Blossom End Rot Puzzle

[Python15]

Good morning kind people. I'm currently growing some Coure di Bui and Ailsa Craig Toms and I've noticed some of them have developed blossom end rot. Now I hear you cry "Not Enough Water" but I guarantee they are sufficiently watered, usually half a gallon, sometimes a whole gallon per day in hot weather. Now the fruit that is rotting is well up the plant. None of the lower fruit seems to have it. My question is, could it be very warm conditions causing this; as in all the water being taken up by lower fruits? I ask this as I've had my greenhouse door closed as I dont want the same aphid slaughter I had last year and it has been exceedingly warm these past few weeks. Any help (or ridicule) would be appreciated!

[nickdub]

Its always not enough water, as you say. What you don't say is what sort of growing medium you are using eg peat based compost, and whether you are growing them in containers or not. One possibility is that the compost has got dry parts to it and the water you are pouring in the top is just running through and not wetting the compost at all, obviously if this the problem then standing each pot in a bucket of water usually is enough to wet the growing medium thoroughly again.

I've had similar problems in the past and this year have opted to put in place a gutter watering system with wicks from the tomato pots into it so that the plants can take up as much water as they need - I'll post about it at the end of the season to say who it worked out for me.

[Python15]

Hi Nick, thanks for the reply. They're in 25 ltr buckets of peat based compost with the buckets sat in trays. Now I usually pour from the top down and continue until the tray is full (1 1/2" deep) and monitor this closely to make sure the trays never dry out. All this water's gotta be going somewhere! I've had plenty experience with blossom end rot in the past and it's always been due to irregular watering (my own fault) but this seems different.

[Penellype]

Blossom End Rot is causes by calcium imbalance in the plant, which is often due to irregular watering, but can be caused by other factors, one of which is very high humidity in unventilated greenhouses.

There is more info here: https://www.rhs.org.uk/advice/profile?pid=395

[nickdub]

Hi Python,
You sound like you know what you're doing and I'm just going by personal experience here as I'm by no means a tomato expert. If they were my plants I'd try picking up a couple of the buckets which hold plants that have the problem to see if they feel heavy enough. My take is that later in the year as the roots of the plants go all through the compost it's easier to keep it thoroughly wet, but sometimes early in the year part of a bag or bucket of compost can go bone dry and then its only soaking which will wet that section again.

[ameno]

If it's only affecting the tomatoes higher up the plant then it could be that the temperatures are/were too high.
At this stage in the plant's life, it's root system won't be as developed yet, so it's capacity to draw up water is limited. In order to get water up to the top of a tall plant, it has to fight against gravity, so the upper fruits will inevitably receive less water than the lower ones. If it is them also particularly hot, thus increasing water loss through the leaves, it may be that the plant simply can't keep up, and can't send enough water high enough up the plant to keep the fruit sufficiently supplied.

As for wetting dry compost, the easiest solution is to add just a drop of washing-up liquid to a gallon watering can. Washing-up liquid is a wetting agent, that is, it reduces the surface tension of water and thereby allows it to stick to other substances much better. That tiny concentration of washing-up liquid won't harm your plants in any way.

[Nicos]

I am going to try putting some crushed egg shell into the final pots ( You lot are well ahead with your plants!)

One thing I was wondering is if it's worth watering with some soluble calcium tablets from the pharmacy? It's not something I've tried...and was just wondering if that might work/ help?

[ameno]

I am going to try putting some crushed egg shell into the final pots ( You lot are well ahead with your plants!)

One thing I was wondering is if it's worth watering with some soluble calcium tablets from the pharmacy? It's not something I've tried...and was just wondering if that might work/ help?

I imagine that would be very expensive. Plus most tomato feeds have calcium in them.
Also, lack of soil calcium is rarely the issue, anyway. Rather, it's because the plant is unable to properly absorb it, usually due to lack of sufficient water.
And if you're going down the soluble calcium route at all, I would think using it as a foliar spray would be more efficient than watering it into the compost.

[Python15]

I read a thing from a fella called John Harrison that adding calcium nitrate can help but it seems way too expensive a solution for the likes of me. My initial reason for the post was to see if anyone ever had a similar problem. This may all be down to the fact that I've kept the greenhouse door shut, so here's what I think I will do, please feel free to correct me. I'm going to make a screen door like you see in American houses to keep the aphids out (hopefully) and keep the greenhouse cooler. Would this be ok or am I dreaming?

[nickdub]

As before I'd start with the compost - if it's too awkward to weigh the buckets, then I'd just push my hand inside the compost to see if any of it felt dry.

Personally I just wedge the door open on sunny days if the temp seems very high, and close it at other times, but I am a bit of a bodge artist.

[ameno]

I read a thing from a fella called John Harrison that adding calcium nitrate can help but it seems way too expensive a solution for the likes of me. My initial reason for the post was to see if anyone ever had a similar problem. This may all be down to the fact that I've kept the greenhouse door shut, so here's what I think I will do, please feel free to correct me. I'm going to make a screen door like you see in American houses to keep the aphids out (hopefully) and keep the greenhouse cooler. Would this be ok or am I dreaming?

What other plants do you have in your greenhouse? Because aphids don't bother tomato plants. Quite the opposite, in fact - the hairy and slightly sticky stems of tomatoes trap small flying insect like aphids and they the die and drop to the ground, feeding the plant. I've never found aphids to be a problem for cucumbers, either, although not for the same reason.

[Python15]

This year it's tomatoes x6 a courgette and a cucumber with a dozen marigolds. Last year was a nightmare. I had chillies and sweet peppers which seemed to be aphid magnets. They killed off all my cucumbers with mosaic virus but the peppers didn't really suffer at all. I'm not sure but when the cucumbers were biting the dust one of my tom plants went with them and another was terribly stunted. Both showed signs of aphid casts.

[ameno]

You sure it wasn't white fly? Aphid infestation rarely causes that much damage, and if it is bad enough to cause that much damage, you would see the aphids themselves in very large number (hundreds, maybe even thousands), not just the shed skins.

[Snoop Puss]

If you've got any hardwood ash, that makes an excellent source of calcium for toms. I've not had any trouble since I started using ash.

https://en.wikipedia.org/wiki/Wood_ash#Fertilizers

[rary]

I usually open the greenhouse doors in the morning and place a wooden frame fitted with enviromesh over it and this let's the air in and as the temperature increases the auto vents open the windows and even though there might not much air movement it seems to work as I have not had blossom end rot for many many years