Powdery Mildew in California Grapes

Powdery mildew is a fungal disease that can affect a variety of plants.  Grape powdery mildew (Erisiphe necator, syn. Uncinula necator)  is the most significant disease in terms of expenses for control and losses in quality and yield faced by grape growers in California, as well as worldwide.  Powdery mildew management accounts for 74 percent of total pesticide applications by California grape growers and a 17 percent of total pesticide use in California agriculture (by weight of active ingredient). The pecuniary costs to the growers, which include the costs of purchasing and applying fungicides, are typically in the range of 3–7 percent of the gross value of production in places where powdery mildew pressure is significant. Various efforts to improve powdery mildew control methods range from development and testing of new powdery mildew control products and methods for forecasting powdery mildew pressure to development of new grapevines resistant to powdery mildew. Economic studies of powdery mildew management with collaboration of the Center for Wine Economics include:

Analysis of the total costs of powdery mildew management and the economic value of grape varieties resistant to powdery mildew. Conducted as a part of the VitisGen project. Publications include:

The Value of Powdery Mildew Resistance in Grapes: Evidence from California

The Costs of Powdery Mildew in Grapes.

Economics of Powdery Mildew Forecasting and the use of the Powdery Mildew Index. Publications include:

Behavioral Responses to Disease Forecasts: From Precision to Automation in Powdery Mildew Management

Multi-Dimensional Responses to Risk Information: How do Winegrape Growers Respond to Disease Forecasting and to What Environmental Effect?

California Wine Grape Growers’ Use of Powdery Mildew Forecasts

For further questions, please contact the following research collaborators:

Julian Alston

Kate Fuller

Travis Lybbert

Olena Sambucci

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