I grow Super Sugar Snap peas in large containers every year, and every year I see the same thing -- around the time they flower, they start dying from the bottom up. This happens quite early -- the attached photo is of the stage where the first peas are starting to appear on the vines. I can still harvest from the plants as the tops are still healthy-looking, but they're gradually dying and will stop producing pretty soon.
Is this part of a normal life cycle for this variety of peas, or is something wrong?