At the end of February I put down some red mulch around my roses. But now I have a Nasberry tree that is starting to shed its leaves. I was wondering if it is Ok to leave this on the ground around the roses. Of course it doesn't look quite to as nice as the mulch, but is it helping to make better dirt here in my sandy soil?

I here some people say we should pick up all of the leaves around the roses, because it causes the rose to be more prone to black spot and other things. And I hear other people use leaves as mulch.

Thanks for any input