My Potatoes are rotting and its not blight.

[George the Pigman]

This year my potatoes were looking good for a bumper crop. However when I dug the first earlies (Lady Chrystal) I noticed quite a lot of rotten tubers. I dug a maincrop (Pentland Hawk) and it was even worse - about 70% rotten. The tubers have black/blue blotches on the outside and sometimes white  spots on. On cutting the tuber the rot is clearly coming in from the outside as the centre looks OK The rot is in the shape of brown rings. The plant tops have shown absolutely no signs of blight. Generally the tubers nearer the surface seem to have survived better.
We had (in Birmingham) lots and lots of rain in June then very dry ever conditions since (desperate for rain now!). I have clay soil and my plot is on a slope.
Any ideas what's happening?

[George the Pigman]

[Tee Gee]

Your description does not ring any bells for me perhaps these pictures might help you diagnose the problem:

http://potatoes.ahdb.org.uk/gallery/potato-diseases

http://potatoes.ahdb.org.uk/gallery/potato-disorders

[Crystalmoon]

Hi George I am sorry I have no idea what is wrong with your spuds & I am really sorry you have lost what was going to be a great harvest. I had a look at the links Teegee gave....really shocked to see how many things can go wrong with spuds! Hope you find an answer soon.

[George the Pigman]

Thanks for the links TeeGee.
The closest fit is Rubbery Rot - a fungal disease that affects tubers but not haulms. I suspect the downpours we had in June (we had 2 inches in one day!)together with drainage problems on my clay soil may be the cause.