Tips for Preventing Powdery Mildew

Powdery mildew is one of the most common diseases that affects a wide range of herbaceous and woody ornamental crops particularly in late spring to early summer. Before you begin production, make sure you have the proper cultural practices and products in place to help prevent powdery mildew outbreaks.


Powdery mildew fungi form white, talcum-like spots called “colonies” on leaves, stems and flowers. Over time, these colonies increase in size and number to cover the plant’s surface.

If not controlled, severe infections will cause leaves to turn yellow, brown and then drop, resulting in reduced plant vigor and growth. While powdery mildew is often first observed on the upper surface of the leaves, both sides may develop colonies, so it is important to check both sides of the leaf when scouting.

Powdery mildew on Gerbera, Rechcigl

Environmental factors

Next, make sure the environment within is not conducive to powdery mildew by:

  • Reducing relative humidity around foliage by heating and venting as needed
  • Adding overhead irrigation, which may reduce the spread of powdery mildew as it washes spores off plants
  • Regularly inspecting new propagation material for signs of infection

After implementing proper cultural practices in your operation, it is important to have an agronomic plan in place to prevent disease development. An agronomic plan will provide a framework for rotating products labeled for powdery mildew control, such as Mural® and Postiva™ fungicides.

Mural is powered by two active ingredients – SOLATENOL® technology, an advanced generation SDHI, and azoxystrobin, a systemic, broad-spectrum strobilurin fungicide. It provides flexible control of a wide range ornamental diseases including powdery mildew, at low use rates.

Postiva, the latest addition to the Syngenta fungicide portfolio, features a combination unique to the ornamental market in FRAC Groups 7 and 3. It is rapidly absorbed into plant tissue creating a rainfast barrier of protection, preventing infection and disease progression.

Learn more about incorporating these products into an agronomic program with this powdery mildew rotation program.

All photos are either the property of Syngenta or are used with permission.

Performance assessments are based upon results or analysis of public information, field observations, and/or internal Syngenta evaluations. Trials reflect treatment rates commonly recommended in the marketplace.

© 2024 Syngenta. Important: Always read and follow label instructions. Some products may not be registered for sale or use in all states or counties and/or may have state-specific use requirements. Please check with your local extension service to ensure registration and proper use. Banner Maxx®, Mural®, Postiva™, SOLATENOL® and the Syngenta logo are trademarks of a Syngenta Group Company. All other trademarks are the property of their respective third-party owners.

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