Protecting Plants from Powdery Mildew During Production

Healthy plants are crucial for a successful operation, which means protecting them from ornamental diseases from day one. Before you begin production, be prepared with tools to ensure healthy plants, including proper scouting methods, cultural practices and products that offer comprehensive, long lasting disease management. While there are many diseases that can threaten your operation, one of the most common is powdery mildew as it can affect a wide range of herbaceous and woody ornamental crops.

Identifying Powdery Mildew

When scouting for powdery mildew, look for white, talcum-like spots called “colonies.” If left unchecked, the spots will eventually increase in size and number to cover the plant’s surface.

Powdery mildew fungi thrive in temperatures between 62° – 72° F and when relative humidity is 70 percent or greater. It can be more serious on woody ornamentals such as roses and crape myrtles because it attacks new growth, including buds, shoots, flowers and leaves.

Proper Cultural Practices

It’s crucial to identify diseases early in the production process and to implement proper cultural practices and preventive fungicide applications. Without preventive strategies, you may need to resort to curative applications, which are costly and often less successful.

Follow these cultural practices as the first step toward powdery mildew prevention:

  • Reduce relative humidity around foliage by heating and venting as needed
  • Overhead irrigation may reduce the spread of powdery mildew as it washes spores off plants
  • Regularly inspect new propagation material for signs of infection

Proven Products

Pair your cultural practices with preventive applications of trusted products used to fight powdery mildew infections.

Postiva™, Mural® and Palladium® fungicides provide excellent control of powdery mildew and are strong rotation partners for a powdery mildew prevention program throughout production. Prior to disease development, apply fungicides in a rotation on a 14-day interval. For active infections, shorten the application interval to seven days.

Control of Powdery Mildew on Gerbera Daisy with Postiva

Flowers treated with Postiva Postiva 10 fl. oz.
Untreated flowers Control
2018 – Krasnow, Vero Beach Research Center

Featuring ADEPIDYN® technology (pydiflumetofen) and difenoconazole, Postiva is the latest fungicide innovation to fight powdery mildew with systemic activity. With foliar spray applications, the petiole and apical bud of plants absorb the product, resulting in the upward systemic movement of the two active ingredients, protecting new tissue as shown in the photos below. This allows for strong, disease-free growth in plants.

Carbon-14 comparison 2017 – Jealotts Hill, Syngenta

Learn more about trusted solutions for powdery mildew by downloading our complete Powdery Mildew Rotation Program.


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.

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

© 2022 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. ADEPIDYN®, Mural®, Palladium®, Postiva® and the Syngenta logo are trademarks of a Syngenta Group Company.

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