Tomato malformation

I'm in my first year of growing a few tomato plants in tubs/pots so forgive me if this is a stupid question. A couple of my plants are producing tomato like the one in the photo. If left on the vine they develop a rotten hole where the green is. Any advice please?

 

Hello and welcome to the forum, it looks like blossom end rot. It could be the variety or uneven watering.

 

Usually due to uneven watering during the formation of the fruit, but seem to remember something about a calcium deficiency.
It does look like blossom end rot, but just to be sure is this the flower end or the end that was attached to the plant?

It could be blight if its that end.

 

Blight is usually brown not green and usually the bit that's attached to the plant.

 

It's not the end attached to the plant.

 

It's the flower end

 

BER then as Logan first said.

 

Thank you for your replies. Not sure what to do about it though. I water when the weather demands it and don't when it's rainy.

 

Where have you got the plants, are they in the ground or in pots?
The damaged fruit just bin them, some might be ok if they look ok.

 

It's too late to do anything about it now but you cannot depend on the weather for when to water. You need to keep the soil/compost as evenly damp/moist as you can. it's especially important when the flowers are opening as a drop in water will cause what you have experienced.

If you still have plants with flowers try to keep the plants well watered - but don't go "overboard" with lots of water every day - excess is as bad - if not worse - than underwatering. The trick is to keep an eye on them & to always try to make sure they have sufficient water.

You don't say if they are in a greenhouse or planted outside. In a greenhouse it's much easier to keep an eye on watering, outside it's rather more difficult.

 

They're in pots.

 

Not going to help for this year now but try to use a growing medium with ph of 6.5-7.5 , by adding lime to the mix if required, when potting on .Also consider the ph of the water you use

 

Not watering when its rainy is actually a good reason it could happen, often, unless its torrential rain pots can actually stay dry at the base during the summer months.

Its just something you get used to judging by poking a finger in the top of the pot, it can be very wet on the surface inch or so and bone dry lower down, because that is where the plant is drawing its water from.

 

It is indeed caused by calcium deficiency, calcium is obtained via the roots and flows up but cant circulate so when water is short the plants growth can cause deficiencies. Magnesium however doesnt have this problem. I think the plants will scrap older leaves too to scavange it so it decreases the overall health of the plant.

That said, uneveness does factor in since the plants can adapt fairly well to CONSISTENT drought. What they cant handle is extreme swings. I had some toms in a tiny pot that would completely dry up and they would get through it happily: until blight obliterated them at least.