Purple tomato leaves

[noz03]

This year I started growing tomatoes on my balcony for the first time. I have 3 plants and apart from one that I call the runt of the litter the other two are doing great, especially the cherry which I have to keep pruning it grows so fast!

Over the last week though I noticed that especially the cherry plant's leaves are starting to get purple spots on them! Similar to this(image from google): http://i.stack.imgur.com/MaDUm.jpg

I searched google and some people seem to think it is fungus, some say aging of the plant and some say it is malnutrition. So I don't know what to think!

I cut off most of the purple leaves a few days ago, quite a lot actually because I thought it was fungus, but they keep coming and I can't prune any more.

Anyone have any ideas?

The plants are in 2kg of soil per plant. I give them a table spoon each of organic fertilizer from chicken manure every month and keep them well watered. It's not super sunny where I live but they get some, and plenty of breeze so fungus now sounds unlikely.

Please help

[Snoop Puss]

I'm not sure what the copyright rules are on taking images from other people's sites. I think you might find a mod will remove the image. But out of interest, what did it say on the site where you found the image?

More generally, the bottom leaves do tend to become discoloured and drop off before the top ones.

But a couple of questions: what do the leaves look like underneath (any evidence of pests) and what are the night-time temperatures like?

Where we live, we've been down to 11 �C at night and lots of the leaves on my tom and aubergine plants are showing signs of having got a bit cold. Purple leaves are often an indication of cold, as I understand it.

[veggiechicken]

One site with that image suggest magnesium deficiency.............and welcome to the Vine

[Scarlet]

What size are the pots? I think they may be too small. Also feeding with chicken manure fertiliser once a month just isn't enough feed especially if they are in pots. Feed weekly with a tomato feed.
...and you say "breeze" are they kept outside? Where are you?

[Jungle Jane]

I was going to say magnesium deficiency too,the patches start off green & get darker,try Epsom salts. if the leaves aren't too badly damaged they can swing back to normal colour so don't remove any more yet. Chicken manure is a high nitrogen feed,at this stage in growth tomatoes need high potassium or tomato feed.

[noz03]

Hmm, not sure i.stacks rules on resharing but I made it a clickable link now just to be sure.

Anyway, I found many such images on many such posts and everyone seems to have a different idea

To answer the questions people asked:

Yes it has been quite cold lately, around 10 degree lows, although my neighbour hasn't had the same problem. The underside of the leaves seems fine, no pests and the purple spots only seem to be on the top but you can see them through the leaf if you look hard. The trough is indeed a bit small for 3 plants although I am keeping the plants under 3ft so thought it would be ok. I will increase the fertilizer though.



But still not sure what this is or what I can do about it, and does it mean my plants are doomed? So far 3 replies and 3 different theories. I guess purple leaves can be a sign of many problems

[veggiechicken]

You can expect several suggestions because you haven't given us much to go on - just a photo of someone else's plant.
Sounds to me like the plants are overcrowded and in need of a decent feed to keep their strength up.
What varieties of tomato are they? Are they bush tomatoes or cordon/vine (need staking and sideshoots removed)

[Scarlet]

Yes, without a photo of your plants it's all guess work.
But I would say "malnutrition" is a possible contender - having 3 plants in a trough and feeding once a month on chicken manure pellets when they are flowering/fruiting isn't giving them a good chance to flourish to be honest...so you could try to fix that first if you can't take a photo of your own. If it was pests you would see them. As VC has said, what variety are they, are you pruning correctly and how much sun are they getting? When you say "well watered" how often are you watering?

[Potstubsdustbins]

Malnutrition is a definite front runner. The pots are to small should be at least 10/12ltrs and they need a lot more nutrients than their getting.

I presume you water between feeding this will flush what nutrients there is in the compost out. A good regime would be water twice, feed once.

[Penellype]

I grow my indoor tomatoes in 3 litre pots, which are far too small but do produce a reasonable crop on the windowsill. The plants always suffer from magnesium deficiency - this is a photo of affected leaves:



It always affects the bottom leaves first and once they have gone this colour they won't recover. The leaves higher up will be greener and the plant can be saved by feeding with tomato food which is high in magnesium. Providing that some leaves are still green the plant will still be able to produce fruit.

[ConfusedRhubarb]

I've got a few purplish patches on one of the greenhouse toms that I was ignoring as they are not the dread blight. But reading this thread I think maybe it's because of cold nights a week or so back, they are right next to the window. Thanks everyone for the reminder that tomatoes do this.