Garden Pests and Diseases: Recurring problem with delphinium, 0 by LAS14

LAS14 wrote:
For several (many? I forget) years my delphinium plants have blackened. This can happen throughout the season and doesn't always affect the whole plant. But they are not thriving. I use a variety of fungicides, Safer, copper, funginex, etc. This year I've used mostly copper toward the end of the summer because that's what was in the sprayer for tomatoes for late blight. I have two widely separated beds for delphinium, and it affects both.

Often advice about fungicides says "read the label." But the label with detailed info is not accessible on lots of them unless you buy it first. Anyway, if I don't know what the problem is, I don't know what to look for on the label.

I acquired a digital camera mainly so I could post this problem. I hope someone can help. I love delphiniums!

In this first picture, the stems/leaves on the left have blackened. Those on the right are healthy.

TIA
LAS