Lyn, please don't take this the wrong way but no, that actually did not answer my question. I did have a quick look at that link but to tell you the truth, I have a slight aversion to those articles, no offence to the authors, but I would rather hear about your personal experiences than read some long article.

Anyway, I did know that bs spores over-winter in old mulch, the infected fallen leaves and even on the stems. That is why I try to eradicate all possible sources of infection which include continual removal of the fallen leaves during the season, the removal of mulch during my winter clean up and dormant spraying before the roses leaf out in spring.

Maybe I didn't express myself clearly enough. I wanted to know if NOT putting on a new mulch layer this spring could have contributed to the increased black spot I experienced this year.
In other words, my question again:

Does a NEW mulch layer in spring, after dormant spraying, help to reduce the spread of black spot?

My logic says yes but I wanted to hear other opinions.

Sharlene, your thinking sounds logical to me but I have no direct experience; I just expect blackspot here in the spring and fall regardless.

I didn't mulch this year either and plan to start mulching again, hopefully this fall/winter. It seems there was more blackspot this year, but it was so muggy and rainy most of the summer I'm not sure which would have attributed most to it. Does make me wonder if soil splashing onto the plants during heavy rain is a factor, sort of like tomato blight.

Neal, exactly my reasoning. I will be mulching again but only in spring.

Why do you wait till spring?

I like to mulch after the ground has frozen to deter burrowing rodents and help prevent heaving, especially with bearded irises. But that often doesn't work out because some winters the soil never really freezes. At least if I do it after the soil has cooled, bulbs and other plants are less likely to sprout during winter mild spells.

Sharlene ...

No offense taken ... it was that one paragraph that was of interest to me. I had thought that once the spores died, it was a non-issue, and never bothered with the winter clean up.

When I discussed this with Kim and others it seems like the general answer is that the spores are in the air and if the conditions are right and the rose is susceptible, there really is not much you can do to reduce bs infection other than your best garden practices. It always depends on the rose and the location of the rose.

I have had personal experience of hard pruning a rose into susceptibility .. There are some roses that simply do not like a hard prune and seem to almost sulk and get every disease known to roses, but if left alone are always healthy and happy roses. Can I tell you which ones ? No. That's because our climates and situations are very different.

We already know that stressed roses are more disease prone ... so that's a given, too, but that's not what you are asking.

Neal, I do 'heap' some of my roses with compost to help protect them over winter but usually only put the proper mulch layer on in spring after I have done my dormant spraying. Lime Sulphur is supposed to kill the spores on the surface of the soil. I say supposed to because I did spray last spring but it didn't really help much this year but then I didn't mulch ....
BTW, I have never mulched my iris - wondering if I should?

Ah, that makes sense Although it goes against conventional wisdom to mulch bearded irises (unless you're in an arid climate), I feel like I have better results when I mulch. I'm careful not to cover rhizomes and apply mulch around the outside of clumps.

Many of my new irises rotted this spring when I couldn't get the mulch off them fast enough when the rains came pouring down.
It was my fault for planting the iris in the rose bed. We dumped loads of mulch on the roses and I didn't get it spread correctly and some iris were completely covered. I won't make that mistake again!