Answer: It's difficult to diagnose a problem without actually seeing it, but you might be dealing with a disease called Botrytis. Botrytis attacks blooms and canes of established plants, and the bare roots of improperly stored or shipped plants. It appears as a gray-brown fuzzy mold. Buds may fail to open or open only partially. A gray-black lesion usually appears on one side, extending from the bottom of the bud down the bloom stem. On partially opened blooms, petal edges may appear brown and soft, an appearance similar to larval thrips damage or "balling."
Botrytis fungal spores favor continued wet weather and darkened conditions.When symptoms first appear, remove
blooms and bloom stems as soon as possible to reduce spore proliferation. If fungicides are selected, those commonly used for Blackspot will suffice for control. However, smart cultural practices will do much towards control. Plant roses where they will receive early morning sun, thus drying blooms and buds of dew.
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