Answer: The symptoms you describe may be just a result of late fall fertilizing and very fast spring growth. When stems get the message to grow in a hurry, the growth can be thin and unable to support the weight of the buds. Or, it could be a symptom of Botrytis. Botrytis Blight is caused by the fungus Botrytis cinerea. The disease causes flower buds to droop and remain closed. Buds turn brown and decay. Sometimes partially opened buds are attacked, and an entire flower may be covered by gray fungus. Watch your roses for these signs; if present, treat as necessary.
Symptoms: A smooth, slightly sunken, grayish-black lesion may develop just below the flower head. The bud is destroyed. It frequently hangs over at or near the lesion. The fungus may also infect stub ends of stems from which flowers have been cut.
Disease Cycle: Botrytis is a gray fungus that generally lives on dying tissue. With the right conditions, any dead plant tissue can release thousands of Botrytis spores. Botrytis infection occurs when water remains on leaves or buds.
Control: Cut and destroy all infected blossoms as soon as they droop or die. To prevent large numbers of fungal spores, remove dead plant material on which spores are produced. Fungicide application may be necessary.
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