Black Spot On My Toms

[alavahalf]

Has anyone had any experience of this... it's a first for me. Having asked the best gardener I know , he seems to think it is caused by either overwatering or underwatering....
But which is it ?

http://i68.tinypic.com/25uqonb.jpg[/IMG]

This year I have approx 30 tomato plants around the affected one and no others have the same problem. They are all watered at the same time each day.

[Togo]

Looks a bit like sour rot alav. Do they actually smell sour?

http://vegetablemdonline.ppath.cornell.edu/DiagnosticKeys/TomFrt/Sour_Tom.htm

[paddywak]

Sounds like Blossom End Rot
https://www.rhs.org.uk/advice/profile?pid=395

[Davemano]

Put white spirit on then scrape spots off with your fingernail. Oh dear sorry, wrong thread.
Seriously I was always told the black spots were due to over watering.

[alavahalf]

At this stage I haven't actually smelled them ... that's ae job for tommorow. Going by the links it would suggest underwatering. But as they all get drenched together, you would think that other plants would suffer if they are underwatered ?

[paddywak]

It's more irregular watering Dave,too much or too little can both cause it.

[alavahalf]

Dave .. if I put white spirit on them I wont smell the rot .. 8-)

[Davemano]

O K.

[SlackAlice]

Looks like blossom end rot to me. Caused by irregular/under watering. Surprising how much water they need. I've got a grow-bag with three plants in it, watering about 7litres a day plus capful of tomorite.

[Togo]

http://aggie-horticulture.tamu.edu/vegetable/problem-solvers/tomato-problem-solver/

This is not a bad site alava, considering that its American. Can you send me some sunshine? It has been in short supply up here but is now blazing.

[alavahalf]

We are on the south coast in sussex and seem to have had non stop sunshine for weeks on end. I am watering with a hose pipe most days. Each plant gets a proper soaking as we are constantly getting over 90 degrees farenheit in the tunnel. Today it was 106 degrees when I got there at midday.

[jourdain2]

I got this one year when in France. It seemed to be associated with the variety. It was not resistant to virus, trying to remember the name, began with 'M'. Tasty, but prone to this. 'Marmande', I think. Anyway, that was a virus.

[alavahalf]

The type I have the problem with are San marzano.

[Old_Geezer]

Wow looks like you need more than a spot remover !

Trying to grow tomatoes myself but they fend for themselves at the weekend. Not showing signs of that. (That stated they are still green and small.)

[Chipchopper]

Yes, blossom end rot for sure!
Can be caused by irregular watering, over-feeding, lack of calcium or just extreme weather conditions.

Nasty looking toms....yuck!

[alavahalf]

Today I have seen all the people I would take any notice off and they have said the same ..Blossom end rot. The one person I would ask if there were no others said it is down to irregular watering and the reason that only one plant is affected is because it's roots may be formed very shallow, therefore it may not be receiving as much water as the rest.
Sounds a reasonable explanation I thought.
He also said the answer to not letting it happen again would be to sink a 5-6" plantpot upside down in the soil when I put the plant in the ground in the first place. When watering I am to fill the plant pot a few times, this will allow the main root to get a good drink and not just the surface roots. With it being in a poly tunnel the surface dries out very quickly and therefore the water may not have been getting down to the main root.
Thanks for all the answers.

[Togo]

Well done with your diagnosis alava, properly researched, and understood by all of us who have been interested.

[Old_Geezer]

I have bought something similar to this from my local garden centre.
https://www.healthylivingdirect.com/sp+gardening-plants-plant-care-adjustable-aqua-spikes-set-of-6+31308?gclid=CKy2wICkyc4CFRCNGwodfqsC-Q#fo_c=1415&fo_k=b1fa098a896497f914b0bafe8a716772&fo_s=gplauk
Luckily it came with size adaptors as the spike one doesn't fit the squash bottle that I'm still trying to use up in order to use the bottle. I think it could get water to the deeper roots.

[alavahalf]

Good idea OG .. but this year I have reduced my tomato plants down to about 30. It would be a bit of a chore filling 30 bottles each day.