Baking Soda Spray for Powdery Mildew

Repeat the application as needed.

Powdery mildew is a common fungal disease that occurs when plants grow too close to one another and lack air circulation. The buildup of humidity among the plants is ideal for the fungal spores' germination. If you notice a white or gray powdery substance on your plant's foliage, suspect powdery mildew. Baking soda, also called sodium bicarbonate, sprays have been used as a garden fungicide for quite some time, according to scientists with Cornell University. Author Alfred C. Hottes, in a book he published in 1933, suggested a spray composed of baking soda and water to treat fungal diseases on roses.

Things You'll Need

• Baking soda
• Horticultural oil
• Spray bottle

Instructions

1. Combine 1 tbsp. of baking soda and 2.5 tbsp. of horticultural oil in 1 gallon of water.

2. Pour the mixture into a spray bottle. Store any leftovers in a closed container, out of the reach of children.

3. Spray the infected portions of the plant until they are dripping with the spray. You may need to shake the bottle continually while spraying to keep the mixture from separating.

4. Repeat the application in one week, if necessary.

Tips & Warnings

• To avoid burning the foliage, spray the baking soda fungicide early in the morning or after sundown.

• Scientists at Colorado State University are still using this mixture experimentally. They suggest that you use it at your own risk.

References

• Cornell University: Material Fact Sheets-Bicarbonate (Potassium and Sodium)
• Colorado State University Extension: Powdery Mildews