I haven't actually ever grown them myself, but as I understand it they are supposed to be harvested in the fall and stored in something like damp sawdust. Then new tubers (or some of your own stored tubers) are replanted in the spring. The tubers can rot in very wet ground, so probably the spring snowmelt and cold wet ground let to some spoilage?

You're probably right; I'll just wait until late summer/fall before attempting to harvest more tubers.

Think I experienced the the same thing after several years of
growing them long time ago, ...always left some in the ground after harvest.
Yes, storing them might me better.
We used to pickle them...I loved them allot, perhaps I should start again, not sure where I can find tubers, I think we ordered from a catalog.

They look nice too...about 6 feet high and yellow flowers, like
little sunflower heads.

Oops, I just posted a question about sunchokes.