Beat Cool-season Diseases with a Proven Agronomic Plan

Certain diseases thrive in cooler growing environments, so growers must remain vigilant even as temperatures start to drop. Along with regular scouting, having a preventive agronomic program in place with a rotation of products labeled for specific disease control is the best way to ensure diseases don’t threaten healthy crops.


Thriving in cool, humid environments, Botrytis, or gray mold, can impact crops from late fall into winter. It is particularly threatening to newly propagated material like germinated seedlings and unrooted cuttings. Post-harvest environments often create a moist, humid environment that can contribute to plant stress and lead to Botrytis.

Botrytis Gerbera
Botrytis sporulation on Gerbera daisy. Syngenta photo, 2016.

Initial infections result in water-soaked spots on foliage and flowers. Once established, gray mold can quickly spread throughout the crop and production area.

Rotating effective fungicides during production, like Mural®, Palladium® and Postiva®, and prior to storage and shipping helps ensure protection after crops leave production. Download our Botrytis rotation program for a full product recommendation schedule such as the one below.

Botryis Chart
*Foliar applications or excessive runoff of Palladium sprays may cause stunting or chlorosis to impatiens, New Guinea impatiens seedlings and some geranium varieties.

Downy Mildew

Another common disease to watch out for in the fall and winter is downy mildew. Recognizing early signs will help preserve plant quality and health. Leaf discoloration or spotting, often within the veins, are the most common initial symptoms. When the fungus invades the plant internally, stunting, distortion and mortality can occur.

When used in a rotation, Subdue Maxx®, Segovis®, Micora® and Mural fungicides provide excellent control of downy mildew. Since they each have different modes of action, these products create the framework for strong resistance management. Our downy mildew program includes rotation recommendations as well as scouting tips.


There are numerous Phytophthora spp. pathogens that can affect a wide range of herbaceous and woody ornamental plants in the nursery and landscape. They are responsible for causing root and stem rots, cankers, as well as foliar blights. While many prefer warm-to-high temperature conditions (70 – 90°F), others like Phytophthora ramorum thrive in cool-to-moderate temperatures (36 – 79°F, 68°F optimum).

Using a rotation of fungicides in different FRAC Groups, such as Segovis, Micora and Subdue Maxx helps prevent Phytophthora species in your operation. A preventive approach is essential for successfully controlling this disease because often it is too late to control once found. View our new Phytophthora solutions guide for a full product rotation schedule and more.

Phytophthora Foliar Aerial
Phytophthora on Rhododendron. Rechcigl, 2010.

Plan ahead to maximize savings

Make sure you have a plan in place and the appropriate products to protect against cool-season diseases for the rest of the year. Lock in your yearlong product rebates by making your qualifying purchases during the GreenTrust® 365 Early Order Period, now through Dec. 8. With the enhanced Double Up Bonus, Multipaks and more, you can get the best savings of the year on over 25 trusted brands.

See how the GreenTrust 365 Rebate Calculators can further maximize your savings at

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

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