Answer: Powdery mildew is a fungal disease that appears as a white powdery coating on the surface of the leaves. It looks like someone sprayed talcum powder over the entire plant. If your bee balm has this disease you can simply prune off the affected plant parts, even if that means cutting it down to ground level. It's hard to kill bee balm so if you do have to cut it way back, it should resprout within a couple of weeks. The new growth should be mildew free. Good luck with your bee balm.
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