Final Report – Funding Cycles 2020-2024, includes one year no cost extension
Principal Investigator: Michelle Moyer, Washington State University, Prosser
Telephone: 509-786-9234
Co-PIs: Walt Mahaffee, USDA-Agriculture Research Service, Corvallis; David Gadoury, Cornell University
Summary: This project funded for three years had two main objectives of evaluating the use of UV-C light as an alternative management strategy for grape powdery mildew and improving capacity for fungicide resistance testing/monitoring.
The effectiveness of UV-C light was evaluated under three distinct weather patterns from 2020-2022: slightly higher temperatures, a heat dome, and somewhat normal temperatures. Powdery mildew disease pressure was low the first two years, with little disease observed in the untreated controls, but the third year was average in terms of temperature and clear disease management differences were observed between UV-C, standard fungicide and untreated controls. Improved disease control was observed from UV-C with increased frequency of application. UV-C also worked well when used as part of a regime, rather than the sole management option. Advantages of UV-C were early season applications when sprays may not be feasible due to wind or rain and reduced pesticide inputs. Canopy management was found to have an influence and will be further studied. Though only minor impacts on grape mealybug crawlers were observed in lab assays, further study is warranted because these results occurred after only a single treatment, and UV-C light in the field would involve multiple treatments.
A fungicide resistance qPCR testing process was established at WSU Prosser IAREC. In 2021, the average sample turn-around time was four days. The research team also developed preliminary cost-sheets (price valid as of 2021), which allowed determination of actual cost per test reaction. This information can be used to assist both private and public laboratories in determining the feasibility of integrating this test into their offered services.
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