Sodium Bicarbonate

• Sodium bicarbonate (NaHCO3) is also known as baking soda. Commonly used for baking and cleaning purposes, it has been demonstrated to have antifungal properties.
  
  

As a Fungicide

• According to the National Sustainable Agriculture Information Service, baking soda has been used to treat plants for fungus problems since the early 20th century. Plants such as roses and tobacco as well as grapes and varieties of cucumber have all benefited.
  
  

How to Apply It

• According to OISAT, you can mix baking soda with horticultural oil, liquid dish soap, or vegetable oil, and water, to create a liquid for spraying on plants. Fill a sprayer with your mixture and thoroughly wet the plant, including the undersides of leaves. Apply your baking soda solution for fungus as soon as symptoms appear, and reapply every 2 weeks thereafter.
  
  

What Kinds of Plants Will Benefit

• Any plant that is affected by powdery mildew or blackspot can benefit from a fungicidal application of sodium bicarbonate. It is safe for edible as well as ornamental plants.
  
  

Precautions

• Harvest any mature fruits or vegetables before you spray, and apply baking soda spray early in the morning or later in the afternoon. Keep the mixture out of the reach of children and pets, and do a test application on one or two plants first.