Regalia - A new fungicide for organic and conventional disease control

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

Regalia is a new fungicide for grapes and berry crops (blueberry, raspberry, blackberry, strawberry) with a different mode of action from most other fungicides. It is made with an extract from the plant Reynoutria sachalinensis (giant knotweed), which when sprayed on plants, activates natural plant defenses. This induced diseased resistance is not systemic (i.e., only treated green leaf area is protected), but there is a translaminar effect. This means that when the product is sprayed on the top of a leaf, the bottom of that leaf also is protected. New plant growth is not protected – therefore the product needs to be reapplied on a seven to 14-day schedule. The resistance induction takes one to two days and light is required. Therefore, Regalia should be used as a preventative treatment. The product should be shaken well prior to use as there are solids in the extract. Use a 50-mesh or larger nozzle screen. The addition of a wetting agent is recommended.

Regalia can be tank-mixed with other fungicides to enhance control. Regalia can also be alternated with other effective fungicides in an IPM program for fungicide resistance management. The use rate is 0.5-1 percent (or 2-4 qt in 50-100 gallons of water) when applied alone or 1-4 qt per acre when tank-mixed with other fungicides. Regalia is listed by the Organic Materials Review Institute, which means that it is suitable for organic crop production.

In small plot field trials in Michigan, Regalia had moderate to good activity against grape powdery mildew and Botrytis bunch rot in trials with an older formulation. Regalia (applied with Nu-Film-P, a spreader-sticker) provided moderate to good control of mummy berry and fair control of anthracnose in blueberries in 2009 trials. Additional trials are underway. The Regalia label can be viewed on the following website ( by looking under “Services”, then “Labels/MSDS.” The price of Regalia is about $15 per quart. The restricted entry interval is four hours and the pre-harvest interval is zero days.

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