Roses – Black Spot Disease

Q: My best rose came down with black spot disease. I removed all damaged leaves and sprayed it but overnight it was on other leaves! 

A: You need to start alternating fungicides. When you use one product exclusively, black spot fungi develop resistance to it. You’ll need to become adept at reading pesticide ingredient labels.
Look for tebuconazole, propiconazole, chlorothalonil, and myclobutanil, purchasing three of them. You should swap chemicals after every two applications. To further prevent black spot on susceptible roses be sure to replace their mulch every fall and avoid overhead irrigation.

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