How to Control Powdery Mildew

how to control powdery mildew
How to Control Powdery Mildew

What is Powdery Mildew?

Powdery Mildew is an easily identifiable fungal plant disease which unfortunately for home gardeners, is quite common! It has a tendency to plague ornamental trees and shrubs, rose gardens and yes, even vegetable gardens. Take heart, there is a relatively simple, inexpensive fix. . .

First, identify the problem… the leaves of the affected plants will appear to have white (or gray) powdery spots on the leaves (or stems, flowers, and fruits!). (See the leaves in the photo of this affected zucchini plant). The foliage of the plant may have yellowed significantly or even started to turn brown.

How to Control Powdery Mildew

The good news is that Powdery Mildew doesn’t usually kill the plant, the bad news is, it can cause the leaves to fall off or prevent the plant from producing additional fruit.

What Causes it to Form?

Powdery Mildew generally forms on plants during periods of High Humidity, low light, and moderate temperatures. You can help prevent it by ensuring your plants have plenty of air circulation around them, 6+ hours of sunlight each day and using slow-release fertilizers. It also helps to avoid Over-fertilizing the plants as well.

How to Control Powdery Mildew
Powdery Mildew on Lilac Shrub via Laidback Gardener

Here’s the simple fix

You’ll need 1-2 tsp of Plain baking soda to about 1 1/2 cups of water. Dissolve the baking soda in a small spray bottle with water, seal, shake well and apply liberally to the dry leaves of the affected plants.

Repeat the application after rain. The baking soda changes the ph level of the plants’ leaves and stems creating an unstable environment for mildew spores; thereby preventing them from reproducing and spreading.

This method can be used as a preventative measure if you have a tendency to have issues with powdery mildew. After all, as grandma used to say, “an ounce of prevention is worth a pound of Cure”!

© Can Stock Photo Inc. / ArtPhaneuf

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About Liss 4191 Articles
Melissa Burnell, known to her friends and fans as "Liss," grew up in Southern Maine, now residing in sunny South Carolina. As a busy Wife, Mother of two sons, an avid photographer, and self-employed entrepreneur, Liss understands the value of both time and money.


    • Thanks for this article! The lilacs are really looking bad this year. I appreciate learning something to do with them!

  1. Absolutely love this baking soda trick!! I recently helped write an article about powdery mildew for Safer Brand and we mentioned it in our list of ways to prevent powdery mildew 🙂

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