I can never decide this myself, lol! I usually do treat if its in a client's garden, specially as I may not be there collecting the fallen leaves - but never bother at this time of year in my own, relying instead on, as you say, collecting up the fallen leaves later, because they'll be naked soon anyway. So, up to you really.

I sprayed mine a few weeks ago, what a difference it made in just a couple of days, so I would say yes. Mine have now stared to flower again.

Thanks, guys. We are due for some warm weather in the next few days. It will be interesting to see if this stresses the plant and causes leaf drop.

I have sprayed mine in the last week as I do think it reduces it spreading in September.

It is almost impossible to do a perfect cleanup of the dead leaves. I would spray to eliminate spore sources on the leaves you might miss.

What Tugbrethil has said is why I always do my clients' roses - but clearly am too lazy to do the ones in this garden where I live...

Hmmm, I may just spray to be safe.