Thanks for writing. Are your roses growing in full sun? If not, i'd guess that's the problem --- the stems are stretching trying to find more light. Growing them in full sun should help.
Do they start out with more foliage but then drop it? There are a number of rose diseases that cause old leaves to discolor and fall off.
Do you prune them? Cutting your roses back to a foot tall in early spring will help encourage them to be lush and full instead of tall and lanky.
---Justin, Senior Garden Editor, BHG.com