The Pecuniary and Nonpecuniary Costs of Powdery Mildew and the Potential Value of Resistant Grape Varieties in California

Abstract

Powdery mildew (PM) is the most expensive grape disease to control and causes the greatest losses in quality and yield worldwide. Grape varieties resistant to PM are being developed, but the value of such varieties to growers in different industry segments is not yet determined. Barriers to adoption of new varieties vary by industry segment and are likely to affect the total potential benefit realized by growers. The first step in estimating the potential value of PM-resistant varieties is to establish the costs of PM management that these varieties will mitigate for each major segment of the grapegrowing industry. We used Pesticide Use Reports from the California Department of Pesticide Regulation, data on pesticide application costs, and measures of environmental impact to evaluate the pecuniary and nonpecuniary costs of managing PM in California grape production. We estimate the statewide cost of PM management in 2015 at ~$239 million, of which $176 million was borne by growers of winegrapes. In addition, PM management accounted for 89% of restricted material (pesticide) applications by grapegrowers, so eliminating PM would reduce the environmental burden from disease management in grapes significantly. Using choice experiments, we evaluated the preferences of individual growers for specific varietal traits and found that winegrape growers place a high value on both the varietal name and the savings in costs from reduced application of fungicides. We conclude by discussing possible adoption scenarios for resistant varieties and the resulting benefits to the industry.