Assessment of UV-C Radiation as an Integrative Pest Management Tool for the Management of Grape Powdery Mildew and Botrytis Bunch Rot

View the project final report

Commodities

• Fruits: grapes

Practices

• Education and Training: demonstration
• Pest Management: chemical control, integrated pest management

Management of grape powdery mildew requires great financial, environmental, and public health costs due to a heavy reliance on fungicides (~89% of the fungicide active ingredient used in grape production). New pest management tools are needed to reduce the environmental effects of heavy fungicide use and mitigate the emergence and spread of fungicide resistance. Germicidal ultraviolet C light (UV-C) may provide a new management tool for the improved control of powdery mildew in grapes that addresses these goals. Our research has shown that powdery mildew isolates vary in their tolerance to UV-C, but the effective doses are within ranges that can be reached in field applications. Small plot research trials demonstrated that UV-C significantly reduces disease development with or without augmentation of fungicides and without impacting fruit quality. Although treatments of UV-C alone exceeded commercially acceptable disease levels, it is likely this is an artifact of plot-to-plot interference from the untreated controls. It is possible that the UV-C applications will be more effective in a commercial setting where disease pressure is lower and more realistic. This technology needs to be tested at a commercial scale and compared to current management practices. However, this is not likely to occur until autonomous application technology (e.g., self-driving devices) reaches the robustness required for long-term field use. Finally, research results and live demonstrations of the UV-C application arrays have been made in commercial vineyards at various grower and researcher meetings serving Oregon, Washington, and California. Virtual and in-person research presentations and demos were well attended and accounted for both growers, researchers, and other agricultural professionals. Survey results show a high level of knowledge gained at events by growers who participated in the survey, and at least eight growers immediately indicated that there is interest in incorporating the technology into their disease management practices. Ten others have reached out for design parameters and two have visited to examine our research unit array.

1. Identify the UV-C radiation dose and timing required to inhibit the growth of Erysiphe necator (grape powdery mildew) and Botrytis cinerea (bunch rot).
2. Determine the suitability of UV-C radiation applications, under field conditions, for the management of powdery mildew and Botrytis bunch rot disease and its impact on fungicide-resistant pathogen populations.
3. Examine the suitability of an autonomous robotic platform to deliver UV-C applications at a commercial scale.
4. Determine the impact of UV-C application on fruit chemistry
5. Education and demonstration of the tractor-mounted and robotic UV-C arrays directly to producers