subscribe
YouTube
Pinterest
Twitter
Facebook
Instagram
Search

How Do I Stop Powdery Mildew?

By: Jessie Keith

This zinnia has a severe case of powdery mildew.

“Every year I get white mold on the leaves of various plants in my vegetable garden. I don’t use any fertilizer or pesticide, other than an organic compost in the soil. It usually doesn’t cause a great deal of problems but is there something I could or should be doing?” Question from Lynda of West Warwick, Rhode Island

Answer: It sounds like you have powdery mildew, a common fungal infection that attacks leaves, causing white, powdery looking surfaces and blotches, particularly towards late summer. Some flowers and vegetables are more prone to it than others. For example, squash, melon, zinnia, and cosmos leaves typically develop powdery mildew, unless you have chosen mildew-resistant varieties.

The disease acts on leaf surfaces, disabling a plant’s ability to respire and gather sunlight. This weakens them and reduces productivity. Severe cases will kill plants. Here are four things that will stop or reduce the disease.

1. Choose powdery-mildew resistant varieties. Before buying a garden flower or vegetable that typically gets this disease, search for resistant varieties. Choosing vigorous, highly disease-resistant varieties will always result in a happier garden. You can often find lists of resistant varieties at university websites, like Cornell University (click here to view).

2. Provide plenty of sun, water, and airflow. Take good care of your plants and give them lots of sun and air, two things that discourage mildew development. Refrain from planting too closely together.

3. Remove diseased leaves as you see them. Simply prune off bad leaves on sight. Be sure to clean your pruners well after cutting any diseased plant.

4. Apply an organic fungicide. The all-natural product, Green Cure, stops powdery mildew. Apply it when you first see any signs to stop the disease in its tracks.

I hope that this information helps!

Happy gardening,

Jessie Keith

Black Gold Horticulturist

 

About Jessie Keith


Plants are the lens Jessie views the world through because they’re all-sustaining. (“They feed, clothe, house and heal us. They produce the air we breathe and even make us smell pretty.”) She’s a garden writer and photographer with degrees in both horticulture and plant biology from Purdue and Michigan State Universities. Her degrees were bolstered by internships at Longwood Gardens and the American Horticultural Society. She has since worked for many horticultural institutions and companies and now manages communications for Sun Gro Horticulture, the parent company of Black Gold. Her joy is sharing all things green and lovely with her two daughters.

Leave a Reply

Content Disclaimer:

This site may contain content (including images and articles) as well as advice, opinions and statements presented by third parties. Sun Gro does not review these materials for accuracy or reliability and does not endorse the advice, opinions, or statements that may be contained in them. Sun Gro also does not review the materials to determine if they infringe the copyright or other rights of others. These materials are available only for informational purposes and are presented “as is” without warranty of any kind, express or implied, including without limitation warranties of merchantability, fitness for a particular purpose, and non-infringement. Reliance upon any such opinion, advice, statement or other information is at your own risk. In no event shall Sun Gro Horticulture Distribution, Inc. or any of its affiliates be liable to you for any inaccuracy, error, omission, fact, infringement and the like, resulting from your use of these materials, regardless of cause, or for any damages resulting there from.

While we have made every effort to ensure the information on this website is reliable, Sun Gro Horticulture is not responsible for any errors or omissions, or for the results obtained from the use of this information. All information in this site is provided “as is”, with no guarantee of completeness, accuracy, timeliness or of the results obtained from the use of this information.

Use of this site is subject to express terms of use. By using this site, you agree to our Terms of Use

View Our Privacy Policy