Knowledgebase

Treating indoor begonia powdery mildew #753228

Asked June 01, 2021, 11:34 AM EDT

Good morning, I have an indoor begonia that appears to be beset with white powdery mildew. I've had the begonia for about a year and noticed this about 6 months back and have sprayed it several times with Garden Safe Fungicide 3 (active ingredient Clarified Hydrophobic Extract of Neem Oil 09%, Other Ingredients 99.1%), but the white powdery mildew continues. The plant has set alongside other plants in the window that are not begonias and no other plant shows any signs of the powdery mildew. Would love to find a way to treat this one to keep it. Thank you.

District of Columbia County District of Columbia

Expert Response

Hi, Devin,

You can read about powdery mildew on indoor plants by clicking here. You will see that the two prevention strategies are:

Any method that will lower the humidity, or increase air circulation will help to lessen the chances of infection.

Space plants so that air can circulate between them to help reduce moisture.

Since you have already tried a fungicide unsuccessfully, you might try spraying with a solution of baking soda, mild dish soap and water. The proportions are 1 to 3 tablespoons of baking soda and 1/2 a teaspoon of dish soap to a gallon of water. Baking Soda works by creating an alkaline environment on the leaf, and fungus (powdery mildew and blight are both fungi) cannot colonize the surface of the leaf since they need a neutral pH (around 7.0) to survive and thrive.

Thank you for your question.

Barbara

Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For more information on a variety of yard and garden topics, visit the HGIC website and our blog, Maryland Grows. Replied June 02, 2021, 1:46 PM EDT

Loading ...