Illuminating Pest Management with the Help of the Washington State Wine Commission

Researchers and the Washington State Wine Commission Work to Address Threats to Wine Grapes

Nematodes, mealybugs, fungus and environmental hazards, like smoke, all threaten the production of Washington State wine grapes. A primary protector of the wine industry is the Washington State Wine Commission (WSWC), a wine-industry funded state agency designed to grow Washington’s wine industry through marketing, research, and education. WSWC works directly with researchers to fund cutting-edge research to address threats to the industry, including pheromone-based mating disruption for grape mealybug, irrigation management for grape variety, alternative nematode management, and mitigating smoke exposure effects on grape berry development. WSWC is my sponsor for the FFAR Fellows program and supports my research at Washington State University to address one of the most notorious threats to vineyards: grapevine powdery mildew.

Sampling for fungicide resistance in growers’ field. -Alexa McDaniel, Washington State University

Grapevine Powdery Mildew, a Fungus, Threatens Washington Wine Grapes

Grapevine powdery mildew is an obligate biotroph fungi that colonizes the surface of any green tissue. It appears as a white powdery growth on the surface of foliage, stems, and the most economically important part, the fruit. When vines are heavily infected it can lead to yield losses and negative effects in fruit quality, thus lowering the quality of wine. This disease is primarily managed with regular fungicide applications. With repeated applications of fungicide, however, comes an increased risk of resistance. Fungicide resistance to certain synthetic fungicides has been identified in some powdery mildew populations. Thus, there is a strong need to provide alternative pest management solutions, either through grower management or new technologies.

Ultraviolet-C (UV-C) light provides a new tool to manage grape powdery mildew. UV-C light is a short, highly energetic wavelength that is germicidal. UV-C has been used for nearly 80 years in hospitals and microbiology research to limit harmful microbes, but it’s effective use against plant pathogens, such as powdery mildew, is relatively recent. Nighttime application of UV-C is a key component in how UV-C can kill the fungus without harming the plant. Powdery mildews possess a robust photolyase repair mechanism that repairs UV-inflicted damage to a pathogen’s DNA. This repair mechanism is driven by the blue and UV-A light component of sunlight. In other words, blue and UV-A light, which is present in daylight, reverses any UV-inflicted damage incurred by UV-C light. Thus, applying at night bypasses this repair mechanism, allowing for a lower dose of UVC light that does not harm the plant but kills the mildew. We know this technology works against powdery mildew based on past research. My research focuses on how growers can effectively utilize this tool in their vineyards. We are answering questions on what application regimes are the most effective for Eastern, WA, so that growers can add this technological tool to help combat grapevine powdery mildew.

The WSWC’s direct involvement in this research means that I have the Washington wine industry’s support throughout my research program. I have been able to present this research at regional grower meetings and extension workshops to growers who are excited to learn how this research can benefit them. The growers have allowed me to visit their own vineyards to learn about their operations and to allow me to conduct research at their vineyard. This has led to fostering strong connections with local growers. This would not have been possible without funding from the WSWC.

The opportunity through the FFAR Fellowship to work more personally with the WSWC has allowed me to understand how the Commission functions and the uniqueness of the Washington wine industry. Mentorship from Melissa Hansen, WSWC Research Program Director, has been invaluable. She is a wealth of knowledge on communication, professionalism, and WA wine industry’s needs. Through her mentorship I have been able to observe WSWC board meetings and assist in WSWC sponsored events. Being a FFAR Fellow has taught me professional skills that I have utilized in my research and in my relationship with WSWC. I am excited to see where my future career will take me through the connections I have made with the help of the Commission and the FFAR Fellows Program.