Sorry I don't know the answer to your question, but all my roses suffered
from spotted or black leaf problems for several years. Last fall I dug them
all up and transplanted them in full sun, with a lot of space between them
to improve the air flow. I also prune the centers out of them to allow for
more air circulation. This year they were the healthiest looking that they
have ever been, and as long as I keep cutting off the blooms when they
started looking bad, they continue to set on new blooms.

The news group rec.gardens.roses might be able to give you the information
you are looking for.
Have you ever tried them?

Dwayne

"Robert" wrote in message
...
Can I have suggestions for the most disease resistant bush/ht type rose
please? Thanks