Time to say goodbye to Rudbeckia goldsturm?
My Rudbeckia are now in their 3rd year. They are watered by a drip irrigation system, not sprinkled. The first year they bloomed well, last year they bloomed less but had dark spots all over their lower leaves which ascended thru the summer, and this year are afflicted with something new shown in the attached images. They are on the east side of our house so get a lot of morning sun but not much after noon. Can I help this year's problem? Should I consider replacing them with a better-suited flower in our foundation planting?
The history you've given and the photos lead me to believe the problem you have is septoria:
Mulching and drip irrigation are good practices, but perhaps you are correct that the site is not sunny enough for Rudbeckia. Other plants you might consider are daylilies, bleeding heart, astilbe, platycodon, hosta, columbine, coral bells, cranesbill, and many others.
A final thought: the damage showing in your photos also looks similar to four-lined plant bug damage. Given the history you've described, my guess would be septoria, but I thought I should mention this other possibility:
Thanks very much for your rapid response and very helpful recommendations. I'll follow up on them.