[Mark's Sussex Allotment]

Variety Swift
Ventilation is ok, could be better
Looks to be all potatoes (all 4 pots showing signs)

[Headgardener22]

It looks like a virus to me. Though I don't know why you would have one if you've used bought-in seed potatoes just bad luck I suppose (though that doesn't help).

Most viruses are transmitted by greenfly, check if you've got greenfly in the PT.

I would move them out of the tunnel if you can to prevent any disease spread to other things, they'll need protection from frost but they might infect other related plants like tomatoes & peppers.

Try giving them another feed to give them some extra strength otherwise you might have to accept that you're going to get a reduced crop.

[Mark's Sussex Allotment]

Ok, I'll get them out.

Any chance it could be sun scorch? Or under watering?

[Yorkie]

Doesn't look like either to me.

Keep an eye out for possible frost overnight later this week.

[strider84]

Hi,

I don't know personally but looking up in my 'bible' it looks like magnesium deficiency


I have a pic from my book but not sure I can post it here? perhaps a moderator can advice on whether I can or cannot.

[Mark's Sussex Allotment]

Here's another picture from tonight.

It's on 3 different plants now, out if 4.

I've taken them out of the tunnel now incase it's fungal?

[RJR_38]

It looks like what I had on my spuds last year (my first year) and I cut them down panicking it was blight. After lots of opinions on here and looking online it seemed it was magnesium deficiency and I should have dosed them with Epsom salts (my soil is quite acidic I think). I am on the look our this year!

The spuds were absolutely fine by the way - just a bit smaller than they should have been because I cut them down too early.

[strider84]

In short my bible suggest first symptom is yellowing of tissue between the veins which begin to turn brown and brittle.

If it sounds like the above then it sounds like Magnesium deficiency.

[Mark's Sussex Allotment]

I think I may have over fertilised them then!

Oooops

[Headgardener22]

Your recent picture looks very different to the first one, there look to be perfectly healthy leaves in the background whereas on the first picture, all the leaves looked affected which made me think it was a virus.

[Mark's Sussex Allotment]

I think I've found out what it is.

Manganese deficiency.

It could be caused by fluffy soil, cold nights or over liming.

Anyone know anymore about this?

[tangojulie]

Have a look at this http://customers.hbci.com/~wenonah/min-def/potato.htm, it has lots of colour pictures of various deficiencies in potatoes. You can also click on the index at the bottom to get pictures for other plants.

The colour values are a bit off as the pictures are quite old, but the notes are helpful, particularly in distinguishing between two options.

[Mark's Sussex Allotment]

Thanks. It looks like Manganese Deficiency, but could be Manganese toxicity.

I found out that there were no drainage holes in the pots, so it could be that the fertiliser was too intense?

[Headgardener22]

Thanks. It looks like Manganese Deficiency, but could be Manganese toxicity.

I found out that there were no drainage holes in the pots, so it could be that the fertiliser was too intense?

One thing I've found in the past is that you're more likely to harm things by overfertilising than underfertilising.

[DD.]

Agreed , and the lack of drainage is not going to help.

I've found in the past that on one patch on my plot next to the paths where it always seems wet, the spuds are not so good and they often suffer from swollen lenticles! 

How come you didn't notice the lack of drainage holes when you planted them?