move’ !! So there we have it , calcium, the tortoise of the plant nutrition ! and now if I was in the audience again – I’d be the pedant of the plant world – how slow is very slow !
Still next time when they ask ‘has anyone got a question’? mine will be fastest hand up first !!
my tomato plants do well blossom and start putting on fruit and then start dying from bottom up…the leaves on the lower limbs turn yellow and then brown and die and this moves up the plant…what could be wrong?
my tomato plants do well,,,they blossom and start putting on fruit and then start dying from the bottom up..the leaves turn yellow and then brown and then the next limb up does the same things..what can be wrong?
Sorry to hear your plants are suffering. When a plant puts on new leaf growth, the new leaves need nutrients/minerals and if none are coming up from the soil, then the new growth will take it from the old growth – i.e from the old leaves and with the minerals gone those leaves start to suffer and will die off. And yellowing is usually a magnesium deficiency. So do make sure you are feeding your plants – or that the compost/soil is new each year if you are growing in pots.