Alaska: What is destroying my Delphinium?

Greetings - It's a rare beautiful 55f day in Ketchikan. You should all be here!

I've attached a picture from last summer of a large, once prolific, Magic Fountains Delphinium. For the last 2-3 summers, the plant emerges as a healthy clump. The bloom stalks even look hopeful. As they grow taller the deformity appears - naked stalks with only the top blossom present. I see no evidence of any bugs no slugs.

Your help identifying the cause would be appreciated. Delphiniums usually do very well here. Thank you!

Marzette