Oh dear! It looks very much like potato blight, there isn't a cure and most experts say burn the leaves and plants, but other say try a strong nettle leaf tea sprayed on all the leaves. Blight can infect greenhouse toms just as much as outside ones. It could also just be a mineral deficiency, mostly due to too much water, use a fortified foliar feed if it is.
If the leaves start to turn brown ad sort of powdery beofre falling into slimy black then it is the dreaded blight-pick any uninfected fruits and ripen indoors-watch like a hawk-and burn the plants, remove soil if in greenhouse, if outdoors don't grow pots or toms for a couple of years in that place. Hope that's worst case scenario and it isn't that dire!
I'm not sure but it could be one of two things - tomato leaf mould or (more likely I think) magnesium
deficiency. Worth googling I think. Sorry I can't be more help. x
I'm not so sure it is blight as the first signs of that is brown blotches on the edges of the leaves which spread until the leaves are killed, and the stems show blackened patches.
I would pick off the worst affected leaves and keep a careful eye on the rest.
I agree with Maggie, it looks more like magnesium deficiency and the quick cure for that is a dose of epsom salts.
If they are container grown the cause could be under feeding or even over feeding of a high potash feed as this can lock up the magnesium, making it unavailable to the plants.
Thank you for all your replies!
These plants were grown indoors from seeds (in March) and planted out in a raised bed in May. They grew beautifully indoors in the conservatory and were way over a foot high when I put them out but they definitely have taken a beating with all the wind and rain we’ve had. Lots of the plants are in flower and couple of plants have tiny tomatoes on them but not as many as I thought I’d see – maybe its still early.
I hope it’s a magnesium deficiency which can be treated which by looking at the websites provided (thank you Maggie) seems to be the case. I will treat it and hope it recovers.
It’s a bit discouraging, but being able to harvest some of my rondo carrots and a handful of mange tout for dinner yesterday did make me think – this is SO worth it. This is my first time growing veggies so I’m very excited.
it looks like early blight to me. my potatoes have it at the moment. its not like the dreaded blight tho so your plants wont rot and die. i think the foliage just starts to dry out. i think its treated with epsom salts but id google it to be sure.
Unfortunately you can't treat early blight with Epsom salts. It's a fungal disease and is best treated with a copper-based fungicide if you're organic or something stronger if you're not.
We still don't know exactly what the problem is with Natalia's toms. According to the blightwatch website there are confirmed case is east Kent and suspected in west Sussex but conditions are improving for its spread so it could pop up anywhere now.