I have grown potatoes in large pots. One of my pots is looking very poorly. There are black spots on the leaves, hardly any flowers are forming and small growths (some up to the size of a walnut) are growing on the stems. The growths are the same colour as the stems and have leaves growing out of the top of them. The other normal leaves on the plant are not curling up. Is this blight or some other disease? The other potatoes in my garden are fine, although I am keeping this pot well away from them. Could this be a problem with the seed potatoes?

Jo of Greenhill said:



I have grown potatoes in large pots. One of my pots is looking very
poorly. There are black spots on the leaves, hardly any flowers are
forming and small growths (some up to the size of a walnut) are growing
on the stems. The growths are the same colour as the stems and have
leaves growing out of the top of them. The other normal leaves on the
plant are not curling up. Is this blight or some other disease? The
other potatoes in my garden are fine, although I am keeping this pot
well away from them. Could this be a problem with the seed potatoes?


The growths on the stems would not be typical of blight. Blight would
cause dark, greasy-looking lesions on the stem. Something else is
going on.

--
Pat in Plymouth MI

"So, it was all a dream."
"No dear, this is the dream, you're still in the cell."

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In article ,
says...

I have grown potatoes in large pots. One of my pots is looking very
poorly. There are black spots on the leaves, hardly any flowers are
forming and small growths (some up to the size of a walnut) are growing
on the stems. The growths are the same colour as the stems and have
leaves growing out of the top of them. The other normal leaves on the
plant are not curling up. Is this blight or some other disease? The
other potatoes in my garden are fine, although I am keeping this pot
well away from them. Could this be a problem with the seed potatoes?

I'm no expert on potatoes but:

This sounds like it might be some kind of gall. Potato wart comes to
mind too. (Synchritium Endobioticum).