We recently planted several knockout roses and have now discovered that some of the buds had turned brown and were drooped over. The plants look very healthy otherwise. Could you give us some indication of what the problem might be?

Gardens & Landscapes April 21, 2011 Print Friendly and PDF
Roses often have a number of insects and disease issues that cause wilted brown buds, so it is difficult to give you a definitive diagnosis. Some of the possibilities are insects or disease. Thrips are minute (one-sixteenth of an inch) insects that attack rose buds in their early stages. Rose blossoms turn brown and buds open only partially. The brown edges of the petals appear to stick together. Remove and destroy all infested blooms and buds. You may want to refer to the North Carolina State University publication: Flower Thrips. Botrytis blight, Botrytis cinerea, causes the buds to turn brown and decay instead of opening. Buds may also have a gray mold. The fungus is most active when temperatures are 62°F to 72°F and conditions are moist. Avoid problems with good garden sanitation. Pick up leaves and fallen blossoms so the fungus will not have a chance to produce large quantities of spores. Keep the foliage as dry as possible. Fungicides also can help. Refer to the following University of Minnesota publication: Rose Diseases.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.