Yellow potato plant

[bionear2]

In the middle of a vigorously growing patch of Edzell Blue potatoes, one plant turned completely yellow.
Dug it out, and most potatoes seem fine, except two that had white patches, and were a bit soft.
Reference books seem to be no help - any suggestions?

[bionear2]

[ceres]

Have you tried here:

http://www.potato.org.uk/department/knowledge_transfer/pests_and_diseases/viewer.html?type=diseases

[saddad]

 :-\

[Kepouros]

I`m afraid I can`t tell you what it is, bionear2, but I have a plant of Nadine which developed similar symptoms.  However, I deliberately left mine to develop, and I can inform you that it now exhibits all the signs of stem rot - but not blackleg as there is no discolouration.  I shall leave it a bit longer before I dig it up and get the magnifying glass on it.