You can prune your roses lightly by one fourth or less in the fall but wait until spring do a heavy pruning as cutting back plants can stimulate growth and you want your roses to slip into dormancy before the cold. You can however remove all the leaves and send those diseased things out with the trash. Rake all fallen leaves from the ground so as not to spread the spores of disease. Good air circulation, sun and feeding your roses in spring and summer will help them fight disease next year. Keep growing, Marianne Binetti