[smellykipper]

is this caused from temperature changes or is it blight ?

[DD.]

Could be a virus such as mosaic.

There have yet to be any reported blight outbreaks in the country.

http://www.potato.org.uk/fight-against-blight/blight-incidents

[BabbyAnn]

What about sun scorch (the plant on the left is fine, the one on the right seems to have older leaves affected.

Or how about magnesium deficiency?  It can't do any harm to try some epsom salts

[Yorkie]

My first thought is magnesium deficiency.  Are you feeding them with anything already?

[Italian Bob.]

Sun maybe , maybe wind if they have been out  , i have simliar problems and they are recovering just fine  , btw they now outdoors and holding there own (south east )

[Goosegirl]

Doesn't look like a virus to me as the discolouration seems too even. I think it is some nutrient deficiency, so feed with a dilute feed.

[sunshineband]

Are they all in the same compost? I had an issue with two of my plants looking pale, and they were in a different compost to the others.

Several feeds later they perked up, and now are beginning to catch up with the others again.

The green veins against yellow leaves is usually a nutrient deficiency, often Magnesium

[smellykipper]

i will give them a weak feed and see how they get on, i did add a little blood,fish,bone to the compost ?

many thanks for the advice

SK

[Headgardener22]

Sunlight/cold? Because the 3 plants (I assume they're all the same variety) are variously affected, could it be the different conditions. I assume you've watered them all the same so its possibly differences in the quantity of sun they're getting or overnight temperatures.

[smellykipper]

the one on the left is a shop brought a Shirley the other two are Megabite and golden sun, they was in a grow box but have been hit with that cold night we had last week in a unheated pt

[Yorkie]

FBB is a good general purpose fertiliser, but it might be worth a quick dose of Epsom salts in case it's magnesium deficiency as mentioned by others.

[Headgardener22]

the one on the left is a shop brought a Shirley the other two are Megabite and golden sun, they was in a grow box but have been hit with that cold night we had last week in a unheated pt

Ah.
Different varieties behave differently to the same conditions and need different treatment. I would give epsom salts as suggested plus a weak feed of tomato fertiliser (you've got flower buds so that should be OK).

[Yorkie]

the one on the left is a shop brought a Shirley the other two are Megabite and golden sun, they was in a grow box but have been hit with that cold night we had last week in a unheated pt

Ah.
Different varieties behave differently to the same conditions and need different treatment. I would give epsom salts as suggested plus a weak feed of tomato fertiliser (you've got flower buds so that should be OK).

I disagree in this instance about the tomato fertiliser at this point.

One of the reasons tomatoes can get magnesium deficiency is because of over-use of tomato fertiliser, which prevents take up of the magnesium.

[Headgardener22]

the one on the left is a shop brought a Shirley the other two are Megabite and golden sun, they was in a grow box but have been hit with that cold night we had last week in a unheated pt

Ah.
Different varieties behave differently to the same conditions and need different treatment. I would give epsom salts as suggested plus a weak feed of tomato fertiliser (you've got flower buds so that should be OK).

I disagree in this instance about the tomato fertiliser at this point.

One of the reasons tomatoes can get magnesium deficiency is because of over-use of tomato fertiliser, which prevents take up of the magnesium.

I agree with your comment about over fertilising. However, we don't know how smellykipper has treated the plants so far. Because these three plants are from different sources (and we don't know whether there are others with different features), he may not have fertilised them at all which could also be a problem.

[JohnB47]

I recon its been the cold. I'll go with your plan for giving them a weak feed.