Bee balm, known botanically as Monarda didyma and commonly as wild bergamot, is a summer flowering perennial that thrives in full sun and dry soil conditions. When exposed to conditions at odds with its basic requirements, such as overly-wet soils, high ambient humidity or protracted cloudy, rainy weather, bee balm is susceptible to gray mold. While not always deadly to the plant, mold can be unsightly, deforming and killing portions of plant tissue.
Scale back on watering so the top few inches of soil becomes dry before watering again. Water at the soil line, never over the top of the plant. Be careful not to splash water onto the leaves and stems of your bee balm.
Cut away the mold-damaged stems and flowers, burning or otherwise discarding the cuttings to prevent the spread of the disease.
Clear away the surface of the soil surrounding your infected bee balm plant. Any leaves, flower petals, trash or dropped plant clippings can serve as a breeding ground for mold spores.