Spinach turning yellow

I had thought that with this cold wet spring, at least I would be getting a nice crop of spinach. But no. My spinach has sprouted well enough, but the plants aren't growing vigorously. Instead, they are stunted and turning yellow, beginning with the cotelydons, then the outer leaves.

I've been growing a new variety, Space, this year and wonder if that has anything to do with the problem. Nearby lettuce is doing fine.

Here is a picture

What did you fertilize with?

BB

Could it be a disease? I lost my whole spinach bed last year from something similar. It also affected my beets to a lesser degree, but didn't touch the turnips or any other greens. After searching around on line, I decided it must have been stemphylium botryosum. In March I had a crop of volunteer spinach pop up maybe 30 feet away from where it was last year, and it seemed to be fine. I harvested it all before it had many big mature leaves, though, so I don't know if it would have been affected.

This spring - fertilized with Garden-Tone, plus about a cup of dried blood for the row.