What causes the stems of sunchokes to turn red and lower leaves to die?

Question

The bottom leaves of my sunchokes are beginning to die in tall grass, and a reddish color (with a small bubble that looks like a boil from the long stems that come out) is going up the main stem on one of the plants.

Does that mean I should dig them up, cut back on the water, or something else?

finally was able to get some images of it from someone:

Answer 1

Harvest when all the leaves have died back and after your first frost as that makes them sweeter. I left mine in the ground until I needed them which was late autumn, but some people leave them in the ground in winter as well. They'll keep better in the ground then out.