Potato leaves going yellow

First year growing potatoes. The ones in tubs have very large and dark healthy leaves, maybe too much manure? but the ones I planted directly into my garden are smaller leaves and plants and some are now going yellow.
My soil is sandy but I added manure before I planted anything, I have used an all purpose vegetable food too and yesterday thinking it may have magnesium deficiency added something for that.

Will yellow leaves affect the potatoes?

 

Thank you. I have found a website for identifying potato leaf problems http://www.hbci.com/~wenonah/min-def/potato.htm , I am torn between it being a nitrogen or magnesium problem. I tried the pharmacy for Epsom salts but they don't have any, think I will have to get someone to bring some over. Hopefully the product I bought will work but it is in a granular form and may take a while to get to the trouble.

 

When did you plant the potatoes Louise - and what variety are they ?
I see you are in Brittany where spring comes early.
First earlies can be ready in 8 weeks. I've harvested potatoes in May in Scotland.
When the potatoes are ready the top growth goes yellow and dies off.
Could that be your problem ?
If they're earlies and been in the the ground 8 - 13 weeks, dig one lot up and see what you have there.
Hope you get a great crop.

 

I planted the first ones in the last week in march, they were belle de fontenay. They haven't taking much earthing up (compared with the ones growinng in the pots) and they haven't flowered yet, whereas the ones in the large pots have developed buds and I think will flower in the next week or so. The really yellow one is at the edge of the plot, so I will have a dig and see if there is anything there.

 

Hi Louise. Belle de Fontenay is an early potato. 13 weeks and ready. You planted them in March. Do the sums.
I never worry about potatoes flowering - some do and some don't.
When the top growth dies down - they're ready for sure.
Enjoy.

 

I pulled up the weakest of the yellow plant yesterday and found one good sized new potato and then a load of marble sized ones . The magnesium etc mix that I put on hasn't revived the yellow plants yet but hopefully it may stop the others going the same way.

 

Hmm, on the very top yes but I put lots of rotted manure in and that seems to hold the moisture quite well further down, the soil wasn't soaking but nicely damp I would say.