2024 SOREC Smoke Trials
As summer nights turned into autumn mornings, smoke trials at Southern Oregon Research and Extension Center (SOREC) heated up. Part of Dr. Alec Levin and the Levin Lab’s research into the effects of wildfire smoke exposure on wine grapes, the dose-response smoke experiments used a custom-built vineyard smoking system to mimic conditions grapevines experience during wildfire season like those now common across the West Coast. These trials were designed to assess the impact of wildfire smoke on grapevine physiology and fruit quality by applying 6 levels of smoke to field-grown vines at two times of the year. Researchers simultaneously evaluated novel food-grade coatings that were specifically developed to protect grapes from smoke damage, and carefully monitored air quality throughout the experiments to link atmospheric smoke concentrations to resulting wine quality.
The work ultimately aims to provide updated best practices that winegrowers can use in real-world conditions to protect their crops. Executing these trials is no small feat, and was accomplished with support from collaborators across OSU’s College of Agricultural Sciences, UC-Davis, Washington State University, and Chateau Ste. Michelle Wine Estates, a key industry partner. These experiments are a small part of a larger project led by Dr. Elizabeth Tomasino, Professor of Enology in OSU’s Food Science & Technology Department, and supported by the Specialty Crop Research Initiative from the USDA’s National Institute of Food and Agriculture, as well as the USDA’s Agricultural Research Service, and the Oregon Agricultural Experiment Station.
With wildfires increasing in size and becoming more frequent in regions where wine grapes are produced, the negative impact from those fires on the resultant wines has become an unavoidable issue. Though wildfire smoke exposure in the vineyard generally reduces wine quality, its impacts greatly depend on numerous factors that researchers are actively investigating. For example, the proximity of the fire, fuel source, atmospheric conditions, freshness of the smoke, and number of smoke events all play a large role in determining the degree to which fruit will be impacted. The time of the year and developmental stage of the vines significantly changes the sensitivity of the grapes to smoke as well, with sensitivity increasing as harvest approaches. Additionally, growers lack the technology to protect their crop from smoke exposure in the vineyard. With these factors in mind, Dr. Levin and the larger team led by OSU are working to link air quality, plant physiology, and wine quality, all while developing new vineyard interventions aimed at protecting the fruit from smoke exposure.
To address the issues facing winegrowers, the Levin lab designed a special smoke application system to apply varying concentrations of smoke at different times of the growing season. The tight atmospheric control provided by the system allows the researchers to carry out a dose-response experiment – much like in pharmaceutical trials – in which multiple increasing smoke concentration levels are applied (dosed) to groups of grapevines and physiological responses are measured. In addition, the relative mobility of the system within the vineyard allowed the researchers to apply these treatments to vines at two different times of the year: just after the onset of ripening and one month later, just before harvest.
One of the interventions Dr. Levin and his lab are testing alongside their work focused on smoke impacts are sprayable coatings that might protect grapes from damage when applied before a smoke event. Using food-grade, cellulose nanofiber-based films developed by an OSU Food Science & Technology Department Professor Dr. Yanyun Zhao, Levin Lab smoke trials test the efficacy of using the spray coating to protect against volatile phenolic compounds such as guaicols, syringols, and cresols. These common smoke compounds are absorbed by the grape skins when wildfire smoke rolls in and can contribute to negative smoke impact and off-flavors in wine. As Dr. Levin notes, “If growers had an effective tool to protect their crop ahead of a smoke event, it would be a game-changer for the industry.”
After harvest, Dr. Tomasino and her lab take the reins. Fruit from all the various combinations of treatments – early vs. late smoke; low vs. high concentration; coating or no coating – will be analyzed for key smoke volatile phenols. Small-scale wines will also be made and analyzed for similar compounds and sensory characteristics to confirm that the treatment effects were carried through to the final product.
This is the first year of controlled smoke trials at SOREC, following two years of spray coating and smoking system development by Dr. Zhao’s team and Dr. Levin’s team, respectively. The Levin Lab team expects to complete data collection to share preliminary results with the rest of the team by early 2025.
While the spray coating is still in development, data garnered from the smoke trials is already being used to inform updated vineyard management practices for growers concerned about wildfire smoke impacts. Industry Partner, Clint Nelson of Chateau Ste. Michelle Wine Estates noted, “Wildfires are the biggest threat to wine quality that our industry faces, and the frequency of exposure seems to increase each year. Understanding the multifaceted relations of how smoke exposure can influence vine physiology and wine grape quality is critical to the sustainability of our business. It is reassuring to see Alec and his team collaborating with other OSU researchers and industry cohorts to devise solutions that will help protect growers, vineyards, and wineries. The work coming from these efforts will surely shape the future of the industry.”