Answer: It might be that your new roses have a disease called black spot. It is a common rose disease and some plants are more susceptible to the problem than others which would explain why your current roses are healthy and the new ones have the disease. Black spot is one of the most common diseases of roses. Fungicides will help control it, but you'll need to practice good garden sanitation (prune and remove the most obviously infected canes), and try to keep water off the leaves. Fungicides need to be applied every 7-14 days during the growing season. Some choices include Funginex, Daconil, Captan, Rose Defense, or Bravo. You'll find others in the garden section of your local Home Depot. I'm afraid black spot is just one of the challenges you'll face when growing roses, but the reward is worth the effort. I don't think there's anything quite as lovely as a garden filled with roses! Best wishes with your roses.
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