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By Samand

Stirlingshire, United Kingdom Gb

I planted30 Carlingford and 30 Maris Peer potatoes in July for xmas. iIhave drawn them up twice.Now i notice all the carlingford shaws are starting to rot and turn mushy.
It started of when i noticed 2 plants strarting to go of ,i thought it might have been a dog or fox urinating on them, then it has spread along the row
I dug a shaw this morning the original potato is good and hard ,not rotting. the Maris Peer all seem ok
They are planted next to each other



Did you notice the leaves were affected first. Did they develop brown patches and then a few days later the foliage was dead.

I think you have potatoe blight, the only thing is to lift and burn all affected plants and tubers that are rotting.

If you have plants where only the foliage is affected remove and burn. Do not compost. Leave the tubers for a couple of weeks and then check again for rot. if rotted then you have no choice but to dig them up and burn.

Do you have tomatoes nearby which have shown similar symptoms? Toms and spuds are related and so both suffer from blight and the toms may have infected your potatoes or vice versa.

Blight is caused by a fungal disease, phytophthora infestans and is spread by airborne spores.

The disease spreads very quickly, if the temp is 10oC and humidity over 75 per cent for two days or more. (This is known as the Smith period)So if you have a had a few humid days as we have had here, then that will be the cause.

You can prevent blight by spraying with a fungicide such as Dithane.

There is also an organic approved mixture 'Bordeaux Mixture' made up of copper sulphate and lime.

There arguments that Dithane is actually better for the enviroment. Choice is yours.

I would suggest that you treat your other potato crops with a fungicide by spraying every 10 - 14 days and next year buy blight resistant varieties.

My potatoes were affected by blight, they were growing in bags, so luckily not all were affected and I only had to destroy one lot.

16 Sep, 2011


This is the time of year for harvesting your potatoes, Samand, we lifted all of ours for storage a couple of weeks ago. I would cut the shaws off all the potatoes and lift the Maris Peer this weekend, weather permitting. I am not sure what is happening to the shaws of the Carlingford, it could just be blight. In that case, I would leave these potatoes in the ground for another two to three weeks in the hope that the blight spores will die off. Then lift them and store them separately from the Maris Peer - just in case. Put all of the shaws in the rubbish bin, don't try to compost them.

16 Sep, 2011


I think both of you have missed t he fact that Samand planted them in July to have potatoes for Xmas. Samand my understanding is that you need to plant these in a polytunnel or greenhouse to protect them from frost they will not survive outside overwinter. Other than that I would agree that you have got blight in the potatoes and it is unlikely you will get very far with them.

16 Sep, 2011


Mg, my xmas spuds are in bags and doing very well. I shall move them into the garage if the weather gets too harsh as I have no greenhouse, with extra protection from the elements.

Funny thing is I planted 'charlotte' as an early, earlier in the year, she did not flower, now she has lots of flowers.

The potatoes were really tasty, so we shall wait and see what this batch produces.

16 Sep, 2011


Exactly Grannyb you have your Xmas tatties in bags! Sam is trying to grow in the open ground which will not work!

16 Sep, 2011


Thanks for all your help Moon growe, Grannyb, and Bulbaholic
This plot is an old farmhouse garden been lying for several years i thought it would be clear of most diseases
Anyway i will try the cloches on my pot,s
Thanks again

16 Sep, 2011


Sam if you get a frost it will destroy your potatoes. That is why they are all harvested in September, early October. Your tatties for Xmas need to be under cover in a greenhouse or polytunnel.

16 Sep, 2011


Sam it's a temptation to try and beat nature, but if we have the cold severe temps and damp we had last year she will invariably beat you.

I would suggest you lift as MG advisers and next year plant in bags for Xmas, when you will be able to move them to more suitable conditions.

With some plants you can mulch to protect from frost, but spuds leaves are way to high and even covering with a cloche may not help.

Good luck

footnote: the way mine are growing at the moment they may be ready well before xmas, so I shall have to lift and store.

17 Sep, 2011


I 'think' I remember reading that for Xmas potatoes you actually sow the seed potatoes in September...

17 Sep, 2011

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