Answer: Water stress can cause the leaves to dry up, as can residuals if you've recently sprayed chemicals on your roses. Fungal diseases can also cause the leaves to dry up. I can't really diagnose the problem without inspecting your rose bush. Why not clip an affected stem with leaves and place it in a plastic baggie? Take it to your local cooperative extension office or well staffed nursery for help with diagnosis. Helpful folks there can suggest controls or remedies for the problem. Best wishes with your roses.
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