Wasabi leaves drying up and dying
The leaves on my wasabi plant are progressively drying up and dying. I had the plant near a window with partial sun which may have led to its decline (too much light), but it's been out of the sun for a week in a spot with indirect light and has gotten worse since then. The dying leaves always initially have black spots on their stem, mostly near the leaf, which gets worse as the leaf dies. It's been very warm during the day (~80 F), but I would expect this to only cause some wilting, not die-off. Is this the result of too much light, or could it be fertilizer? I also haven't checked the roots yet for rot.
I'm hoping someone knows a bit about wasabi because there is very little information available online. It's not a very common plant to be grown outside of Japan and Washington state.
Young leaf emerging, potentially still healthy