My Dad was from Kansas, down near Ft. Scott. Here's what I think he might suggest. Get them in the ground. Slip the pot off. If there is lots of root development break it up. Plant them up to near the first leaf. Stake them. Cover for a few days if possible. I go round to produce stands and get freebie tall bushel baskets or what are called bean hampers someplaces. If this works OK if not let me know I will not try it myself. Steve in Baltimore County.

That won't help in this case as the tubers are already in the ground. They did not come as plants, rather as bare tubers. Thanks anyway

I can't tell you why it's happening, but when the shoot dies the tuber should send up a new one shortly. so, as far as that goes, all is not lost. Last year I had problems with wilting/death that was related to a rotting tuber, but the plant was a lot further along than what you are describing. Has it been really wet and cool? Rotting tubers could cause your problem I think. If you think that could be a problem, you could carefully dig one up just to check things out.

HTH
Katy

Well, there's two types of "brown" in my experience. There's the dark brown that to me means the plant is rotting, or the light brown which means its drying out.

Given your soil is clay, I'd say its probably the former, where the dark brown is almost black sometimes and rather than getting brittle, the leaves are wilting at the same time.

If this is the case, then my guess would be there is likely too much moisture at the ground surface (from the tuber to the air.) Of course the tuber could be rotting too.

I would definitely take the soil off the top of the tuber so you can check this out, whether the tubers rotting or not. It shouldn't be soft at all.

If I'm right, then you'll need to amend the soil some more to ensure the water drains away from the tuber.

Cheers,
Russ