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What Is the Remedy for Mildew on a Bee Balm Bush?

By Barbara Fahs ; Updated September 21, 2017

Bee balm is the common name for a fragrant flowering plant in the Monarda genus. Also called bergamot and Oswego tea, it was the plant the American colonists used when they stopped using black tea in protest of British taxation. In addition to having a pleasant taste, this herb has been used to treat colds and sore throats. It’s a small, attractive plant with red flowers, which attract butterflies, bees and hummingbirds. But it can develop powdery mildew. When this happens, you can stop the mildew's spread with several simple remedies.

Grow your bee balm plant in soil that is moist, slightly acidic and rich with organic materials to keep it healthy and better able to resist plant diseases such as powdery mildew. Bee balm also thrives in areas that have partial shade to full sun.

Spray your bee balm with a combination of milk and water once each week if you notice a fuzzy white or gray coating on the leaves, stems or flowers. Stir 1/2 cup milk, either skim or whole, into 1 gallon of water and then drench your plant thoroughly. The milk and water spray works, according to online resource Pioneer Thinking, because the lactobacillus in the milk will grow on the leaves, leaving no opportunity for mildew spores to gain a foothold.

Spray your plant with a purchased fungicide, such as one with potassium bicarbonate. You must use fungicides before the mildew appears or as soon as you notice it because they do not normally succeed in getting rid of established mildew.

Keep the growing area cleaned up of leaves and other plant parts that have fallen due to powdery mildew. Burn or discard debris in the fall to prevent further outbreaks of this disease. Do not add diseased plant parts to your compost pile.

 

Things You Will Need

  • Milk
  • Water
  • Commercial fungicide

Tips

  • Although this plant prefers moist soil, mildew is more likely to occur when its leaves get wet. Water it from below by setting a hose at its base and running it at a slow drip.
  • To avoid the problems powdery mildew can cause, select a cultivar that has been shown to resist this disease. Examples of resistant species include 'Violet Queen,' 'Marshall's Delight,' 'Gardenview Scarlet' and 'Stone's Throw Pink,' according to studies conducted by the University of Vermont.
  • Plant your bee balm plants far enough from each other to allow good air circulation, which will help prevent powdery mildew.
  • Examples of effective commercial fungicidal products include myclobutanil (Eagle) and triadimefon (Bayleton or Strike).

Warnings

  • Do not use more than 1 part milk to 9 parts water because if the milk content is higher than 30 percent, it will cause another fungus to grow on your plant.
  • The University of Vermont reported that their studies showed that sulfur, neem oil and baking soda are ineffective mildew treatments for bee balm plants.

About the Author

 

Barbara Fahs lives on Hawaii island, where she has created Hi'iaka's Healing Herb Garden. Fahs wrote "Super Simple Guide to Creating Hawaiian Gardens" and has been a professional writer since 1984. She contributes to "Big Island Weekly," "Ke Ola" magazine and various websites. She earned her Bachelor of Arts at University of California, Santa Barbara and her Master of Arts from San Jose State University.