I forgot to mention my own experience with the rose Julia Child last season.
Twenty feet away lived Westminster Cathedral and Golden Celebration. WC, I have reason to believe, fell prey to black spot early on and turned out to be a very effective generator of the spores, infecting Golden Celebration, Winter Sunset, and Julia Child. The infection was light. Most leaves were infected, but unlike Winter Sunset which spent the rest of the season defoliated, there was almost no defoliation. I should mention that Caramella FT which is a little closer to WC was lightly touched with BS, too.
In March through June we enjoy 20% humidity, but when the monsoons blow in, the humidity can hover above 50% for weeks in a row in July and August. This is when blackspot struck last year. Winchester Cathedral has been moved more than 100 yards away, and I've sprayed a few times this season with Actinovate. In eight or twelve weeks I'll find out whether it made a difference. Point is: any rose that suffers from black spot in Arizona must be planted with some reservations by anyone where the disease is rampant.
