Bryan Berenguer | Brian Skahill | Manfred Stoll

Evaluation of Alternative Varieties in the Willamette Valley AVA using the Average Growing Season Temperature Index

Bryan Berenguer, Brian Skahill,* and Manfred Stoll
*Chemeketa Community College, Northwest Wine Studies Center, 215 Doaks Ferry Rd NW, Salem, OR, 97304 (bskahill@my.chemeketa.edu)

This analysis is a follow-up to a recent study that examined the ripening potential of Pinot noir in Oregon’s Willamette Valley (WV) American Viticultural Area (AVA). The study involved computations of the growing season average temperature (GST) viticulture climate classification index on a mean decadal basis from the 1950s to the 2090s using coupled model intercomparison project phase 5 (CMIP5) RCP4.5 and RCP8.5 projections of minimum and maximum daily surface air temperature. It considered the complete archive of the 32 CMIP5 daily localized constructed analogs downscaled historic data sets and their observational data that were used for downscaling and bias corrections to develop a weighted ensemble that optimized calculation of the GST index throughout the WV AVA. Using the GST index value range from 14.0 to 16.0°C for optimum suitability of Pinot noir (Vitis vinifera L.), the study results showed a progressive trend of decreasing area to support Pinot noir in the WV AVA for each RCP-emission scenario, which was more pronounced for the RCP8.5 scenario projections. This study applies the temperature-based GST bioclimatic index calculations that were developed for the WV AVA and the individual optimal GST index value ranges proposed by Greg Jones in 2006 for 20 other Vitis vinifera L. varieties, to evaluate alternative varieties that may be more suitable for ripening in the WV AVA due to climate change.

Funding Support: NA

Lauren Picone | Charlotte Decock | Cristina Lazcano

Assessing Long-Term Effects of Regenerative Management Practices on Vineyard Soil Health

Lauren Picone,* Charlotte Decock, and Cristina Lazcano
*Cal Poly, San Luis Obispo, 1802 14th St., Los Osos, CA, 93402
(laurenmpicone@gmail.com)

Vineyards are often developed on slopes or marginal lands, which results in soils that are particularly susceptible to erosion and degradation. To mitigate these impacts, regenerative management methods—including the use of cover crops, no-till, compost application, and livestock integration— can be used to improve soil health and increase soil organic matter. These practices can improve crop productivity and quality, water infiltration, nutrient availability, and carbon sequestration within soils. Because building soil health is a slow process, there is little knowledge regarding the effects of long-term use of regenerative management practices on vineyard soil health.
To improve soil health and create more resilient agricultural systems, this project aims to assess the effects of long-term management practices on vineyard soil health across an edaphoclimatic gradient in California. Soils were collected from 87 different vineyard blocks across CA, specifically targeting vineyard blocks where one or several regenerative practices have been adopted for five or more years. Following recommendations from the Soil Health Institute, all samples were analyzed for a minimum suite of soil health indicators, which included soil organic carbon concentration, carbon mineralization potential, and aggregate stability. For each vineyard block, growers completed a qualitative survey on the management history and the performance of the vineyard, including yield, crop quality, water, nutrient, and pest management. Our preliminary results show that finer-textured soils had more total soil carbon concentrations than coarse-textured soils in the vine and alley row. Total soil carbon concentrations in the vine and alley rows increased significantly with the number of years livestock integration had been adopted. Additionally, the years of livestock integration and adoption of no-till increased aggregate stability indices within the vine row. Texture class and location were more important in predicting total carbon and aggregate stability indices than the duration of practice adoption.

Funding Support: Foundation for Food and Agricultural Research, and CDFA

Influence of Vineyard Planting on Soil Physical and Hydraulic Properties

Devin Rippner,* Elizabeth Gillispie, Michelle Moyer, Markus Keller, Troy Peters, Collins Wakholi, Brandon Peterson, Amisha Poret-Peterson, Andrew McElrone, Gustavo Mendez-Soto, Anil Battu, and Tamas Varga
*USDA-ARS, 24106 N. Bunn Rd, Prosser, WA, 99350 (devin.rippner@usda.gov)

Vineyard soils are most disturbed during vineyard establishment, including pre-plant soil preparation, planting, and trellis installation. This process grossly alters soil physical and hydraulic properties in a repeating pattern across newly planted vineyard blocks. To study the influence of mechanical vineyard planting on soil hydraulic and physical properties, a suite of analyses was conducted on soils and soil cores taken from the vine (3) and tractor (3) rows of a newly mechanically-planted vineyard and an adjacent property of mixed uses, including as a vineyard, that has not been disturbed in at least five years. Soil bulk density was 30% greater in the tractor row and 20% greater in the no-till field compared to the vine row of the recently planted vineyard. Soil saturated hydraulic conductivity (Ksat) was significantly increased (100×) in the vine row compared to the tractor row. No-till soils had a Ksat ~10× greater than the tractor row and 10× less than the vine row, representing an almost optimal infiltration rate of ~20 cm/hr. Mean porosity measured by x-ray computed tomography was greatest in vine rows and least in the tractor rows. No-till soil showed not just extensive root colonization, but also extensive exploration by earthworms, contributing to the macroporosity and thus contributing significantly to the observed Ksat in the no-till soil. These results could guide vineyard planting practices to minimize soil disturbance and highlight the synergy between cover crops and soil fauna in improving important soil health properties like capturing water.

Funding Support: USDA Project # 2072-21000-057-000-D (A portion of) This research was performed on a project award (https://doi.org/10.46936/lser.proj.2021.51847/60000344) from the Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility sponsored by the Biological and Environmental Research program under Contract No. DE-AC05-76RL01830.

Using Passive Samplers to Measure Volatile Phenols in Smoke to Correlate to Concentrations in Grapes and Wines

Arran Rumbaugh,* Andrey Khlystov, Dave Campbell, Yeongkwon Son, Yan Wen, Chen Liang, Hao-Lin Fang, Christopher Wallis, and Anthony Wexler
*USDA-ARS, One Shields Avenue, Davis, CA, 95616 (arran.rumbaugh@usda.gov)

Smoke generated from wildfires can detrimentally affect grape and wine composition through increased concentrations of volatile phenols (VPs) and their glycoconjugates (bound), a phenomenon termed “smoke taint”. This study evaluated passive samplers as a method for monitoring the levels of VPs in ambient wildfire smoke that are known to contribute to smoke taint in wines. Cabernet Sauvignon grapes and passive samplers were exposed to smoke under controlled conditions to evaluate the efficacy of passive samplers across various smoke intensities. Smoke was generated from oak chips using a custom-built smoking chamber that consisted of: an infrared heating burner system, a polycarbonate chamber internally lined with Teflon sheets, and a ventilation system to operate the system under negative pressure and eliminate emissions. Grapes and samplers were exposed to four different smoke levels: control exposure (CE, no smoke), low exposure (LE, 0.5 hrs, ~20 g oak wood), medium exposure (ME, two hrs, ~60 g oak wood), and high exposure (HE, four hrs, ~180 g oak wood). Afterward, triplicate microfermentations (0.5 L) were performed per treatment. Passive samplers were analyzed using thermal desorption (TD) coupled to gas chromatography-mass spectrometry (GC-MS). Grapes and wines were analyzed for free and bound VPs using GC-MS/MS (free) and LC-MS/MS (bound). Free and bound VPs in grapes and wines correlated positively with VP levels in passive samplers. Linear regression analysis of free VPs indicated a good linear fit between passive samplers and grape samples for all compounds, with R2 values between 0.9999 and 0.9985 for guaiacol, methyl guaiacol, 4-ethyl guaiacol, and o-, p– and m-cresol. This study was the first step to determine the efficacy of using passive samplers as an early warning system in vineyards. Future experiments will correlate passive sampler VP levels to grape and wine composition across several smoke intensities, exposure durations, and repeat exposures to build a predictive model.

Funding Support: USDA-ARS funded research

Jessica Williamson | Richard Petrone | Riccardo Valentini | Andrew Reynolds

Heard it Through the Grapevine: Assessing the Spatial Variability of Hydrometeorological Controls in Canadian Vineyards

Jessica Williamson,* Richard Petrone, Riccardo Valentini, and Andrew Reynolds
*University of Waterloo, 200 University Ave., Waterloo, ON, N2L 3G1, Canada (ja5willi@uwaterloo.ca)

Canada’s wine industry contributes over $11 billion toward the national economy, of which $5.5 billion is generated by Ontario wineries. The cultivation of high-quality grapes to produce economically valuable wines does not come without challenges to growers and winemakers alike. Spatial variability in microclimate and soil conditions have been a long-standing challenge to growers since the start of grapevine cultivation. With the added pressures of adapting to climate change, vineyards will require special management adaptations to achieve high-quality berry yields and wines. The role of spatial variability on grape quality is especially important within the three principal growing regions of Ontario, Canada. Here, climate is shifting toward longer and warmer growing seasons, with variable precipitation patterns that present additional threats to growers, in addition to those that already exist due to vineyard spatial variability. This research used a combination of methods aimed at assessing hydrometeorological components, site-wide and between different blocks and rows and among individual grapevines, to best understand spatial differences across two vineyards in the Niagara growing region. VineTalkers, an innovative new tool for collecting biophysical data across large heterogeneous landscapes from individual plants, collected data on water transport, leaf spectrometry, below-canopy radiation, and various microclimatic measurements. Preliminary results showed homogeneity across blocks for subcanopy air and soil temperatures, while variability was present for soil moisture and sap flow (transpiration) conditions. This data, paired with meteorological and eddy covariance tower findings, presents an opportunity for growers to understand the current state of their vineyards and the spatial variability across their crop, allowing them to make specific, non-uniform management decisions to enhance grape yield and quality each growing season.

Funding Support: Global Water Futures, Ontario Grape and Wine Research Inc.

Cody Copp | Aidan Wiggins | Melinda Cramp

Sunscreen for Grapevines: Kaolin Clay Use in Pacific Northwest Vineyards

Cody Copp,* Aidan Wiggins, and Melinda Cramp
*Oregon State University, 418 N Main Street, Milton-Freewater, OR, 97862 (cody.copp@oregonstate.edu)

Short-term climate change effects like extreme heat threaten grape production in the Pacific Northwest. Extreme temperatures inhibit photosynthesis, reduce yield, delay ripening, and promote fruit sunburn. Kaolin clay is used in other crops to reduce heat stress and sunburn. Additionally, other labeled (insect suppression) and experimental (wildfire smoke exposure) uses distinguish kaolin as a viticultural tool to mitigate climate change-related risks.

Multiple field experiments were established in 2022 and 2023 in commercial vineyards near Milton-Freewater, Oregon to optimize kaolin application (i.e., rate, timing, adjuvant use), observe fruit sunburn effects, and measure effects on leafhopper populations. In one block of Vitis vinifera L. cv. Syrah, kaolin was applied between fruit set and harvest at varying rates (0, 11, 22, or 45 kg/ha), at different times (pre- and postveraison), and with commercial adjuvants. The effect on sunburn was tested with fruit zone leafing on the afternoon side of Syrah and Tempranillo vines with label rate kaolin application to half of clusters prior to a postveraison heat event (three days above 41°C). At a second site, kaolin was applied to organic Cabernet Sauvignon and populations of Erythroneura elegantula adults and nymphs were monitored from bloom until harvest.

In 2022, kaolin at 45 kg/ha improved stomatal conductance above Ψ_leaf of -1.4 mPa, increased fruit yield by 5%, and slightly improved anthocyanin concentration. In 2023, tannin and anthocyanin concentrations increased with application rate and were greater with preveraison application. Visual assessment indicated that all adjuvants dramatically improved dispersion and deposition of kaolin on berries. Application prior to a heat event reduced the impact of sunburn on marketable yield and quality; treated clusters had 52 to 85% fewer shriveled berries and up to 25% higher anthocyanin concentration. Kaolin application reduced the peak population of second generation E. elegantula nymphs by 54%.

Funding Support: Agricultural Research Foundation, Oregon Wine Research Institute

Nataliya Shcherbatyuk | Patricia Skinkis | Terry Bates | Manoj Karkee | Markus Keller

HiRes Vineyard Nutrition Project Seeks to Develop New Tools and Refine Nutrient Thresholds

Nataliya Shcherbatyuk, Patricia Skinkis, Terry Bates, Manoj Karkee, and Markus Keller*
*WSU, Prosser IAREC, 24106 N. Bunn Rd., Prosser, WA, 99350 (mkeller@wsu.edu)

Vineyard nutrient management is essential to maintain vine health, productivity, and fruit quality targets. However, conventional vine tissue methods are labor intensive, costly, lack standardization, and lack the ability to describe nutrient status spatially across vineyards. Our interdisciplinary team is refining tissue sampling techniques and creating decision-support remote-sensing tools for real-time assessment of vineyard nutrient status. The project has four objectives: 1) develop non-destructive tools to measure grapevine nutrient status, 2) determine the efficiency and suitability of precision vineyard nutrient management, 3) define grapevine nutrient thresholds based on environment and production market, and 4) estimate the economic impact and feasibility of nutrient management decisions and extend knowledge. The project is generating vineyard nutrient prediction maps by employing hyperspectral sensors calibrated against vine tissue nutrient data. Field trials involving nitrogen, potassium, and magnesium supplementation in wine, table, raisin, and juice grape varieties were conducted according to local nutrient-limitation conditions in WA, OR, CA, NY, and VA. To address improved season-long sampling, tissues were collected and analyzed at growth stages spanning from dormancy to leaf fall. To share project updates with industry and peers, the team provided field events, podcasts, and train-the-trainer programs. By integrating new technologies with vineyard nutrient management practices, this project aims to provide stakeholders with new options for vineyard nutrient monitoring that will improve decision-making within the grape production sector.

Funding Support: USDA National Institute of Food and Agriculture-Specialty Crop Research Initiative Coordinated Agricultural Projects (CAP) grant project award number: 2020-51181-32159.

Nataliya Shcherbatyuk | Patricia Skinkis | Terry Bates | Manoj Karkee | Markus Keller

HiRes Vineyard Nutrition Project Seeks to Develop New Tools and Refine Nutrient Thresholds

Nataliya Shcherbatyuk, Patricia Skinkis, Terry Bates, Manoj Karkee, and Markus Keller*
*WSU, Prosser IAREC, 24106 N. Bunn Rd., Prosser, WA, 99350 (mkeller@wsu.edu)

Vineyard nutrient management is essential to maintain vine health, productivity, and fruit quality targets. However, conventional vine tissue methods are labor intensive, costly, lack standardization, and lack the ability to describe nutrient status spatially across vineyards. Our interdisciplinary team is refining tissue sampling techniques and creating decision-support remote-sensing tools for real-time assessment of vineyard nutrient status. The project has four objectives: 1) develop non-destructive tools to measure grapevine nutrient status, 2) determine the efficiency and suitability of precision vineyard nutrient management, 3) define grapevine nutrient thresholds based on environment and production market, and 4) estimate the economic impact and feasibility of nutrient management decisions and extend knowledge. The project is generating vineyard nutrient prediction maps by employing hyperspectral sensors calibrated against vine tissue nutrient data. Field trials involving nitrogen, potassium, and magnesium supplementation in wine, table, raisin, and juice grape varieties were conducted according to local nutrient-limitation conditions in WA, OR, CA, NY, and VA. To address improved season-long sampling, tissues were collected and analyzed at growth stages spanning from dormancy to leaf fall. To share project updates with industry and peers, the team provided field events, podcasts, and train-the-trainer programs. By integrating new technologies with vineyard nutrient management practices, this project aims to provide stakeholders with new options for vineyard nutrient monitoring that will improve decision-making within the grape production sector.

Funding Support: USDA National Institute of Food and Agriculture-Specialty Crop Research Initiative Coordinated Agricultural Projects (CAP) grant project award number: 2020-51181-32159.

Arpa Boghozian | Cristina Medina-Plaza | Reddy Kishorekumar | Mysore Sudarshana | Anita Oberholster

Impact of Grapevine Red Blotch Virus Infection on Grape Skin Cell Wall Composition over Two Growing Seasons

Arpa Boghozian, Cristina Medina-Plaza, Reddy Kishorekumar, Mysore Sudarshana, and Anita Oberholster*
*University of California, Davis, 595 Hilgard Lane, Davis, CA, 95616 (aoberholster@ucdavis.edu)

Grapevine red blotch virus (GRBV), a member of the Geminiviridae family and vectored by the three-corned alfalfa treehopper Spissistilus festinus, causes delayed grape ripening and decreased wine phenolic content. However, wine phenolic content does not correlate linearly with concentrations in grape skin cell walls (GSCW). Phenolics are stored in GSCW vacuoles with extraction into macerating juice affected by the hemicellulose, pectin, and structural protein content of cell walls. GRBV’s effect on GSCW was studied using virus-infected, GRBV(+), and noninfected, GRBV(-) vines from a commercial vineyard in Paso Robles, CA in 2021 and 2022. Biochemical analysis involved GSCW isolations as alcohol-insoluble residue, total protein content (TPC) using the Coomassie blue protein assay, and pectin concentration measured as uronic acid. TPC was lower in GRBV(+) than in GRBV(-) in 2021 and 2022 grapes at harvest and in postveraison GRBV(+) grapes in 2021. In 2022, there was less TPC in GRBV(+) and GRBV(-) grapes than in 2021. TPC decline in 2022 can be attributed to increased heat degradation or suspension of total protein production due to environmental factors such as more growing degree days and lower annual precipitation. Further investigation will uncover the relationship of TPC with pathogenesis-related protein production during infection. GRBV(+) GSCW exhibited greater pectin in both seasons, possibly due to a ripening delay with downregulated pectin enzyme activity or upregulated pectin synthesis, since concentrations in GRBV(+) grapes at preveraison, postveraison, and harvest in both vintages were greater. Pectin concentration has been previously proven to be inversely correlated with phenolic extractability due to firmness of the GSCW. Future steps involve using gas chromatography coupled with mass spectrometry to assess the effect of GRBV on GSCW monosaccharide linkages.

Understanding the viral effect on GSCW and its correlation with phenolic extractability will help determine mitigation strategies for the winemaking industry.

Funding Support: CDFA-PD/GWSS Board, Jastro-Shields Research Award, American Society of Enology and Viticulture Traditional Scholarship, NIFA Specialty Crops Research Initiative

Ashraf El-kereamy | Ahmed Ismail | Tariq Tariq | Alaaeldin Rezk | David Obenland

Exploring Berry Astringency in Table Grapes

Ashraf El-kereamy,* Ahmed Ismail, Tariq Tariq, Alaaeldin Rezk, and David Obenland
*University of California Riverside, 900 University Ave, Riverside, CA, 92521 (ashrafe@ucr.edu)

Scarlet Royal, a mid-season ripening table grape, is a popular red grape variety in California. However, its berries develop an undesirable astringent taste under certain conditions. A series of trials have been conducted to comprehend the underlying mechanism and control of astringency development. First, we used total phenolic analysis to determine the components responsible for the astringent taste. Second, we identified the pathway involved in this process. By comparing Scarlet Royal berries with non-astringent varieties, we determined the threshold of tannin levels that cause the berry’s astringent taste. Our data showed that berry astringency is correlated with high petiole nitrogen levels and can be managed through N fertilization. Additionally, our data showed that a lower cluster number per vine could contribute to the induction of berry astringency. Further, berry astringency is associated with late harvest dates after the middle of September; however, it is not associated with high sugar content, as some people believe. It was associated with a lower level of anthocyanin in the berries at harvest. Table grapegrowers could control the induction of berry astringency in Scarlet Royal table grape by monitoring and maintaining a reasonable N level during flowering and berry development, and by not reducing the cluster number to 20 clusters per vine.

Funding Support: California Table Grape Commission

Alexander Gapinski | Suzanne Slack | Aude Watrelot

Could Foliar-Applied Prohexadione Calcium and Phenylalanine Affect the Phenolic Content of Marquette?

Alexander Gapinski, Suzanne Slack, and Aude Watrelot*
*Iowa State University, 536 Farm House Ln, Ames, IA, 50011 (watrelot@iastate.edu)

Cold-hardy hybrid grape cultivars have less tannin than Vitis vinifera cultivars, which leads to low-quality, unbalanced red wines. Foliar sprays of phenylalanine (Phe; 100 mg/L) and prohexadione calcium (ProCa; 50 mg/L) were applied separately and in combination (ProCa + Phe) to Marquette grown in Iowa throughout the 2022 and 2023 growing seasons. ProCa was applied to change the plant cell wall structure and modify tannin extractability. Phe is a precursor of flavanoid biosynthesis. Treatments were assigned following a split-plot design to three-vine panels with six replicates. Samples from treated vines were compared to untreated control samples using an additive effects linear regression model with random intercepts. Basic chemical properties, tannin content (high-performance liquid chromatography-diode array detection), and iron-reactive phenolic (UV-vis spectrophotometry) content of juice, wine, and skin and seed extracts were analyzed at five phenological time points. In 2022, the ProCa treatment had lower titratable acidity at three weeks post-fruit set, but Brix, pH, hue, and color intensity were unaffected at any time point. At the mid-ripening time point, Phe showed a positive effect on juice tannin concentration. However, the model showed that when Phe and ProCa + Phe treatments were applied, skin tannin and iron-reactive phenolic contents were negatively affected. Seed phenolic content was not affected by foliar-applied Phe or ProCa. Overall, limited effects on tannin and IRP contents were observed in different grape tissues, which may be explained by the low doses of Phe and ProCa used in this study. However, analysis of 2023 data is ongoing to investigate the effectiveness of Phe and ProCa foliar sprays at managing phenolic content in Marquette grapes over two growing seasons.

Funding Support: No external funding.

Rushil Patel | Satyanarayana Gouthu | Laurent Deluc

Exploring Auxin Responsive Factor 4’s Influence on Timing of Ripening Initiation Using Molecular Breeding

Rushil Patel, Satyanarayana Gouthu, and Laurent Deluc*
*Oregon State University, 2750 SW Campus Way, Room 4121, Corvallis, OR, 97331 (delucl@oregonstate.edu)

Genetic manipulation is a major tool in determining gene function and its relationship with traits of interest in plants. For any crop, it requires a tractable genetic transformation system and a reliable expression system to turn on or switch off expression of targeted genes. We implemented the microvine system for Agrobacterium tumefaciens-mediated transformation and a plant gene switch system to control the transgene expression by supplying transgenic greenhouse plants (through root-drenching) a chemical inducer, methoxyfenozide. As proof of principle, we conducted gain and loss of function studies on Auxin Responsive Factor 4, a transcription factor that may contribute to the timing of ripening initiation in grape berries. We developed three types of constructs. In construct 1, we aimed to induce over-expression of the native endogenous ARF4. In construct 2, we generated transgenic lines containing a synthetic ARF4 resistant to miRNA-mediated gene silencing (miRARF4). In construct 3, we created ARF4-silencing lines using artificial miRNA technology. To pinpoint plants with the most response to the chemical inducer, eight plants from each construct were grown to maturity and induced over a month with leaf collections at select points. Six collection times were chosen to comprehend both the short-term responses (days 0, 3, 7, and 10) and the reversibility of the system (days 14 and 31). The data extracted using qPCR allowed us to characterize the time period of greatest induced transgene expression. Expression levels of the most responsive plants were eight-fold in the native construct, 100-fold in miRARF4, and 1000-fold increase in the ARF4 silencing line. Ongoing experiments quantitatively compare expression levels in berry samples to verify the inducibility dynamics in the fruit. Once confirmed, the study intends to focus on comparing ARF4’s targetome among the three constructs by using genome-wide transcriptomic analyses.

Funding Support: Oregon Wine Board, Erath/Family Foundation, Oregon Wine Research Institute

Abram Smith | Satyanarayana Gouthu | Charles Dearing | Laurent Deluc

Identifying Protein-Protein Interactions in Red Blotch Infected Vines

Abram Smith, Satyanarayana Gouthu, Charles Dearing, and Laurent Deluc*
*Oregon State University, 2750 SW Campus Way , Corvallis, OR, 97331 (laurent.deluc@oregonstate.edu)

Grapevine red blotch virus (GRBV) poses a significant threat to winegrape production. Host factors critical for red blotch infection remain largely unknown in grapevines, impeding attempts to use CRISPR technology to generate red blotch-resistant grapevines. Our project seeks to identify these host factors. Our two main objectives are to identify the host factors using the yeast two-hybrid (Y2H) system and to validate their interaction with viral proteins in planta. For the Y2H experiment, we will conduct a comprehensive genome-wide screen using GRBV replication-associated proteins (C1, C2, C3, and C1-2) as baits against a comprehensive grapevine cDNA library from GRBV-infected plants as preys. Based on the strength of the interactions and their biological relevance from previous studies, we will select the top two most promising interactors for each bait (C1, C2, C3, C1+2) to conduct bimolecular fluorescence complementary assays from isolated grapevine protoplasts. All four baits have been successfully cloned into yeast, initiating the screening process. A prey library using coding-gene related RNA is currently being constructed. The next step will be to carry out mating of the bait and prey, as well as isolation of mated yeast. Further screenings on a series of selective media will identify high-confidence interactors, followed by Sanger sequencing to identify their biological function. To get ahead of the work on objective 2, we have optimized a protocol to isolate protoplasts from tissue cultured cells of microvines. If we reach our goals, we will lay the groundwork for further studies to produce CRISPR-engineered, GRBV-resistant grapevines.

Funding Support: California Department of Food and Agriculture

A Two-Year study of 12 Sustained and Regulated Deficit Irrigation Schedules for Cabernet Sauvignon in Central California

Vincenzo Cianciola, Luca Pallotti, Alessandro De Rosa, Peyton Peralez, Desiree Hernandez, Luis Ortiz, William Whalen, Eve Laroche-Pinel, and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)

Amidst escalating drought conditions in the San Joaquin Valley, where grapegrowers face an urgent need for effective water management strategies, this study contributes valuable insights for sustainable viticulture practices. Recognizing the pressing importance of optimizing water use in vineyards, particularly in the context of the West San Joaquin Valley, this research aims to unravel the physiological responses of grapevines under varying intensities and timings of sustained and regulated deficit irrigation.

Focused on a singular commercial Cabernet-Sauvignon × 1103 Paulsen vineyard, this study explored the impact of irrigation treatments administered during 2022 and 2023 seasons. Employing a semi-autonomous irrigation approach, actual water quantities were recorded using flow meters. The study incorporates sustained deficit irrigation (SDI) schedules with varying percentages (40, 60, 80 and 100% of ET_c) and regulated deficit irrigation (RDI) strategies in both preveraison and postveraison periods (e.g., 100/40, 80/60, 60/100).

Stem water potential and gas exchange were measured from June to harvest, grape composition from veraison to harvest and yield components were also assessed at harvest time. Results show that while the 40% SDI significantly underperformed 100% ET_c, it is possible to obtain similar or better results while saving water with RDI and SDI treatments with lower ET_c reductions.

This research determined the primary effects of these irrigation regimes on plant water status, gas exchange, berry composition, and yield components. The findings aim to provide a nuanced understanding that can inform advanced developments in water management strategies, offering practical insights for grapegrowers navigating the challenges of water scarcity in the San Joaquin Valley.

Funding Support: American Vineyard Foundation, California State University – Agriculture Research Institute

Alessandro De Rosa | Luca Pallotti | Eve Laroche-Pinel | William Whalen | Luca Brillante

Enhancing Water Use Efficiency and Berry Ripening in Cabernet Sauvignon: Effects of Irrigation Regimes and Biostimulants

Alessandro De Rosa, Luca Pallotti, Eve Laroche-Pinel, William Whalen, and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)

Water availability is a key factor for agriculture, as rising temperatures increase plants’ water demand, while water resources become increasingly limited.

Optimizing water use efficiency is essential to enhance vine tolerance to heat stress and ensure high productivity. This study examines the effects of four distinct irrigation regimes: vines irrigated at 50, 75, and 100% of estimated crop evapotranspiration (ET_c), alongside regulated deficit irrigation (RDI), employing 50% of vine ET_c from fruit set to veraison and 100% from veraison to harvest, both independently and in combination with a biostimulant during the 2023 growing season. Measurements were taken for stem water potential, gas exchange, berry ripening, and yield at harvest of Cabernet Sauvignon vines. The biostimulant did not affect vine physiology, as stem water potential, gas exchange, and water use efficiency remained unchanged between treated and untreated vines. There were differences related to irrigation amount, with greater water supply leading to lower stress conditions and increased photosynthetic activity. However, this improvement came at the cost of reduced water use efficiency when compared with the 50% irrigation and RDI treatments, which had the greatest efficiency. The biostimulant increased berry and cluster weight without affecting berry ripening in combination with 50, 75, and 100% irrigation, but not with RDI. The water regime had a significant effect on juice composition, with the 50% treatment hastening berry ripening and the 100% treatment delaying it. Interestingly, RDI had the most pronounced effect on ripening, slowing down sugar accumulation and preserving organic acids.

Even though the effects of the biostimulant were limited, this study underscores that restricting water during periods when vine demand is limited represents a sustainable approach to enhance water use efficiency and delay berry ripening.

Funding Support: N/A

Desiree Hernandez | Alessandro De Rosa | Eve Laroche-Pinel | Luca Brillante

A Comparative Study of Traditional Drip Irrigation and Deep Underground Irrigation to Improve Water Use Efficiency

Desiree Hernandez, Alessandro De Rosa, Eve Laroche-Pinel, and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)

Water efficiency is crucial for grapevine cultivation, especially in regions like California where water scarcity poses significant challenges. In 2023, a comprehensive project was initiated in Madera, CA, aimed at comparing the efficacy of traditional drip irrigation with a novel, deep-underground irrigation system in sustaining grapevine water status. The experiment comprised eight blocks, each with four vines, with four blocks irrigated conventionally using drip irrigation and the remaining four with a deep underground irrigation setup.

From June to August 2023, three water-related metrics were measured five times: stem water potential (Ψ_stem), stomatal conductance (g_s), and net assimilation rate (AN). Ψ_stem measurements showed a discernible disparity in mid-July, coinciding with peak water stress conditions. During this critical period, vines under traditional drip irrigation exhibited lower average Ψ_stem (-1.24 MPa) than those under deep irrigation (-1.13 MPa). Throughout the observational period, vines subjected to deep irrigation consistently demonstrated superior physiological performance. Specifically, AN remained consistently higher under deep irrigation, with an average difference of 2.6 µmol CO²/m²sec compared to drip irrigation. Similarly, g_s values were consistently elevated under deep irrigation, with an average difference of 65.9 mmol H₂O/m²sec except during the initial stages of the trial.

These findings underscore the efficacy of deep irrigation in mitigating water stress and enhancing grapevine physiological functions compared to traditional drip irrigation methods. The study provides valuable insights into the potential of deep underground irrigation systems to optimize water usage and sustain grapevine health and productivity in water-scarce environments. Ultimately, such innovative irrigation approaches hold promise for improving water efficiency and promoting sustainable viticulture practices in CA and beyond.

Funding Support: N/A

Tingting Ye | Michael Qian | Alexander Levin | Yanping Qian

Effect of Irrigation Initiation Time on Methoxypyrazine and C13-norisoprenoid Composition in Pinot noir Wine

Tingting Ye, Michael Qian,* Alexander Levin, and Yanping Qian
*Department of Food Science and Technology, Oregon State University, 100 Wiegand Hall, Corvallis, OR, 97331 (michael.qian@oregonstate.edu)

This study investigated the influence of initiated irrigation time on the methoxypyrazine and C13-norisoprenoid compositions of Pinot noir wine. The experiment was conducted in three subregions of the Rogue Valley in southern Oregon for two years, and the Pinot noir vines were irrigated at different irrigation initiation times based on normalized vine water status thresholds (ΔSWP). The ΔSWP was defined as the departure of measured midday stem water potential from the calculated non-water-stressed baseline, varied from 0.2 MPa (control) to the most delayed irrigation (1.0 MPa) in five irrigation initiation times, while the irrigation amount was set at 70% ET_c, based on industry standard. Wines produced in each of the two vintages were analyzed. Methoxypyrazines and C13-norisoprenoids in the wine were analyzed by headspace solid-phase microextraction gas chromatography-mass spectrometry and stable-isotope labeled compounds were used as internal standards for quantification. The results showed that the delayed irrigation initiation time decreased the methoxypyrazine levels and increased C13-norisoprenoid levels in the wines, although the trends depended on vintage and subregion. These changes in volatile composition in response to irrigation initiation timing could affect aroma perception and overall wine quality. Determination of the optimal irrigation initiation timing can provide a guideline for grapegrowers to produce high-quality winegrapes and reserve water resources.

Funding Support: Northwest Center for Small Fruits Research Commission, USDA

Luca Brillante | Abiodun Abioye | Eve Laroche-Pinel | Brent Sams

Toward Real-Time Selective Harvesting and Grape Composition Mapping by Integrating Hyperspectral Sensing into Harvesters

Luca Brillante,* Abiodun Abioye, Eve Laroche-Pinel, and Brent Sams
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)

Understanding grape composition at harvest is vital for winemakers and growers to make informed decisions regarding grape processing and wine quality. The composition of grapes, including sugars (total soluble solids), pH, total acidity (titratable acidity), and anthocyanins, directly influences the flavor, aroma, and quality of the resulting wine. Unfortunately, grape composition varies in space because of environmental and managment factors. Implementing variable rate management can help underperforming areas recover or can help separate areas for selective production of different wines. Unfortunately, current sensing methods map grape composition indirectly. Selective harvesting cannot be implemented in real-time, requiring two separate passes to harvest the same vineyard block, increasing the time and logistic complexity of the harvest.

In this project, a novel approach using hyperspectral imaging technology mounted on the conveyor belt of a mechanical harvester was employed to assess grape composition on the go. The hyperspectral camera captured images within the shortwave infrared (SWIR) domain, ranging from 900 to 1700 nm. This spectral range allows for detecting specific molecular vibrations associated with various chemical compounds present in grapes, such as sugars, acids, and water content.

The images obtained from the hyperspectral camera were processed using advanced segmentation techniques to extract only the grape signal, effectively isolating the relevant spectral information for analysis. By focusing solely on the grape signal, the project aimed to minimize interference from background noise and non-grape elements, ensuring the accuracy of the composition assessment. The extracted grape signal was used to predict grape composition through previously trained machine-learning algorithms and predictions were compared to ground data collected on grape samples from 100 vines. Through this predictive modeling approach, the project seeks to develop a reliable and non-destructive method to assess grape composition in real-time during harvest. This could empower mapping and separate grape composition for on-the-fly, one-pass selective harvesting.

Funding Support: American Vineyard Foundation; California State University – Agriculture Research Institute

Hava Delavar | Harlene Hatterman-Valenti | Ozkan Kaya | Summaira Riaz

Advancing Cold Hardiness Evaluation in Grapevine Mapping Populations

Hava Delavar, Harlene Hatterman-Valenti,* Ozkan Kaya, and Summaira Riaz
*North Dakota State University, 1360 Albrecht BLVD. Loftsgard, Fargo, ND, 58105 (h.hatterman.valenti@ndsu.edu)

Cold hardiness is an economically important trait that can significantly affect grape production and quality. Until now, there have been no reports identifying effective quantitative trait loci (QTL) for cold hardiness in grapevines. The bottleneck for QTL mapping of cold hardiness in grapes and other fruit trees is field evaluation, because plants vulnerable to cold often die in their first year of planting. To address this, our study focuses on developing a method that involves acclimating the entire mapping population in the greenhouse with controlled photoperiod and temperature, allowing comprehensive assessment of both cold-susceptible and cold-hardy genotypes using differential thermal analysis. Our primary objective is to establish a method that ensures results obtained from cold evaluation of accessions acclimated in the greenhouse have the same ranking as cold evaluation results from the same accessions under field conditions. For this purpose, a mapping population resulting from a cross between Vitis riparia and Vitis vinifera underwent cold hardiness evaluations under three distinct environments: 1) acclimated in a cold region of North Dakota that experiences temperatures as low as -35°C during winter; 2) acclimated in a greenhouse, where photoperiod and temperature were controlled; and 3) acclimated in the temperate climate of California, devoid of any cold stress. Hardiness monitoring was conducted using the widely accepted analysis method of differential thermal analysis. This research can speed up the breeding processes, as evaluation in the greenhouse can be done at any time of year and is not limited to winter. Data analysis for the study is ongoing, so the findings have not been disclosed at this stage. We anticipate completing the requisite analyses and presenting the results by the time of the Conference.

Funding Support: North Dakota Department of Agriculture Specialty Crop Block Grant

Kenneth Donsky, | Benjamin Ramsell | Britt Eubanks | Laurent Deluc

Accelerating Molecular Breeding via Development of a Novel Multiplexed Gene-Editing Method for Vitis vinifera

Kenneth Donsky,* Benjamin Ramsell, Britt Eubanks, and Laurent Deluc
*Oregon State University, 1450 NW Division Street, Apartment 32, Corvallis, OR, 97330 (donskyk@oregonstate.edu)

Genome editing can aid breeding programs dedicated to delivering genetically improved material from crops that will not be able to adapt to rapidly evolving climate change. Using the microvine system, we developed a research program to produce high-throughput gene-edited collections of grapevine mutants for easy gene-to-trait interrogations. To achieve this goal, we pursued the following three primary objectives: i) improve plant regeneration from Agrobacterium tumefaciens-mediated transformation events in somatic embryogenic grapevine cells, ii) increase the editing rate using a specific variant of the CRISPR/Cas9 protein, and iii) evaluate the potential of a new nanomaterial, carbon nanodots (CDs), to deliver multiple single guide RNAs for multiplexed editing. The approach to achieve objective 1 involves using the conditional expression of the morphogenic and synthetic gene, miRGRF_GIF4, from Vitis vinifera. For objective 2, we will compare the editing rate of different versions of the CRISPR/Cas9 editing system. In objective 3, we propose to identify the ratio of CD:sgRNA for optimized delivery to embryogenic grapevine cells. Zinc-functionalized CDs have been selected for their ease of synthesis and zinc’s affinity for nucleic acids. If we achieve our goals, we will give the scientific community a new tool for generating KO mutant collections that could expand beyond the grapevine model.

Funding Support: USDA NIFA

Christian Mandelli | Laurent Deluc

Spray-Induced Gene Silencing (SIGS) with Carbon Dots for Enhanced RNA Delivery in Grapevine

Christian Mandelli* and Laurent Deluc
*Oregon State University, 2750 SW Campus Way, Corvallis, OR, 97331 (mandellc@oregonstate.edu)

Spray-induced gene silencing (SIGS) is a recent technology that enhances a plant’s immune system. It involves the ectopic application of double-stranded RNAs (dsRNAs) to trigger a plant’s defense mechanism, known as RNA-interference (RNAi). Unlike traditional methods relying on the generation of transgenic plants, SIGS offers a rapid and targeted disease management solution. By transiently enhancing RNAi, it eliminates the need for resources and time-consuming development of resistant plants. However, SIGS application in tree crops encounters significant challenges, including limited cellular uptake and environmental stability of dsRNAs. To address these limitations, we explored an innovative approach that combines SIGS with branched polyethyleneimine-functionalized carbon dots (CDs) as nanocarriers, which enhanced dsRNA stability and cellular uptake. We developed a cost-effective, microwave-assisted protocol to synthesize 10 nm monodispersed CDs, that achieved >50% protection of dsRNA against RNase III degradation at a 200:1 (w/w) ratio. These CDs effectively improved cellular uptake, demonstrated by the successful delivery of CD-complexed fluorolabeled-dsRNAs (Cy3-RNA) into intact plant tissue-cultured cells. To prove the applicability of this formulation in planta, we sprayed Cy3-RNA with CDs on the abaxial surface of greenhouse grapevine leaves via low-pressure spray. Fluorescence microscopy revealed penetration of Cy3-RNA into stomata and neighboring cells. Additionally, the efficacy of CD-complexed dsRNA in triggering RNAi was validated using a 21-mer dsRNA targeting eGFP in eGFP-expressing microvines. Notably, no cytotoxic effects were observed following CD application. Ongoing research quantitatively compares eGFP expression of microvine leaves sprayed with CD-complexed and naked dsRNA through qPCR, to demonstrate the improvement in nucleic acid delivery associated with CDs. This innovative approach aims to overcome critical barriers for dsRNA delivery, particularly those associated with cell wall-related constraints in plants. Through optimization of RNAi-based defense strategies in grapevine, this research contributes to advancement of sustainable viticulture practices.

Funding Support: Erath Family Foundation, Oregon Wine Board

Simulating Natural Wildfire Smoke Events in a Vineyard: Challenges and Solutions

Suraj Kar, Ricky W. Clark, Joseph B. DeShields, Ian Ivey, Cole Cerrato, Elizabeth Tomasino, and Alexander D. Levin*
*Oregon State University, Southern Oregon Research & Extension Center, 569 Hanley Road, Central Point, OR, 97502 (alexander.levin@oregonstate.edu)

Changing climate is increasing wildfire events across the United States, exposing some of the most productive vineyard regions of the world to wildfire smoke. Wildfire smoke contains thousands of chemical compounds that can diminish growth and productivity of grapevines, delay ripening, and impart an offensive flavor in wine referred to as “smoke taint.” However, these effects are contingent upon numerous factors, including time and distance of the smoke event, smoke concentration, fuel type, and growth stage of the vine. Field experiments involving custom-built smoking chambers, described in previous research, have provided inadequate information on how to simulate a natural wildfire event and achieve a predetermined smoke concentration within these chambers. Therefore, a field trial was conducted at the Southern Oregon Research and Extension Center in the Rogue Valley AVA, where chambers constructed from PVC frames and covered with transparent plastic sheets were used to cage six vines within a vineyard row. Smoke was generated by burning Douglas fir pellets in a battery-operated grill and channeled into the chambers, with smoke treatments including an open-air control, a chamber control, and two levels of smoke treatments (low and high PM 2.5 at 1200 and 4000 µg/m3, respectively), to mimic typical concentrations recorded during low and moderate smoke years, converted over a two-hour period. A battery-operated mixing fan was installed inside each smoking chamber to distribute smoke evenly and regulate vine stomatal action. Smoke levels inside the chambers were monitored in real time using an air quality monitor and were regulated using valves attached to inlet tubes. Stable predetermined smoke concentrations were achieved inside chambers within 20 min of experiment initiation. Temperature and relative humidity inside the chambers were monitored in real time with sensors. This research highlights key technical challenges for simulating wildfire smoke events at a vineyard scale and demonstrates methods to achieve this goal.

Funding Support: USDA-NIFA-SCRI

Yaniv Lupo | Andrew McElrone | Luis Diaz-Garcia

Development of a High-Throughput Phenotyping Method to Assess Boron Tolerance for Breeding Programs

Yaniv Lupo,* Andrew McElrone, and Luis Diaz-Garcia
*University of California, Davis, Department of Viticulture and Enology, One Shields Avenue, Davis, CA, 95616 (ylupo@ucdavis.edu)

Boron serves as an essential micronutrient for plants, yet at elevated concentrations, it becomes toxic. In grapevines, boron toxicity triggers leaf senescence, reduces yield, and can ultimately lead to plant death. Among different grapevine species, there is variation in the ability to exclude boron from the shoots. This trait is a crucial component of boron tolerance and a valuable target for rootstock breeding. Our research leverages an extensive grapevine germplasm collection at the University of California, Davis, which includes wild Vitis species and breeding selections with natural variation in boron tolerance. Considering the low throughput and high costs associated with current methods for assessing boron tolerance, we are developing a new high-throughput phenotyping pipeline that integrates hyperspectral proximal sensing and machine learning modeling to predict boron content in different plant tissues. This method will significantly reduce the time required to identify grapevines with improved boron tolerance and eliminate the need for plant tissue collection. We will use this method to screen a large diversity panel genotyped with approximately one million molecular markers for genome-wide association mapping of boron tolerance traits and to identify genes responsible for boron exclusion. This research will provide insights into the adaptive mechanisms of grapevine boron tolerance and facilitate development of more resilient rootstocks for viticulture through the application of phenomics and molecular breeding.

Funding Support: Vaadia-BARD Postdoctoral Fellowship and University of California, Davis

Bronwyn Riddoch | Myroslava Khomik | Richard Petrone

Testing the Application of a Novel Technology for Assessing Grape Maturity using Spectrometry

Bronwyn Riddoch, Myroslava Khomik, and Richard Petrone*
*University of Waterloo, 200 University Ave W, N2L3G1, Canada
(rpetrone@uwaterloo.ca)

The Niagara region wine industry in Ontario, Canada, is already experiencing the effects of climate change, and more extreme weather events are expected. It is predicted that the changing climate will result in significant consequences for quality wine production. Consistent monitoring of grapes will help maximize their enological potential. However, most monitoring techniques are either destructive to the grapes or time-consuming (e.g., UAV flights). Past research on soft fruits and Chardonnay grapes suggests that the use of the visible light spectra can predict fruit/berry ripeness in a time-efficient and non-destructive manner.

PRecent advancements in compact and inexpensive technology for monitoring individual woody plant health and growth conditions, called TreeTalker, have been adapted to vines (TreeTalker Wine; TTW). This adapted technology allows continuous, real-time monitoring of grape status using spectrometry. Here, we present results from experiments that tested TTW’s ability to monitor grape veraison. We developed empirical relationships between spectral signatures measured by TTWs and berry total soluble solids (TSS) and investigated the possibility of using TTWs to predict berry TSS in situ and continuously on the vine until harvest.

Funding Support: Sources are University of Waterloo, Nature 4.0, and Ontario Grape and Wine Research Inc.

Initiation of a Three-Year Survey to Characterize the Distribution and Abundance of Nematodes in Oregon Vineyards

Ricky Clark, Cody Copp, Logan Bennett, Patricia Skinkis, Inga Zasada, and Alexander Levin*
*Oregon State University, Southern Oregon Research and Extension Center, 569 Hanley Rd, Central Point, OR, 97502 (alexander.levin@oregonstate.edu)

Winegrapes are an excellent host for numerous plant-parasitic nematodes and previous work has characterized nematode presence in Oregon vineyards. However, little work has been done to catalog the diversity of nematode species found in OR vineyards since the mid-1990s. The OR winegrape industry has expanded significantly since then, growing to nearly 45,000 acres. The cultivation of winegrapes now occurs on land with diverse usage histories ranging from forest and native pasture to former fruit and nut orchards. Therefore, this three-year survey was designed to identify the distribution and abundance of plant-parasitic nematodes across OR vineyards. The survey was started in the fall of 2023 and will continue through the spring of 2025 with the intention of capturing nematode diversity throughout the diverse viticultural geography of the state across three years. Samples will be taken from the predominant winegrowing areas of the state, including the North and South Willamette, Colombia, Rogue, and Umpqua regions. Fall 2023 samples were collected from 43 vineyard blocks across the state, distributed relative to planted acreage. Plant-parasitic nematodes were identified in 79% of surveyed vineyards blocks and in all five sampled regions of the state. Xiphinema spp. were identified in 51% of sampled blocks and in all five regions. Samples from the Colombia region yielded high abundance of Meloidogyne spp., due to the sandy soils. Samples from the Rogue region exhibited a high abundance of Mesocriconema spp., as they were present in 75% of vineyard blocks surveyed. This project aims to update and improve upon the previous statewide nematode survey from the mid-90s to provide better baseline information to the OR wine industry. The baseline data will benefit the industry by providing guidance for future studies on vineyard health and productivity, rootstock selection, and management of nematodes.

Funding Support: USDA-ARS Northwest Center for Small Fruits Research

Joseph DeShields | Achala KC | Alexander Levin

Mitigation of Grapevine Red Blotch Disease Effects using Potassium and Inducers of Plant Resistance

Joseph DeShields, Achala KC, and Alexander Levin*
*Oregon State University, 569 Hanley Rd, Central Point, Central Point, OR, 97502 (alexander.levin@oregonstate.edu)

Grapevine red blotch disease (GRBD), caused by the grapevine red blotch virus (GRBV), manifests foliar symptoms consisting of interveinal blotching on the leaves and is associated with reduced photosynthesis and carbon translocation, leading to lower sugar and anthocyanin levels in the fruit. Previous research established the mechanistic role that potassium (K) plays in facilitating sugar transport within the phloem. It has also been reported that GRBV-infected grapevines that are asymptomatic do not exhibit the same fruit quality reductions as symptomatic grapevines, suggesting that increased plant defense response could mitigate some of the effects caused by GRBD. Therefore, it was hypothesized that foliar- and/or soil-based applications of K and products that elicit systemic acquired resistance (SAR) or induced systemic resistance (ISR) may mitigate the fruit quality effects of GRBD. In 2023, two rates of soil-applied K and a single rate of foliar-applied K were evaluated using a split-plot design on GRBV-infected Cabernet franc and Merlot. In both cultivars, there was a significant effect of foliar K on total soluble solids (TSS; p = 0.046) and a significant effect of soil K on juice pH (p = 0.001), where increased foliar and soil K rates resulted in higher juice TSS and pH, respectively. In addition, a significant increase in sugar per berry was observed in response to increased soil-applied K in Merlot only. Two SAR/ISR products, Regalia and Actigard, were applied in a separate randomized complete block design on separate Cabernet franc vines. These products had a significant effect on yield (p = 0.032), with a 70% increase in Regalia-treated grapevines and an 18% decrease in Actigard-treated vines. Although some effects of K and plant resistance inducers were evidenced in this study, repeated evaluation over multiple years is necessary to understand the long-term effects of these treatments.

Funding Support: Oregon State University, Agriculture Research Foundation (OSU ARF)

Optimizing Biofungicide Use for Control of Grapevine Diseases on the Central Coast of California

Edgar Godoy-Monterroso,* Shunping Ding, Marco Fernandez, Quinn Cahoon, Shijian Zhuang, and Qun Sun
*Department of Viticulture and Enology, California Polytechnic State University-San Luis Obispo, Cal Poly 1 Grand Ave, San Luis Obispo, CA, 93407 (egodoymo@calpoly.edu)

Biofungicide efficacy in grapevine disease management is enhanced by selecting the right active ingredients and modes of action, optimizing application timing and understanding the pathogen’s biology, then integrating them properly into fungicide programs. The efficacy of biopesticides in vineyard production is influenced by local climate and environmental conditions. The objective of this study was to investigate the efficacy of biofungicides applied at different intervals in controlling powdery mildew and Botrytis bunch rot, and their effect on grape quality. The study was conducted in the San Luis Obispo Coast AVA on mature Chardonnay vines. Twelve fungicide programs were designed, with three biofungicides containing different active ingredients and modes of action, application intervals, and integration strategies. A grower-standard program and an untreated control were also included in the experiment. Fungicide applications started at bloom in May 2023 and finished at veraison in August 2023. Fungicide program efficacy was determined based on disease incidence and severity. Yield was measured by weighing all clusters from each plot. Berry chemistry (total soluble solids, pH, and titratable acidity) was assessed following standard laboratory protocols. Biofungicide active ingredient and mode of action significantly affected program efficacy, while the interval of application did not. All programs integrating biofungicides with synthetics had efficacy comparable to the grower standard which, with the exception of one biofungicide stand-alone program, resulted in significantly higher powdery mildew and Botrytis bunch rot disease control than biofungicide stand-alone programs. Yields were also significantly greater in these programs. This suggested that when designing a program with biofungicides in this AVA, integration with synthetics can significantly improve the efficacy of the programs. Berry chemistry was affected significantly by the fungicide program, but results did not necessarily correlate with their efficacy.

Funding Support: CDFA-Specialty Crop Black Grant Program and CSU ARI

Joy Hollingsworth | Karina Elfar | Tian Tian | Akif Eskalen

Summer Bunch Rot and Sour Rot Management on Table Grapes in the San Joaquin Valley

Joy Hollingsworth, Karina Elfar, Tian Tian, and Akif Eskalen*
*University of California, Davis, 1 Shields Ave, Davis, CA, 95616
(aeskalen@ucdavis.edu)

Sour rot (often known as summer bunch rot) is a disease complex that can be caused by multiple fungal species, including several Aspergillus spp., Botrytis cinerea, Cladosporium spp., Penicillium spp., and Rhizopus spp. or by yeasts, bacteria, and Drosophila flies. It is commonly found in the central and southern San Joaquin Valley of California due to the typically warm climate. Because this complex involves multiple causal organisms, it isn’t easy to control and multiple strategies are likely needed. To help determine the efficacy of disease control options, a field trial was conducted in two commercial table grape vineyards, in Delano on Red Globe and in Bakersfield on Autumn King, comparing seven spray treatments to an untreated control. Each treatment was replicated five times per site and sprays were repeated four times (bloom, pre-close, veraison, and preharvest) during the 2023 growing season. Shortly before harvest, each plot was evaluated for disease incidence and severity. A representative number of harvested bunches were stored in commercial cold storage (0°C, 90 to 95% RH) for five weeks, then rated for disease incidence and severity to determine the treatment efficacy during cold storage. Differences in natural disease pressure were observed between the two vineyards, with greater pressure in the Red Globe vineyard than in the Autumn King vineyard. The Elevate/Luna Experience/Switch/Vacciplant treatment was shown to be the most effective at reducing disease incidence in Autumn King, but there were no significant differences seen in Red Globe. After five weeks in cold storage, however, no product was significantly different from the control in incidence or severity in Autumn King, while the Pristine/Luna Experience/Elevate/Scala treatment resulted in significantly less incidence of infected bunches than the untreated control in Red Globe. Based on these findings, we plan to renew the project for another year to continue product evaluations.

Funding Support: California Table Grape Commission

Understanding the Mechanistic Basis of the Red Blotch Virus Infection for Better Disease Management

Bhaskar Bondada,* Marc Fuchs, Sadanand Dhekney, Benham Khatabi, Alexander Levin, and Patricia Skinkis
*Washington State University Tri-Cities, 2710 Crimson way, Richland, WA, 99354 (bbondada@wsu.edu)

Grapevine red blotch disease (GRBD), caused by Grapevine red blotch-associated virus (GRBaV), is a severe concern to grapegrowers and winemakers in major grapegrowing regions worldwide. One key aspect of all viruses, including GRBD, is their intimate association with cell components and anomalous structures following infection. This study aimed to analyze symptomatology, vine function, fruit quality, and ultrastructure of various tissues, and to document the relationship of ultrastructural cytopathology with GRBaV infection in Pinot noir, employing multiple microscopy techniques. The infected vines exhibited typical red blotches in leaves, with pinkish-red-colored veins, without rolling off the margins at the onset of ripening. The infected vines developed clusters of hens and chickens and altered seed morphology. Conversely, the healthy seeds were pyriform with a distinct beak. The infection significantly changed the composition of primary and secondary metabolites desired for making wine. Since postveraison berry development and ripening rely on phloem influx, the altered metabolism indicated disruption of the phloem pathway, either in the source leaf or in the berries. Furthermore, the infection modified the browning process, altering periderm formation in infected canes. Nonetheless, the infected green stem turned brown during the cold acclimation process. While the infected vines maintained primary leaf anatomical organization, their chloroplasts underwent significant ultrastructural changes, ranging from complete dismantling to massive accumulation of starch and plastoglobuli development in the chloroplasts and tannins in the cytoplasm. The results demonstrated that structural integrity is vital to maintaining normal metabolism of the grapevine, providing new insights into implementing innovative approaches for GRBD management.

Funding Support: Northwest Center for Small Fruits Research (NCSFR)

Eve Laroche-Pinel | Kaylah Rachel Vasquez | Luca Brillante

Advancing Vineyard Irrigation in the San Joaquin Valley, California, with Hyperspectral-Based Plant Water Status Mapping

Eve Laroche-Pinel, Kaylah Rachel Vasquez, and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)

Remote sensing has emerged as a valuable tool to enhance the precision of water supply budgeting using both spectral and spatial data. A study conducted in a Vitis vinifera L. cv. Cabernet Sauvignon vineyard in the San Joaquin Valley, California used a variable rate automated irrigation system across 12 distinct water regimes replicated in four randomized sets, resulting in 48 experimental zones. The primary objective of this experimental setup was to introduce variability in grapevine water status, facilitating the generation of a comprehensive data set for modeling purposes. Over the course of the growing season, spectral data within these zones were collected using a near infrared (NIR) – short wavelength infrared (SWIR) hyperspectral camera (ranging from 900 to 1700 nm) mounted on an unmanned aircraft vehicle. Given the significant water absorption characteristics within this spectral range, the sensor was deployed to evaluate grapevine stem water potential, Ψ_stem, a standard metric for assessing plant water status, from pure grapevine pixels in the hyperspectral images. Concurrently, Ψ_stem values were measured in the field from bunch closure to harvest and subsequently modeled using machine-learning techniques, leveraging the remotely sensed NIR-SWIR data as predictors in both regression and classification frameworks (with classes representing varying levels of physiological water stress). Hyperspectral images underwent conversion to bottom-of-atmosphere reflectance using standard ground panels and the quick atmospheric correction method, with ensuing results subjected to comparative analysis. The most effective models used ground panel-derived data and predicted Ψ_stem values with an R2 of 0.54 and an RMSE of 0.11 MPa, as estimated through cross-validation. Additionally, the optimal classification approach achieved an accuracy rate of 74%. This endeavor aims to pioneer novel methods for precise monitoring and management of irrigation in vineyards, while concurrently furnishing valuable insights into the physiological responses of plants to deficit irrigation practices.

Funding Support: American Vineyard Foundation, CSU-Agriculture Research Institute

Suraj Kar | Ricky W. Clark | Joseph B. DeShields | Ian Ivey | Alexander D. Levin

Establishing Baseline Data for Carbon Isotope Discrimination as an Effective Indicator of Rootstock Drought Tolerance

Suraj Kar, Ricky W. Clark, Joseph B. DeShields, Ian Ivey, and Alexander D. Levin*
*Oregon State University, Southern Oregon Research & Extension Center, 569 Hanley Road, Central Point, OR, 97502 (alexander.levin@oregonstate.edu)

Drought is an existential issue for growers across most American grape acreage and in grapegrowing regions throughout the world. Adaptation to drought therefore has always been a crucial consideration for growers. One strategy to manage grapevines under water-limiting conditions is to use drought-tolerant rootstocks. However, the grapevine rootstocks that are in use today were bred primarily for Phylloxera tolerance, so their drought responses have not been sufficiently examined. Plants, under drought stress, tend to discriminate against the lighter carbon isotope (C¹²) for the heavier one (C¹³) during photosynthetic carbon assimilation. This physiological trait – carbon isotope discrimination (δ¹³C) – has been used as a proxy for water status in grapevines. Therefore, this three-year-long research project was initiated to evaluate drought tolerance of 10 commonly-used rootstocks using δ³C, vine phenology, physiology (stomatal conductance [gsw] and stem water potential [Ψ_stem]), yield, and fruit quality (juice total soluble solids, pH, and titratable acidity [TA]) in a young, replicated field trial at the Southern Oregon Research and Extension Center in the Rogue Valley AVA. In the pilot year of the study (2023), all rootstocks were irrigated uniformly and baseline data were recorded. A significant rootstock effect was observed on phenology (budbreak, berry set, and veraison), gsw measured at veraison, vine yield, cluster weight, berries per cluster, and TA in the juice. In subsequent years of this trial, irrigation will be withheld from half of each experimental plot (scion-rootstock-block) postbloom. Under drought stress conditions, differences between rootstocks may be magnified and can be capitalized to highlight specific strengths and weaknesses of each genotype. Therefore, the main aim of this project, identification of drought-tolerant rootstocks and establishing selection and management criteria, will be satisfied at the end of this three-year-long field trial.

Funding Support: Oregon Wine Board (OWB), California Grape Rootstock Improvement Commission (CGRIC)

Ben-Min Chang | Brad Estergaard | Steve Marsh

Warmer but Longer Cold Air Exposure Can Hurt

Ben-Min Chang,* Brad Estergaard, and Steve Marsh
*Agriculture & Agri-Food Canada, 4200 Highway 97 S, Summerland, BC V0H 1Z0, Canada (ben-min.chang@agr.gc.ca)

Extreme cold events occurred in the Okanagan Valley, British Columbia, in December 2022 and January 2024. At Summerland Research and Development Centre, the lowest temperature reached -22.7°C in 2022 and -25.2°C in 2024. In 2022, grapevines were exposed to air temperature below -18°C for 42 hrs. In this area, the lethal temperature of buds was monitored regularly by differential thermal analysis. Before the 2022 cold snap, the lethal temperature to kill half of Merlot buds was -22.6°C in a commercial vineyard. The lowest temperature recorded was -21.5°C in the same area. With the known lethal and lowest temperatures recorded, the estimated bud damage rate was <50% at this site. However, the observed damage rate was 77%. This suggested that exposure time might be critical. The procedure of differential thermal analysis was modified to simulate 24 hrs exposure at -14, -16, -18, and -20°C. The canes were sampled from a Merlot vineyard in Summerland, BC in 2024 before the cold event and stored at 1 ± 3°C in a walk-in cooler until use. Forty buds were tested in each treatment. When the low temperature exotherm was detected, the timestamp was recorded simultaneously. After the 24 hrs treatment at constant temperature, the freezer temperature was ramped down to -33°C at a rate of 4°C/hr to kill all surviving buds. The cold hardiness of an additional 54 buds was also evaluated by the standard method. The results showed the lethal temperature was at -22.4°C measured by the standard method. However, six hours of exposure at -18°C was sufficient to damage 50% of the buds. The preliminary data suggests shorter exposure time is required at lower temperature to inflict bud damage. The exposure time should be considered when estimating bud damage rate.

Funding Support: Agriculture & Agri-Food Canada

Sam Dudley | Isaac K. Uyehara | Andrew McElrone | Megan K. Bartlett

Characterizing Root System Architecture Traits for Drought Tolerance in Grapevine Rootstocks

Sam Dudley,* Isaac K. Uyehara, Andrew McElrone, and Megan K. Bartlett
*University of California, Davis, 750 Anderson Rd., Davis, CA, 95616 (sdudley@ucdavis.edu)

To reduce the effects of climate change on viticulture, breeding more drought-tolerant rootstocks is a promising, but difficult, strategy due to limited information on traits and genes of interest. Our goal is to use an F1 population produced from a drought-tolerant and a drought-sensitive rootstock (110 Richter × 101-14 MGT) to identify molecular markers for root system architecture (RSA) traits in grapevine. Neutron radiography is an imaging technique that can non-destructively visualize entire small root systems. We subjected plants to two-week dry-down and rewatering treatments and used neutron radiography and new semi-automated root classification software to measure RSA. Here, we present preliminary results for a subset of 45 genotypes. We will complete measurements across the entire population and use genotyping by sequencing (GBS) to link RSA traits to molecular markers by next summer.

The 45 genotypes varied significantly (p < 0.001) in nearly all RSA traits, including total root length, mean root angle, aspect (total horizontal/vertical extent), root growth rate, and change in depth during drought. Roots were significantly steeper rooted and thicker in 110 Richter than 101-14 MGT, suggesting these are especially important traits for drought tolerance. Across genotypes, a more vertical aspect was correlated with a steeper root angle (r² = 0.47) and thicker mean root diameter (r² = 0.09), but independent of root system size and fibrosity (root system length/# of tips) (p > 0.05). Altogether, these findings suggest that this population is well-suited to identify genetic associations with RSA, and that selecting for a more vertical aspect, steeper root angles, and thicker roots could enhance drought tolerance in grape rootstocks, though more work is needed to evaluate how these phenotypes perform under field conditions. Genetic associations are pending current experimentation results.

Funding Support: California Department of Food and Agriculture

Santosh Kalauni | Roger Paul Schreiner | Patricia A. Skinkis

Evaluating Nitrogen, Potassium, and Magnesium Fertilization Effects on Vine Nutrient Status and Productivity in Western Oregon

Santosh Kalauni, Roger Paul Schreiner,* and Patricia A. Skinkis
*United States Department of Agriculture-ARS-HCRL, 3420 NW Orchard Ave, Corvallis, OR, 97330 (paul.schreiner@usda.gov)

Mineral nutrients play a crucial role in ensuring optimal vine growth and high-quality fruit production. This study investigates the effects of nitrogen (N), potassium (K), and magnesium (Mg) fertilization on vine nutrient status, productivity, and fruit composition in western Oregon vineyards over three years (2021 to 2023). Three trials were conducted: one focused on N in Chardonnay, while the other two addressed deficiencies of K and Mg in separate Pinot noir vineyards. Each trial had treatments replicated four times using a randomized block design. The N trial involved three rates of soil-applied N (no N, 20 lb N/acre, and 40 lb N/acre), while the K trial included both soil (no K, 200 lb K/acre, and 400 lb K/acre) and foliar fertilizer (3.3 lb K/acre) treatments. The Mg trial focused solely on foliar applications (no Mg, 3 lb Mg/acre, and 6 lb Mg/acre). Key findings revealed minimal effect of N on growth and fruit metrics, yet it positively influenced vine N status, with effects varying across different tissue types and over time. Additionally, juice yeast assimilable nitrogen levels increased as the N application rate increased. Notably, soil-based K application had more visible effects than foliar application or no K on vine growth; vine K status across leaf blade, petiole, and dormant stem; and juice pH by the end of the third year. The Mg trial had limited effects on vine growth and productivity, although leaf blade Mg increased with greater Mg application rates. Petioles did not respond significantly across the years. However, foliar Mg application reduced the severity of symptomatic leaves, particularly at high and medium application rates. These findings contribute to our understanding of nutrient management in western OR vineyards and are being used to establish critical nutrient levels tailored to specific grape varieties in the region and nationally as part of the High Resolution Vineyard Nutrition Project.

Funding Support: National Institute of Food and Agriculture-Specialty Crop Research Initiative Coordinated Agricultural Projects (CAP) grant project award number: 2020-51181-32159

Luis Ortiz, Luca Pallotti | Eve Laroche-Pinel | William Whalen | Luca Brillante

Enhancing Vine Resilience and Delaying Ripening: Novel Late-Season Practices for Grape Production in Central California

Luis Ortiz, Luca Pallotti, Eve Laroche-Pinel, William Whalen, and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno,
2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)

Global warming is significantly compromising grape production in regions like central California. Late-season practices aimed at reducing the efficiency of the photosynthetic apparatus might be the solution to improve vine resilience and delay ripening. In this trial, an untreated control © was compared with applications of pinolene (P) and diatomaceous earth (D). A fourth treatment involved shoot twisting (T), seeking to achieve the benefits of traditional topping by breaking xylem tissue without overexposing clusters. Leaf area, light interception, midday stem water potential, and gas exchange were measured over the 2023 season. Berry ripening was followed and grape production at harvest was evaluated. Twisting determined the desiccation of the upper portion of the shoot, reducing leaf surface while maintaining a low level of irradiance in the fruiting zone. Stem water potential results showed that D, and especially T, partly alleviated stress conditions, while P led to a worsened vine water status. D had the most pronounced effect on gas exchange, especially transpiration and stomatal conductance, thereby leading to higher water use efficiency trend in the treated vines. D and T fruit exhibited greater berry weights during the first half of the season, likely due to the improved water status, while P berries had reduced weight. All applied treatments significantly affected berry ripening, resulting in increased titratable acidity and lower must pH, without compromising crop yield at harvest.

This trial highlights that innovating traditional, easily mechanizable practices such as topping, and introducing new products like diatomaceous earth can be effective techniques to mitigate summer heat stress and delay berry ripening, particularly in hot, dry regions such as CA’s Central Valley.

Funding Support: N/A

Tian Tian | Joy Hollingsworth

Applications of Foliar Nutrients and Plant Growth Regulators can Improve Berry Firmness and Color in Red Table Grape

Tian Tian* and Joy Hollingsworth
*University of California Cooperative Extension, Kern County, 1031 S Mt Vernon Ave, Bakersfield, CA, 93307 (titian@ucanr.edu)

Tablegrape growers in the San Joaquin Valley, California face a significant challenge: berries of some red varieties lose firmness before harvest. This issue, known as preharvest fruit softening, has inflicted significant economic losses upon the CA table grape industry and appears to stem from disconnection between berry firmness decline and color development during ripening. Potential remedies include enhancing berry color development and extending the period during which berries maintain firmness after reaching maturity (18 to 19 Brix). In 2023, we evaluated whether cluster thinning, foliar nutrient applications (Ca, Mg, and orthosilicic acid), or foliar sprays of plant growth regulators (24-epibrassinolide, ethylene, and abscisic acid) could enhance berry firmness and color during ripening and ultimately increase marketable fruit at harvest. The trial was conducted in McFarland, CA in a Krissy vineyard that previously experienced preharvest fruit softening. We found that foliar sprays of Ca and Mg every two weeks from bloom to veraison resulted in firmer berries, but slower color development. Biweekly applications of orthosilicic acid during the same period improved berry color but had only minor effects on berry firmness. Applying 24-epibrassinolide at bloom, fruit set, and veraison increased berry firmness during ripening without affecting berry color. Application of ethylene with abscisic acid at veraison enhanced berry color, but compromised berry firmness. Cluster thinning at 10% at fruit set did not affect berry color or firmness. Neither foliar sprays nor cluster thinning altered harvestable yield and total yield at the first harvest. Due to an unexpected storm in late August and subsequent severe bunch rot, we were unable to collect more data. Even so, this study showed the potential of applying Ca and Mg, orthosilicic acid, and 24-epibrassinolide to mitigate preharvest fruit softening in red table grapes.

Funding Support: UC ANR and industry donation

Kanako Yanagisawa | Harumi Kikuchi | Fumiko Tanzawa | Kanako Sasaki

Identification of 2-methylisoborneol as an India Ink-Like Off-Flavor in Syrah (Vitis vinifera cv.) Wine

Kanako Yanagisawa, Harumi Kikuchi, Fumiko Tanzawa, and Kanako Sasaki*
*Kirin Holdings Company, Limited, 26-1-12-12 Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa, Shonan Health Innovation Park, 251-8555, Japan (Kanako_Sasaki@kirin.co.jp)

The objective of this study is to reveal the cause of an India ink-like off-flavor in Syrah berries and wine made from grapes grown in a vineyard in Japan in 2020 and 2021. Microbial contamination was suspected as the cause because this off-flavor was detected not only in wine, but also in Syrah berries. Thus, the study was conducted to identify the fungus and the specific flavor compound(s) responsible.

Grape berries collected during harvest, with a similar India ink-like odor, were used for this study. Fungi were isolated from these berries by rinsing the surface and culturing the rinse water on an agar medium. About 20 fungal strains were isolated and one released a strong India ink-like odor. This strain was identified as a Coniella spp., known as grape white rot fungus. Furthermore, we found that the Syrah berries infected with this strain released the India ink-like odor, while control berries did not. The aroma compounds of infected/non-infected berries were analyzed using the SIM/Scan mode of gas chromatography-mass spectrometry. These berries were incubated in a closed container and the odorous compounds were collected in a TENAX GC collection tube (P/N: 223-57102-91) by nitrogen purge. Several compounds were identified, such as fenchol, 2-methylisoborneol (MIB), and benzofuran, that are specific to the infected berries. It was considered that MIB is the candidate compound for the cause of this off-flavor because of its camphor-like odor.

The study concluded that the India ink-like off-flavor is caused by generation of MIB during infection by Coniella spp. This is the first report that Coniella spp. can produce MIB. These new insights are expected to contribute to production of high-quality grapes and wines.

Funding Support: Kirin Holdings Company, Limited

Diego Freire Bastidas | Alessandro De Rosa | Luca Brillante

Autonomous Identification of Grapevine Varieties in Sentinel 2 Satellite Imagery

Diego Freire Bastidas, Alessandro De Rosa, and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)

The development of new varieties has played a significant role in maintaining a strong and stable food supply. New plant varieties enable consumers to enjoy diverse, safe, nutritious, and abundant food and are protected under the Plant Variety Protection Act. The protection of intellectual property encourages continued investment in research and development and encourages bringing innovations to farmers to help them cope with changing conditions, from the climate to the markets. Protected plants can still be vegetatively propagated illegally. This undermines investment in research and development of new varieties and sustainable agricultural technologies.

This study aimed to investigate the ability of machine learning to identify grapevine varieties in Sentinel 2 satellite imagery. Our preliminary results, employing dimension reduction techniques alongside rigorous cross-validation, show an accuracy rate of >84% on >400 accessions within a single location. This accuracy underscores the efficacy of our approach in effectively discriminating among a diverse array of grapevine varieties present within the ranch.

Funding Support: N/A

Mitchell Davey | Danielle Fox | James Harbertson

Comparison of Freeze-Killed versus Freeze-Dried Leaves for the Production of Frost Tainted Cabernet Sauvignon Wines

Mitchell Davey, Danielle Fox, and James Harbertson*
*Washington State University, 2710 Crimson Way, Richland, WA, 99354-1671 (jfharbertson@wsu.edu)

A commercial freeze-dryer was used to emulate the effects of freeze-killed leaf material on Cabernet Sauvignon wines in 2023. Fresh leaves were collected from a vineyard in Sunnyside, WA one month prior to harvest, and freeze-killed leaves (FK) were collected at harvest. The fresh leaves were subjected to freeze-drying (FD). The FK and FD leaves were added directly to the must prior to fermentation at two rates (0.9 and 3.6 g/kg must) including a control (0 g/kg must). Basic wine chemistry was unaffected by the additions. Untargeted solid-phase microextraction gas chromatography-mass spectrometry was used to identify major aroma compounds present. Tentatively identified compounds were evaluated statistically. Twenty-three compounds were found to vary significantly based on the treatments. Alcohols were significantly reduced by both leaf treatments. Terpenoids and norisoprenoids significantly increased with increased leaf dosages. A previously-suggested frost taint marker, 6-methyl-5-hepten-2-ol, which smells like coriander was only found in the FK-treated wines. Esters significantly increased in both treatments, consistent with dosage. Phenolics were measured in the wines using the Adams-Harbertson assay. Counter to previous results, wines made with both FK and FD leaves had significantly more phenolics and anthocyanins were unaffected. With the exception of the single frost taint marker, the FD treatments emulated the FK-treated wines.

Funding Support: Washington Wine Commission

Charity Maosah | Tom Collins | James Harbertson

Use of Reverse Osmosis, Immobilized β-glucosidase, and Adsorption as Remedy for Smoke-Affected Wine

Charity Maosah*, Tom Collins and James Harbertson
*Washington State University, 1900 Stevens Dr., Apt 615, Richland, WA, 99354-2131 (charity.maosah@wsu.edu)

Every year, wine producing countries are affected by smoke from wildfires. Wine made from grapes that have been exposed to smoke from wildfires can have unpleasant burnt, leather, smoky, and other sensory attributes. Smoke-related volatile phenols that play a role in the smoky characteristics exist as free phenols and sugar-bound glycosides. Free volatile phenols contribute to smoky aromas in wine. After wine fermentation, acid-mediated hydrolysis can release bound phenols, leading to increased smoky aromas. To improve the quality of smoke-affected wines, both free and bound smoke-related phenols must be removed or reduced. There are no effective means to reduce both free and bound smoke phenols in affected wines. Use of reverse osmosis (RO) with solid phase adsorption reduces free-smoke related phenols but not bound-smoke related phenols. This can result in smoke recurrence after some time. This study evaluates the use of immobilized β-glucosidase to release bound-smoke related phenols in wine and permeate which can then be removed by RO and suitable adsorption technique. Smoke-affected wines were treated using RO to create a permeate containing the phenol glycosides. β-glucosidase was immobilized in cross-linked chitosan-silica microspheres. Both original wine and permeate were subjected to hydrolysis by immobilized β-glucosidase at different temperatures for four hours. Released volatile phenols can then be removed by adsorption using activated carbon. Enzyme hydrolysis of phenol-glycosides was dependent on sample type (wine or permeate), temperature, and incubation period. In both wine and permeate, 35°C had highest hydrolysis of phenol-glycosides (21.47% and 33.82%, respectively) with a high hydrolysis rate within the first two hours of incubation. This combination of immobilized enzyme with RO and adsorption can improve the quality of smoke-affected wines and greatly reduce losses incurred by grapegrowers in the case of wildfires.

Funding Support: USDA Washington State Wine Agricultural Research Service

Mariem Lamine | Paméla Nicolle | Aurélie Roland | Karine Pedneault

Effect of Cold Storage and Partial Grape Drying on Acidity and Aroma Precursors of Cold-Climate Interspecific Hybrids

Mariem Lamine, Paméla Nicolle, Aurélie Roland, and Karine Pedneault*
*Université du Québec en Outaouais, 78 rue Principale, Canada
(karine.pedneault@uqo.ca)

Nordic wine regions face challenges related to seasonal climate variations, including cold nights from late August onward that may affect berry ripening, preventing the breakdown of malic acid and hampering the accumulation of aroma precursors. With climate change, large climate fluctuations during the season further contributes to variable levels of ripening in northern vineyards. In Vitis vinifera, partial grape drying and cold storage have been shown to decrease the acid content of berries and increase their concentration in aroma precursors, including thiol precursors. Enological techniques to improve berry quality are understudied in interspecific hybrid grapes. In this experiment, we evaluated the effect of postharvest processes such as cold storage (10°C) and partial grape drying at two temperatures (20 and 30°C) on the organic acid and thiol precursor content of two white (St. Pepin, Frontenac blanc) and two red (Frontenac, Marquette) Vitis sp. varieties, during 12 and 24 days. Compared to berries prior to treatment, higher temperature (20, 35°C) lowered the titratable acidity (TA) in Frontenac, but not in Marquette. In contrast, cold storage increased TA in Marquette and St. Pepin. Only the highest temperature (35°C) decreased TA in Frontenac blanc and St. Pepin.

Aroma precursors are currently being analyzed so results will be available on the poster.

Funding Support: AAFC, CGCN, MITACS

Jedediah Fitzgerald | Zhi Wang | David Garcia | Robert Guzman | Qun Sun

Using Cover Crop to Mitigate the Effects of Winery Wastewater Application on Soil, Grape, and Wine Quality

Jedediah Fitzgerald, Zhi Wang, David Garcia, Robert Guzman, and Qun Sun*
*California State University, Fresno, 2360 E. Barstow Avenue, MS VR89, Fresno, CA, 93740 (qsun@mail.fresnostate.edu)

The San Joaquin Valley is facing drought and saline conditions, both of which have adverse effects on grapevine growth. Approximately 3000 to 5000 L wastewater are generated per metric tonne of crushed grapes annually, posing risks to vineyard soil physical and chemical properties, and ultimately affecting grape and wine quality. This study aims to examine the effects of cover crops on soil properties, determine the effect of cover crops on grape and wine quality, and promote effective water and soil management within the framework of sustainable viticulture.

Eight-year-old Ruby Cabernet vines from a commercial vineyard in Fresno, California were used for this study. The experimental design was a randomized complete block design with eight treatments replicated four times. The treatments were: a control (no-till with residential vegetation), tilled, UC 937 barley, WB patron wheat, Pacheco triticale, Sierra oats, rye grass, and Dairyland magnum salt alfalfa. Each experimental unit consisted of one vine row, a quarter-mile in length. The vineyard was furrow-irrigated with wastewater before planting the cover crop.

Results from the two years of the study revealed significant effects of cover crops on soil chemical compositions. Barley, oat, rye grass, triticale, and wheat sequestered carbon at higher levels (200 to 400 kg/acre) than the control. Oat, rye grass, triticale, and wheat absorbed nitrogen at higher levels (6 to 10 kg/acre) than the control. Barley and rye grass absorbed higher sodium content than the control. Triticale and wheat reduced soil electrical conductivity. Rye grass, triticale, and wheat resulted in lower soil sodium. Yield components exhibited no difference among treatments. However, preliminary wine sensory analysis has shown that the treatments may influence both aromatic properties and color. The project is ongoing and additional data will be provided after completion of the third-season trial.

Funding Support: Agricultural Research Institute (ARI)

Kanako Sasaki | Harumi Kikuchi

Evaluation of Ripe-Fruit-Like Aroma in Red Wines using an Automated Omission System

Kanako Sasaki* and Harumi Kikuchi
*Kirin Holdings Company, Limited, 26-1-12-12, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa, Japan (Kanako_Sasaki@kirin.co.jp)

Aroma is one of the most important criteria used to evaluate the quality of wine, and >1000 aroma compounds have been detected in wine. However, it is difficult to evaluate the combined effects of wine aromas originating from complex mixtures of volatile compounds, and to identify the key aroma compounds creating a specific nuance in the wine. An automated omission system was developed by Shimadzu Corporation to clarify the combined effects of multiple volatile compounds. As a configuration of the system, the gas sampling device and mass spectrometer are connected to divergent ends of the gas chromatography (GC) column. The volatile compounds in the injected samples are separated by GC and the targeted compound can be isolated to be analyzed by mass spectrometry, while the remaining compounds can be collected in a bag using the gas sampling device. The omission system allows us to evaluate whether the targeted compound is essential for total aroma nuance.

In this study, we verified whether this omission system can evaluate complex mixtures of volatile compounds in various types of red wine. At first, we evaluated the effect of ethyl hexanoate on the aroma of Muscat Bailey A wine, an indigenous grape cultivar in Japan. The volatile compounds in the wine were collected using the dynamic headspace method and injected into the omission system. Three sample bags were prepared: (1) one filled with all the volatile compounds of the wine, (2) one filled with all compounds but ethyl hexanoate, (3) one in which ethyl hexanoate was added back into bag 2. The results of sensory evaluation of these sample bags demonstrated that ethyl hexanoate was responsible for the “ripe-fruit-like aroma” in Muscat Bailey A wines. We will also report the impact of ethyl hexanoate on the aroma of two other wine varieties, Pinot noir and Cabernet Sauvignon.

Funding Support: Kirin Holdings Company, Limited

Surface-Enhanced Raman Spectroscopy for Quick Smoke Exposure Assessment

Alec Sobotka, Yanping Qian, Ye Feng, Taylor Krueger, Chong Fang, Steven Mayer, and Michael Qian*
*Oregon State University, 3051 SW Campus Way, Lab 244, Corvallis, OR, 97331 (michael.qian@oregonstate.edu)

Smoke exposure in grapes has become a major concern for the United States wine industry. Smoke exposure can lead to off-aromas with a smoky, ashy, and medicinal characteristic. When grapes are exposed to heavy smoke, volatile phenols and other volatile compounds are absorbed by the grapes and subsequently bind to the sugars to form glycosides. When the grapes are fermented, the off-aroma compounds are released from their bonded glycosides, contaminating the produced wine. The volatile phenols, including guaiacol; 4-methylguaiacol; and m-, o-, and p-cresol, are the most studied compounds related to smoke exposure. These compounds are typically analyzed by gas chromatography-mass spectrometry (GC-MS), providing information on smoke exposure and potential smoke taints. Due to the costly and time-consuming nature of GC-MS, we strove to find a more efficient method to quickly assess smoke exposure based on surface-enhanced Raman spectroscopy (SERS).

A Thermo Scientific Nicolet 6700 FT-IR / NXR FT-Raman spectrometer with a 785 nm laser was used to collect spectra. Raman spectra of volatile phenols were compared in synthetic wine. Silver nanoparticles were prepared in the lab and various silver and gold nanoparticles were obtained commercially. These nanoparticles were evaluated by SERS to enhance detection sensitivity. It was found that the commercially prepared gold nanoparticle strips can significantly enhance the absorption of guaiacol at 576 cm-1. Using gold nanoparticle strip SERS, guaiacol can be detected at 100 µg/L in synthetic wine. Further research is being conducted on authentic wines.

Funding Support: American Vineyard Foundation and Oregon Wine Board

Quinn Cahoon | Shunping Ding | Shijian Zhuang | Qun Sun

Effect of Biofungicides on Grape Quality, Composition, Fermentation, and Sensory Characteristics of Wines from California

Quinn Cahoon,* Shunping Ding, Shijian Zhuang, and Qun Sun
*Department of Viticulture and Enology, California State University Fresno, 5241 N Maple Ave, Fresno, CA, 93740 (qcahoon@mail.fresnostate.edu)

Synthetic fungicides have demonstrated adverse environmental effects on finished wine attributes. Alternatives such as biofungicides employ organisms to control pathogens. The purpose of this study is to assess the effects of biofungicides on grape and wine chemistry, fermentation, and wine sensory characteristics. Four separate grape crops treated with biofungicides were vinified: Pinot noir and Chardonnay from the Central Coast, and Carignan and Chardonnay from the San Joaquin Valley. Treatments consisted of three different biofungicides: two bacterial strains (Bacillus subtilis strain QST 713 and Streptomyces lydicus strain WYEC 108) and an extract of Reynoutria sachalinensis. Two controls consisted of synthetic fungicide applications and no fungicide. All treatments were carried out in quadruplicate. Data has been collected on fermentation and basic grape and wine chemical parameters (total soluble solids [TSS], pH, tiratable acidity, and ethanol). Preliminary results for the Central Coast indicate significant differences in TSS compared to untreated controls, while no significant differences were found in grape and wine chemical parameters for the San Joaquin trials. Preliminary sensory trials show differences in color and aromatic intensity between treatments. Further analyses will be conducted on the wine color, phenolic content using high-performance liquid chromatography, and sensory characteristics using descriptive sensory analysis.

Funding Support: CDFA, CSU-ARI

Effect of Soil and Foliar Nitrogen Applications on Syrah Fruit and Wine Tannin Concentration and Composition

Juliana Pazos, Ryan Doyle, Pierre Davadant, Nataliya Shcherbatyuk, Markus Keller, and James Harbertson*
*Washington State University, 2710 Crimson Way, Richland, WA, 99354-1671 (jfharbertson@wsu.edu)

Syrah fruit and wines from a Columbia Valley vineyard trial in Washington State were evaluated. Nitrogen was applied at four different rates: to early-season soil at 0, 22.5, 45, and 90 kg N/ha and at veraison foliar at 15 kg N/ha; these treatments were denoted as control, low, medium, and high N and urea. Treatments were applied to three different vine rows in a randomized block design in 2021 to 2023. Fifteen wines were made for each vintage (five treatments, three replicates). Fruit and wine anthocyanins, grape seed, and skin tannins were analyzed for concentration (2021 to 2023) using the Adams-Harbertson assay and composition using phloroglucinolysis (2022-2023). Phenolics were measured daily during fermentation and during aging. At harvest, N-containing compounds including ammonia, yeast available nitrogen (YAN), and protein were measured. YAN and ammonia increased in the high N and urea treatments, with some exceptions. No significant differences were found in seed tannin concentrations for the three vintages, and no clear pattern was observed for skin tannins or anthocyanins. However, wine tannin concentrations were significantly greater in the control than in the high-N application treatment in the 2021 vintage, and both the control and low treatments were significantly greater than the high and urea treatments in the 2022 and 2023 vintages. Protein concentration had the opposite trend, with higher juice protein concentrations in the medium, high, and urea treatments, although the measures varied considerably. The phloroglucinolysis results show no difference in fruit tannin size or composition; however, the high N and urea treatment wines had significantly smaller average polymer size. The results show that the vineyard N applications increased ammonia, YAN, and juice protein, but the increased protein may be responsible for the reduced tannin concentration and size observed in the high N and urea treatments.

Funding Support: USDA-NIFA SCRI, Washington Wine Commission, Washington State Grape and Wine Research Program, Ste. Micelle Wine Estates (in-kind)

Federico Casassa |Sean Kuster | Michael Upton | James Nelson | Bob Coleman

Chemical and Redox Potential Profiles of Assyrtiko Wines from California Fermented With and Without Solids

Federico Casassa,* Sean Kuster, Michael Upton, James Nelson, and Bob Coleman
*Wine and Viticulture Department, California Polytechnic State University San Luis Obispo (Cal Poly), 1 Grand Avenue, San Luis Obispo, CA, 93407 (lcasassa@calpoly.edu)

Assyrtiko grapes (20.1 Brix, pH 3.19, titratable acidity 8.5 g/L, liquid:solid ratio 9:1) from the Paso Robles AVA of California were made into wine following traditional white wine fermentation carried out either at cold (between 15 and 17°C, average 15.8°C; WF-C) or warm fermentation temperatures (between 19 and 26°C, average 20.7°C; WF-W) or in an orange wine style, i.e. in contact with fermentation solids (skins and seeds), also at cold (SF-C) or warm temperatures (SF-W). Final alcohol levels were lower in skin-fermented (~11% ABV) than in white-fermented wines (~11.9% ABV). The redox potential oscillated between -100 and -20 mV during the first four days of skin contact time, then reached up to 100 mV at the end of skin contact time in skin-fermented wines. Conversely, white fermentations showed consistent redox potentials in the -100 to -120 mV range, and as low as -160 mV. There was more acetaldehyde in wines that fermented cold, and were generally higher (36 mg/L) than acetaldehyde levels normally found in finished red wines. Tannins and total phenolics averaged 10 and 82 mg/L in WF wines, respectively, and 308 and 885 mg/L in SK wines, respectively, and were slightly higher in wines fermented warmer. As expected, wine color was 87% higher in SF wines. Assyrtiko wines made with skin fermentation had tannin and total phenolic profiles similar to those observed in Central Coast AVA Pinot noirs, although they did not produce polymeric pigments. This is the first time, to our knowledge, that the phenolic profile of skin-fermented Assyrtiko wines, a staple variety from Santorini (Greece), has been described. This work is part of a larger project aiming at assessing the winemaking potential of emerging varieties of Mediterranean origin in the Central Coast of CA.

Funding Support: Richard Lauchland (Duas Terras Vineyards, Paso Robles, California).

Olivia Jefferies | Thomas S. Collins | Elizabeth Tomasino

Effects of Sulfur Nutrient Additions on Thiol Concentration in Pinot noir

Olivia Jefferies,* Thomas S. Collins, and Elizabeth Tomasino
*Oregon State University, 1428 NW Highland Drive, Corvallis , OR, 97330 (olivia.jefferies@oregonstate.edu)

The wine industry is continuously threatened by the presence of wildfire smoke. Grapes exposed to smoke in the vineyard result in an ashy flavor in the finished wine. This flavor negatively affects wine quality, and in many cases, smoke-affected grapes are not made into wine. This can result in significant economic losses for the wine industry. Smoke-related compounds, thiophenols and volatile phenols, in combination cause the ashy flavor associated with grape smoke exposure. The formation of varietal thiols, important aroma compounds in Sauvignon blanc, has been researched extensively. An increase in sulfur-containing nutrients increases production of varietal thiols in Sauvignon blanc. We investigated whether adding sulfur-containing nutrients increases the concentration of smoke-related thiophenols during fermentation. In this study, smoke-exposed Pinot noir grapes from Oregon were made into wine using microferments. Different nutrient additions were added prior to yeast inoculation. Treatments included glutathione, glutastar, and diammonium phosphate (DAP). There were two controls: smoke-affected grapes with no nutrient additions and non-smoke-affected grapes with no nutrient additions. Free phenols were analyzed using GC-MS/MS; phenol-glycosides and thiols were analyzed using LC-MS/MS. The nutrient additions had no effect on the fermentation process, as all wines went through fermentation successfully. Results from this project are significant as they will provide another technique for winemakers to alleviate the effects of smoke exposure through varying nutrient additions during fermentation. Altering nutrients is an easy and inexpensive way for winemakers to manage this environmental issue.

Funding Support: USDA-ARS

Characteristic Extraction of Phenol Compounds in Koshu (Vitis vinifera cv.) Wine during Maceration

Daiki Kiyomichi, Hideki Takase, Kanako Sasaki, Gen Ikoma, Hironori Kobayashi, and Ryoji Takata*
*Kirin Holdings, Company, Limited, 26-1 Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa, Shonan Health Innovation Park 12-12, 251-8555, Japan (ryoji_takata@kirin.co.jp)

Koshu is an indigenous grape variety that has been grown in Japan for over a thousand years. Recent research showed that it has 70% Vitis vinifera genes. It is the most-cultivated variety for winemaking in Japan.

The variety is mainly used to produce white wines, including a skin-contact fermented white wine which is fermented with seeds and skin. There little known about the extraction of phenol compounds during fermentation and maceration of Koshu wine. Thus, the objective of this study is to reveal the character of skin-contact fermented white wine by examining its phenolic compounds.

In this study, Koshu was compared with other V. vinifera varieties, Sauvignon blanc (SB) and Merlot (MN). Fruit tissues were separeted into pulp, seed, and skin and soaked separately in model wine solution (12% ethanol, 3000 mg/L tartaric acid, pH 3.2) for 14 days to determine extraction of phenolic compounds. The results showed that proanthocyanidin was extracted from SB and MN seeds and its content increased during soaking. Proanthocyanidin was not extracted from Koshu seeds, despite the presence of proanthocyanidin. The three varieties were fermented with seeds and skin during 28 days to study the behavior of extraction of phenolic compounds during fermentation and maceration. The results showed that the content of proanthocyanidin in Koshu wine decreased dramatically during maceration. In contrast, that of SB and MN wine was stable or increased during maceration.

These new findings on the unique characteristics of proanthocyanidin in Koshu grape show the diversity of character in Vitis and contribute to the control of wine taste.

Funding Support: Kirin Holdings, Company, Limited

Exploring Dipeptides and Oligopeptides in Wine by UHPLC–HRMS

Liang Chen,* Xian Luo, Zhan Cheng, Shuang Zhao, Liang Li, and Gal Kreitman
*E & J Gallo Winery, 600 Yosemite Boulevard, Modesto, CA, 95354 (liang.chen@ejgallo.com)

Many dipeptides and oligopeptides identified in fermented foods and beverages have various taste-active or taste-modulating activities that encompass all five basic taste modes plus kokumi sensation. The presence of peptides in wine and their potential bioactivities and contributions to wine oxidative stability have been examined previously. However, the diversity of endogenous small peptides in wines remains unexplored. This study describes ultra high-performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) analysis of dipeptides and polypeptides in a range of commercial wines. Four Chardonnay wines produced at a commercial scale from vintage 2022 were screened and quantified for 400 common dipeptides by a previously developed chemical isotope labeling UHPLC Orbitrap HRMS approach. A total of 285 dipeptides were identified and quantified across all four wines at varied abundances. Dipeptide data was evaluated by principal component analysis, which showed clear and significant discrimination of wines. The most abundant dipeptides were in the wine that underwent malolactic fermentation, sur lie aging, and was aged in an oak barrel. No obvious correlation between individual amino acid and dipeptide was noted. In addition, untargeted peptidomic profiling based on UHPLC Orbitrap HRMS was developed and applied to a larger set of wines, including both commercial and experimental wines, for endogenous oligopeptides. Data-dependent acquisition HRMS spectra of non-tryptic wine samples showed the presence of large numbers of oligopeptides in wines. The peptide identifications were searched against literature peptide databases to screen sensory-relevant peptides. Salt-enhancing, bitter, sour, astringent, and kokumi peptides were found in the selected wines. The results presented in this study offer new insights on wine composition and pave the way for future study investigating the quality and sensory relevance of wine peptides.

Funding Support: E & J Gallo Winery

Sauvignon blanc Wine Protein Stability as Affected by pH Adjustment and Timing of Bentonite Addition

Wenfeng Hung, Roland Harrison, James Morton, Mike Trought, Andy Frost, and Bin Tian*
*Lincoln University, Ellesmere Junction Road, Lincoln, 7647, New Zealand (bin.tian@lincoln.ac.nz)

The effects of pH adjustments on Sauvignon blanc wine protein haze formation and the required amount of bentonite were investigated at both microscale and commercial scale, using identical juice. Additionally, three different timings for bentonite addition were examined during the pH adjustment trial: before, during, and after fermentation. The study used the hot and cold test to determine the bentonite requirement for protein stabilization. Wine proteins were analyzed using various techniques, including a modified Coomassie brilliant blue assay, lithium dodecyl sulfate polyacrylamide gel electrophoresis, and sodium dodecyl sulfate capillary gel electrophoresis. Findings revealed that lower juice pH levels (2.80 and 3.00) resulted in sluggish fermentation, while the presence or absence of bentonite during fermentation did not significantly alter fermentation kinetics at any pH level. Bentonite remaining in contact with ferment improved fermentation completion for the sluggish ferment (pH 2.80). Wines with lower pH exhibited reduced wine protein content and enhanced protein adsorption efficiency of bentonite fining, requiring lower bentonite dosages for stability. Bentonite addition during fermentation proved most effective in protein removal, while fining after fermentation required the least overall bentonite dosage. Although different fermentation scales minimally affected wine protein contents, they did not alter molecular weight (MW) profiles. The protein contents and MW profiles in stabilized wines were influenced by the original juice pH, displaying more complex patterns in high-pH juice.

Funding Support: Lincoln University

Bjarne Bartlett | Chris Curtin | C. Michael Sonza | Chris Curtin

How Many Strains of Brettanomyces are there? Integrating Global and Local Data Sets for Comprehensive Population Genomics

Bjarne Bartlett,* Chris Curtin, C. Michael Sonza, and Chris Curtin
*Oregon State University, Food Science and Technology, Wiegand Hall, SW Campus Way, Corvallis, OR, 97331 (bjarne.bartlett@oregonstate.edu)

Brettanomyces, best known for its significant economic impact upon the wine industry through spoilage of premium red wine, contributes to a range of fermentation processes worldwide. Previous studies have explored the genetic diversity of Brettanomyces isolates from wine and other sources, observing significant differences in properties with implications for wine spoilage potential. A notable example is sulfite tolerance, with tolerant isolates exhibiting similar genetic profiles found in several winemaking regions. Yet, these analyses remain fragmented due to their focus on different geographic origins and isolation sources, making it difficult to establish a clear picture of how many different populations, or strains, of Brettanomyces exist in association with a given source, such as wine.

Our research seeks to fill this gap by integrating several existing whole-genome sequence public data sets comprising 221 Brettanomyces isolates with data from our laboratory that spans a further 346 isolates. Our data also provides the first insights into Brettanomyces from Oregon’s Willamette Valley. The biogeographic patterns of Brettanomyces reflect a combination of natural dispersion, human-mediated transportation, and ecological adaptation. Through integrating this data, we seek to establish a definitive resource for Brettanomyces population genomics, shedding light on its varied effects on wine spoilage by geographic origin and environment. Importantly, we will use this resource to answer the question of how many strains of Brettanomyces there are, and how many are associated with wine.

Funding Support: USDA Agricultural Research Foundation Oregon Wine Board New Zealand Wine

Mary Riley | Justin Siegel | Anita Oberholster | David Mills

Enzymatic Degradation of Undesirable Phenols in Wines Contaminated by Brettanomyces or Smoke Taint

Mary Riley,* Justin Siegel, Anita Oberholster, and David Mills
*University of California, Davis, 1 Shields Ave, Davis, CA, 95616 (myriley@ucdavis.edu)

This is the first year of a multi-year project to discover and design enzymes with exclusive degradation of 4-ethylguaiacol (4EG) and 4-ethylphenol (4EP), the main sensory-active components in wine contaminated with Brettanomyces and responsible for a portion of the ‘taint’ phenols found in smoke-tainted wine (Figure 1). A library of 46 laccase enzymes were produced and tested in different buffered environments for activities on 4EG and 4EP, with multiple laccases degrading both phenols. All laccases were tested further in a model wine environment with 13% ethanol and tartaric acid, at pH 3.5. Multiple laccases quickly and completely degraded 4EG, along with mild activity on 4EP. Sequence analysis of the 4EG- and 4EP-active enzymes revealed two distinct clusters, each with a unique laccase that can degrade 100% of 4EG and 30% of 4EP in industrially relevant times, matrices, and concentrations. 4EP and 4EG docking interactions generated via computational modeling revealed the top-degrading laccases all display open active sites and likely contribute to activity on other, non-target, wine phenols, thereby reducing possible selective degradation of 4EG and 4EP. Currently, novel enzyme structures are being generated computationally to address this deficiency using open-source AI-tools, including RFDiffusion and LigandMPNN, with unprecedented abilities to design proteins and model their structures. The next phase of this project will use the knowledge of how laccases degrade 4EG and 4EP to create additional enzymes capable of fully, and exclusively, degrading the remaining smoke taint marker compounds including guaiacol, 4-methylguaiacol, o-, p-, and m-cresol, and syringol. The larger goal of this effort is to create a suite of novel enzymes that beneficially modulate wine flavor.

Funding Support: American Vineyard Foundation

Yanxin Lin | Misha Kwasniewski

Using In-Source LC-MS/MS Fragmentation to Fingerprint Tannin Structural Diversity and Protein Precipitation

Yanxin Lin and Misha Kwasniewski*
*Food Science Department, Penn State University, Penn State University, Rodney A. Erickson Food Science Building, State College, PA, 16803 (mtk5407@psu.edu)

Procyanidins (PCs), or condensed tannins, significantly influence the mouthfeel and stability of red wine and polyphenol-rich foods. However, current analytical methods sometimes fail to correlate perception of astringency or predict tannin retention properly. This may be partly because common analytical methods oversimplify phenolics or tannins into one value (e.g., total concentration), not accounting for their diverse structures and sizes. Additionally, precipitation by methylcellulose (MC) or bovine serum albumin (BSA) employs reagents that only partially resemble endogenous grape proteins or human saliva (HS). In relation to perception, HS is more appropriate for studying complexation with tannins, as it contains the actual proteins and quantities inducing in-mouth precipitation, rather than analogs. A rapid ultra-performance liquid chromatography-tandem mass spectrometry-based method, coupled with in-source fragmentation, was used to quantitatively analyze and fingerprint a wide array of PC structures in wine after precipitation with MC, BSA, and HS. PCs were first fragmented using three different cone voltages (CVs) in the ESI interface, then further fragmented in the collision cell to enable their selective detection using optimized MRMs, which are finally used in a model developed for sample characterization and creation of a tannin “fingerprint”. The “fingerprint” is composed of a variety of MRM transitions and their corresponding ratios for PCs across CVs, resulting in high-dimensional vectors for each PC rather than a single value, as seen in previous methods. Comparing “fingerprints” of PC standards to samples allows accurate identification and quantification of unknown PCs. Accuracy of the model was expressed as root mean squared error ranging from 0.0001 to 0.1475. Precision, expressed as relative standard deviation, was <0.82%. Within a one to five DP range of the “fingerprint”, HS removes more small oligomers and monomers than BSA and MC, suggesting potential underestimation of low molecular weight tannin effect on astringency by BSA and MC.

Funding Support: None

Megan Meharg | Mackenzie Aragon | Caroline Merrell | Tom Collins

Effect of Yeast Strain Selection on the Concentration of Smoke-Derived Volatile Phenols and Thiophenols in Wine

Megan Meharg, Mackenzie Aragon, Caroline Merrell, and Tom Collins*
*Washington State University, 359 University Dr, Richland, WA, 99354 (tom.collins@wsu.edu)

Wildfire and controlled burn events pose an economic threat to the global wine industry. Smoke-derived volatile phenols (VPs) exist as free and bound glycosidic precursors that are released during fermentation-driven enzymatic hydrolysis, but the role that yeast might play in thiophenol production has not been studied. Free VPs and thiophenols of smoke-affected wines have been shown to cause perception of undesirable attributes such as meaty, smoky, medicinal, and ashy aromas and flavors. Here we studied the effect of commercially available yeast strains on the concentrations of known smoke-derived VP and thiophenol markers. Grapevines (Vitis vinifera cv. Merlot) were experimentally exposed to smoke in a semi-controlled environment. Smoke-exposed and non-exposed grapes were fermented using 12 commercial yeast strains over two vintages. Gas chromatography-mass spectrometry confirmed the increased concentrations of VPs in wines from smoke-affected fruit compared to the control wines, but there were no differences in concentrations of VPs among the tested yeast strains. Investigation of thiophenols using high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry revealed differences between control and smoke wines in the relative peak area for thioanisole and thiophenol, but not for thiocresols or thioguaiacol. There were, however, differences among yeast strains for total thiocresols (m-, o-, and p-isomers) and for thioguaiacol. Our study suggests that commercial yeast strains play a role in the release of VPs and the concentration of thiophenols.

Funding Support: USDA, Washington Wine Commission, Jackson Family Wines.

Determining the Spoilage Potential of Brettanomyces Strains Isolated from Oregon Vineyards and Cellars

C. Michael Sonza, Emily Kaneshiro, Tess Snyder, Bjarne Bartlett, James Osborne, and Christopher Curtin*
*Department of Food Science and Technology, Oregon State University, 3051 SW Campus Way, Corvallis, OR, 97331 (christopher.curtin@oregonstate.edu)

Oregon wine producers can face economic losses from wine spoilage from Brettanomyces bruxellensis infections. Despite precautions to mitigate infections by B. bruxellensis, such infections still occur. Variation in mitigation efficacy may be due to the emergence of sulfite-tolerant strains of B. bruxellensis in the wine production facility, as well as differences in quantity and strain of B. bruxellensis on the grapes entering the winery. Limited knowledge exists regarding whether known or novel sulfite-tolerant strains are present in OR wine facilities. Furthermore, the extent to which B. bruxellensis exists in vineyards is not well characterized due to the difficulty of isolating this yeast when more-abundant background yeast are present. This study seeks to address the limited understanding of the spoilage potential of B. bruxellensis strains found in OR cellars and vineyards.

We collected 100 Pinot noir cluster samples during the 2023 harvest from five different OR vineyards and will use an additional 105 cluster samples cryopreserved from the 2022 harvest. Collected vineyard samples will be grown in a selective enrichment medium that is currently being optimized to preferentially grow B. bruxellensis and limit background yeast growth. We also collected 52 wine samples and 79 environmental swabs representing seven OR cellars. Any identified B. bruxellensis isolates from the vineyard and cellar will be whole-genome sequenced and evaluated with sequence alignment to determine how related OR strains are to known strains outside of OR, particularly sulfite-tolerant strains. A preliminary enrichment formulation trial using cellobiose as the sole carbon source shows promising inhibition of background yeast, while not impeding growth of most B. bruxellensis isolates. The outcomes of this study will clarify the spoilage capacity of B. bruxellensis in OR wineries and vineyards, supporting wine producers to make informed decisions on how to best protect their wine from infections.

Funding Support: Oregon Wine Board

Jonathan Brumley, | Ipek Aktuna | Charles Edwards

Impact of Yeast Assimilable Nitrogen and Sugar on Sequential Fermentation with Metschnikowia pulcherrima and Saccharomyces cerevisiae

Jonathan Brumley,* Ipek Aktuna, and Charles Edwards
*Washington State University, 1455 NE Brandi Way LL-303, Pullman, WA, 99163 (jonathan.brumley@wsu.edu)

We investigated the application of a low ethanol-producing yeast during co-fermentation with Saccharomyces cerevisiae to lower alcohol concentrations in wine. Specifically, this study investigated the complex relationships between yeast assimilable nitrogen (YAN) and sugar concentrations on Metschnikowia pulcherrima in sequential fermentation. A two × three factorial was designed, with YAN (40 mg N/L or 280 mg N/L) and soluble solids (24, 27, or 30 Brix) as variables, by modification of synthetic grape juice media (SGJM). SGJM was fermented by either S. cerevisiae alone, or by M. pulcherrima and S. cerevisiae, the latter inoculated on day 4. Fermentations inoculated with M. pulcherrima reached similar maximum populations (≈107 CFU/mL), except for those containing 40 mg N/L at 30 Brix, where populations were only 106 CFU/mL. In general, M. pulcherrima exhibited an extended lag phase before log growth in media containing 30 Brix, regardless of initial YAN concentrations. All fermentations with 40 mg N/L progressed slower than fermentations with 280 mg N/L. Low YAN fermentations only reached dryness (completion) at 24 Brix, which occurred six days after high-YAN fermentations at the same sugar level. SGJM fermented with M. pulcherrima and S. cerevisiae had lower glycerol concentrations than single-inoculation fermentations in 27 and 30 Brix treatments. Contrary to previous studies, ethanol concentrations were not affected by the presence of M. pulcherrima, except for the treatment containing 40 mg N/L with 24 Brix, which resulted in 0.7% v/v reduction.

uigi Picariello | Maria Tiziana Lisanti | Alessandra Luciano | Angelita Gambuti

Dissolved Oxygen Removal in Wines by Membrane Contactor and Nitrogen Sparging

Luigi Picariello, Maria Tiziana Lisanti, Alessandra Luciano, and Angelita Gambuti*
*University of Naples Federico II, Viale Italia 60, Avellino, 83100, Italy (angelita.gambuti@unina.it)

Many enological practices can result in excess dissolved oxygen in wine, leading to sensory and chromatic defects over time. Effective management of O₂ levels before bottling is crucial. This study employed nitrogen sparging and a polypropylene hollow fiber membrane contactor apparatus to regulate dissolved O₂ in wines derived from two grape varieties, Aglianico and Greco. Dissolved O₂ levels were monitored during treatments, with all treated wines achieving levels <1 mg/L. Phenolic compounds and acetaldehyde were assessed using high-performance liquid chromatography, volatile compounds were determined via gas chromatography-mass spectrometry, and chromatic characteristics were evaluated using spectrophotometric methods. Analyses were conducted immediately after treatment and after six months of aging under controlled O₂ conditions. Following aging, both Aglianico and Greco treated wines had less acetaldehyde content and higher levels of free and total SO₂ than control wines. However, no significant differences were detected between N sparging and membrane contactor treatment for the other parameters evaluated.

Funding Support: Italian Ministry of University and Research PRIN 2022 PNRR P2022H573K

Ezekiel R. Warren | Misha T. Kwasniewski | Ryan J. Elias

Characterization of Polyphenol Elongation Induced by Exogenous Acetaldehyde

Ezekiel R. Warren, Misha T. Kwasniewski,* and Ryan J. Elias
*The Pennsylvania State University, Rodney A. Erickson Food Science Building, State College, PA, 16803 (mtk5407@psu.edu)

Small amounts of oxygen are consumed during red wine aging, causing a cascade of reactions resulting in polyphenol elongation. The actual elongation is induced by acetaldehyde, an oxidation product of ethanol, creating ethylidene bridges between polyphenols. Elongation decreases bitterness and astringency while increasing color stability. Natural ingress of O₂ can cause other unwanted reactions and off-flavors depending on the stability of the wine and, in extreme cases, may even facilitate the growth of Acetobacter sp. It has been previously demonstrated that the direct addition of acetaldehyde can be added postfermentation to induce elongation, while avoiding excess dissolved O₂. To further study this reaction and the products produced, exogenous acetaldehyde was added to model wine (12.5% EtOH, 250 mg/L catechin, pH 3.5) at 0, 50, and 250 mg/L, at two temperatures (4° and 35°C) with and without SO₂. Solutions were sampled over 21 days, monitored using a liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based method developed with multiple-reaction monitoring for ethylidene bridged catechins. Increasing temperature and acetaldehyde concentration increased the rate at which products were formed. Sequential addition of acetaldehyde instead of one large addition did not result in an ultimate difference in elongation products. Additionally, the addition of SO₂ at 250 mg/L did not fully inhibit elongation, indicating this reaction can proceed even in the presence of free SO₂, though at a decreased rate. To further characterize products formed, isotopically labeled acetaldehyde-d4 was reacted with catechin. Using a metabolomics workflow, ions produced from adding acetaldehyde and acetaldehyde-d4 were identified, showing the production of many more products than had been identified previously. Further investigations of this type were conducted with a mixture of catechin, procyanidin B2, and malvidin-3-O-glucoside. Acetaldehyde was added to Cabernet Sauvignon wine and the same ions were observed through LC-MS/MS. Ultimately, this research could give a new tool for winemakers to enhance their wine.

Funding Support: Pennsylvania Liquor Control Board

Amanda Fleming | Renee Threlfall

Assessing Color and Phenolics of Wines Produced from Co-fermentation of Vitis rotundifolia and Vitis vinifera Grapes

Amanda Fleming and Renee Threlfall*
*University of Arkansas System Division of Agriculture, 2650 N. Young Ave, Fayetteville, AR, 72704 (rthrelf@uark.edu)

While Vitis vinifera grapes are used predominantly for wine production, muscadine grapes (Vitis rotundifolia Michx.), native to the southeast United States, are also used but can have issues with color and phenolic stability. Cofermentation, two or more grape varieties fermented together, can enhance wine phenolic stability. Furthermore, sulfur dioxide (SO₂) additions in wines can affect color. In 2023, Noble (Vitis muscadinia) and Merlot (V. vinifera) grapes were harvested from commercial vineyards, randomized into five cofermentation treatments in duplicate (100% Noble; 75% Noble + 25% Merlot; 50% Noble + 50% Merlot; 25% Noble + 75% Merlot; and 100% Merlot), processed, and fermented. At bottling, SO₂ was added to each cofermentation treatment at different molecular levels (0.0, 0.8 and 1.5 mg/L). At bottling, wine pH (3.24 to 3.67), titratable acidity (0.60 to 0.80%), free SO₂ (18.53 to 42.43 mg/L), and ethanol (10.35 to 13.64%) varied for each cofermentation treatment. The cofermentation × SO₂ interaction was significant for L*; 100% Noble without SO₂ had the lowest L* and 100% Merlot with 1.5 mg/L SO₂ had the highest. As Noble increased in each cofermentation treatment, red color, brown color, color density, total phenolics, and total anthocyanins increased. Wines without SO₂ had more red and brown color and greater color density than wines with 0.8 or 1.5 mg/L SO₂. Wines with 100% Noble had the highest total phenolics (2037 mg gallic acid/L) and total anthocyanins (1712 mg/L) compared to 100% Merlot (884 mg gallic acid/L and 296 mg/L, respectively). At bottling, wines with ≥25% Noble had higher color and phenolic content than 100% Merlot wines. Furthermore, SO₂ had more effect on L* in cofermentation treatments with more Merlot than Noble. Blends with more Merlot had more SO₂ bleaching, with lower phenolic and color content at bottling, while wines cofermented primarily with Noble grapes had darker color and more phenolics at bottling.

Funding Support: Southern Region Small Fruit Consortium Grant

Genome-Wide Association Study of Anthocyanins and Phenolics in a Cold Climate Winegrape (Vitis spp.) Population

Rajasekharreddy Bhoomireddy,* Ramesh Pilli, Venkateswararao Kadium, Brent Trela, Collin Auwarter, Andrej Svyantek, and Harlene Hatterman-Valenti
*North Dakota State University, 1844 10th St N, Fargo, ND, 58105 (r.bhoomireddy@ndsu.edu)

To ensure superior wine quality and enhanced health benefits, it is desirable to maintain stability of anthocyanins and total phenolics in winegrapes. These compounds not only impart rich color and robust flavor to wine, but also include antioxidants that are beneficial to human health. However, ensuring their stability poses a significant challenge in North Dakota’s harsh and variable climate. Deciphering genetic control of these compounds is crucial to influence the astringency, color, and mouthfeel of the wine. An incomplete diallel population of 1064 individuals was used to examine the genetic basis of key compounds for total phenolic and anthocyanin composition that affect both health benefits and sensory attributes of wine. To understand the genetic variation responsible for these traits, a genome-wide association study (GWAS) was conducted using 24,000 SNP markers. The GWAS revealed six significant SNP associations for anthocyanins on chromosomes 2, 5, 7, and 16 and three significant SNP associations for total phenolics on chromosomes 2, 6, and 11 over a period of two years. These findings will provide insights to understand the genetic factors affecting phenolic and flavonoid levels in winegrapes, offering a valuable resource for viticulture and enology, with potential applications for grapevine breeding for improved wine quality.

Funding Support: Specialty Grant

Correlating Volatile Phenol Concentrations in Cabernet Sauvignon Grapes to Unfavorable Sensory Characteristics in Wines

Bainian Chen, Arran Rumbaugh,* Ron Runnebaum, Chen Liang, Annegret Cantu, and Hildegarde Heymann
*USDA-ARS, 595 Hilgard Lane, RMI North, room 3156, Davis, CA, 95616 (arran.rumbaugh@usda.gov)

Within California’s wine industry, wildfire smoke poses a significant threat to vineyards by imparting negative sensory attributes to wines, termed “smoke taint.” Hence, predicting the emergence of such tainted wines is crucial. This study evaluated the efficacy of a proof-of-concept approach to reproducibly expose grapes to smoke conditions. The long-term aim is to establish threshold levels of smoke-derived compounds in grapes that cause negative sensory attributes in the final wines. Around 250 kg of Cabernet Sauvignon grapes was harvested at 25 Brix from the Tyree vineyard at the University of California, Davis. Four experimental groups were exposed to various levels of smoke generated from red oak chips: control-exposure (CE, no smoke exposure), low exposure (LE, 0.5-hr exposure), medium exposure (ME, two-hr exposure), and high exposure (HE, four-hr exposure). Each experiment was conducted in an in-house constructed smoking chamber. Following smoke exposure, duplicate fermentations of each treatment were performed in stainless steel buckets. Volatile phenols (VPs) and their glycoconjugates (bound) were measured in grape and wine samples using gas chromatography-tandem mass spectrometry and liquid chromatography-tandem mass spectrometry, respectively. In addition, sensory differences in wines were determined utilizing descriptive analysis (DA). Free and bound VP concentrations in grapes and wines correlated positively with smoke exposure duration and intensity, as expected. Results indicated no significant sensory differences between LE and CE wines. ME samples were described as “medicinal” and significantly lower in fruity aroma than LE and CE samples. HE samples were rated even lower in fruity aromas and higher in “barbeque” and “ashy” aromas than all other treatments. Overall, ME wines had a significant sensory affect compared to CE wines, suggesting a potential range for future threshold experiments. The study was a successful proof-of-concept to develop threshold levels of free and bound VPs in grapes that will lead to unfavorable sensory attributes in the final wines.

Funding Support: USDA-ARS Funded Research

Correlating Volatile Phenol Concentrations in Cabernet Sauvignon Grapes to Unfavorable Sensory Characteristics in Wines

Bainian Chen, Arran Rumbaugh,* Ron Runnebaum, Chen Liang, Annegret Cantu, and Hildegarde Heymann
*USDA-ARS, 595 Hilgard Lane, RMI North, room 3156, Davis, CA, 95616 (arran.rumbaugh@usda.gov)

Within California’s wine industry, wildfire smoke poses a significant threat to vineyards by imparting negative sensory attributes to wines, termed “smoke taint.” Hence, predicting the emergence of such tainted wines is crucial. This study evaluated the efficacy of a proof-of-concept approach to reproducibly expose grapes to smoke conditions. The long-term aim is to establish threshold levels of smoke-derived compounds in grapes that cause negative sensory attributes in the final wines. Around 250 kg of Cabernet Sauvignon grapes was harvested at 25 Brix from the Tyree vineyard at the University of California, Davis. Four experimental groups were exposed to various levels of smoke generated from red oak chips: control-exposure (CE, no smoke exposure), low exposure (LE, 0.5-hr exposure), medium exposure (ME, two-hr exposure), and high exposure (HE, four-hr exposure). Each experiment was conducted in an in-house constructed smoking chamber. Following smoke exposure, duplicate fermentations of each treatment were performed in stainless steel buckets. Volatile phenols (VPs) and their glycoconjugates (bound) were measured in grape and wine samples using gas chromatography-tandem mass spectrometry and liquid chromatography-tandem mass spectrometry, respectively. In addition, sensory differences in wines were determined utilizing descriptive analysis (DA). Free and bound VP concentrations in grapes and wines correlated positively with smoke exposure duration and intensity, as expected. Results indicated no significant sensory differences between LE and CE wines. ME samples were described as “medicinal” and significantly lower in fruity aroma than LE and CE samples. HE samples were rated even lower in fruity aromas and higher in “barbeque” and “ashy” aromas than all other treatments. Overall, ME wines had a significant sensory affect compared to CE wines, suggesting a potential range for future threshold experiments. The study was a successful proof-of-concept to develop threshold levels of free and bound VPs in grapes that will lead to unfavorable sensory attributes in the final wines.

Funding Support: USDA-ARS Funded Research

Calcium Tartrate: New Assessment Method and Management of Instability

Florencia Cremades, Gianni Triulzi, Giorgia Quinterno, Alessandra Basana, Barbara Scotti, and Lorenza Allen*
*Enartis, 7795 Bell Road, Windsor, CA, 95492 (lorenza.allen@enartis.com)

The study addresses the critical challenge of calcium tartrate precipitation in white and rosé wines, an issue exacerbated by climate change. Due to the complexity of the processes involved in this phenomenon, there was no easily applied method available to define calcium tartrate instability. Research from Enartis introduces a groundbreaking evaluation method to obtain calcium tartrate stability, incorporating a comprehensive analysis of the effect of wine pH on tartaric acid dissociation and calcium tartrate formation. This new stability test for calcium tartrate provides more accurate prediction of potential instability.

The research also explores an innovative treatment strategy for wines exhibiting calcium instability. This involves the application of micronized calcium tartrate, proving its efficacy in reducing calcium concentration and enhancing wine stability. This approach to managing calcium tartrate stability was successful, confirming both the accuracy of the new test and the efficacy of micronized calcium tartrate in stabilizing solutions. This research marks a significant advancement in the wine industry’s ability to predict and manage calcium tartrate instability, offering practical solutions for winemakers grappling with the implications of climate change on wine quality.

Funding Support: Enartis

Jacob Martin | Bjarne Bartlett | Chris Curtin

Relevance of Nitrate Assimilation by Brettanomyces bruxellensis in Low-Nitrogen Environments

Jacob Martin, Bjarne Bartlett, and Chris Curtin*
*Oregon State University, Department of Food Science and Technology, Wiegand Hall, SW Campus Way, Corvallis, OR, 97331 (christopher.curtin@oregonstate.edu)

Brettanomyces bruxellensis possesses the rare (among yeast) ability to assimilate nitrate, which confers sufficient advantage for it to outcompete Saccharomyces cerevisiae in fermentation processes enriched in nitrate, such as fermentation of sugarcane for bioethanol. When nitrate is abundant, B. bruxellensis can grow and ferment more rapidly under anaerobic conditions, through reversal of the Custers’ effect and concurrent acetate production. Surprisingly, some B. bruxellensis strains cannot use nitrate due to structural gene deletions. Could this be due to lack of advantage in environments with low nitrate concentrations?

Genomes of 189 B. bruxellensis strains were analyzed for the presence/absence of nitrate assimilation genes, with 13 strains displaying at least partial deletion within the structural gene cluster. Previous studies showed loss-of-heterozygosity (LOH) events across this cluster, that may have some effect on phenotype. We found a high proportion of strains with LOH (68%) that varied with regard to the initiation of LOH from 0 to 10 kb upstream of the cluster. We are currently evaluating association of deletion and LOH events with different B. bruxellensis populations, and correlation with growth on nitrate.

To evaluate the relevance of nitrate assimilation during fermentation in low-nitrate environments, one strain that displayed stronger growth on solid medium with nitrate was selected. Preliminary experiments in anaerobic environments show this strain used significantly more glucose (p = 2^e-16) and produced more acetic acid (p = 2^e-16) when grown on nitrate than ammonium, even at relatively low concentrations (0.042 g/L) of nitrogen.

Funding Support: Agricultural Research Foundation

David Spector | Duncan Hamm

Exploring the Synergistic Effects of Lactobacillus plantarum and Oenococcus oeni in Malolactic Fermentation

David Spector and Duncan Hamm*
*Chr. Hansen, 9015 W. Maple, Milwaukee, WI, 08406 (davsp@novonesis.com)

The intricate dance of malolactic fermentation (MLF) in winemaking significantly influences wine quality, offering a playground for synergistic interactions between Lactobacillus plantarum (LP) and Oenococcus oeni (OO). This study examines the co-inoculation of LP and OO and their collaborative effect on MLF efficiency, bioactive peptide (bioP) production, and flavor development across different pH conditions. Using a refined experimental blend, we used lab-scale screenings and fermentation trials in must, providing insights into acetic acid production and the influence on wine sensory attributes. Preliminary findings suggest that strategic use of LP and OO not only expedites MLF completion, but also enhances a wine’s organoleptic properties, establishing a compelling case for their combined use in modern enology. This abstract presents data from extensive trials, including modified inoculation strategies and the evaluation of acetic acid levels, illustrating the potential of these microbial partners to revolutionize winemaking practices.

Funding Support: Chr. Hansen

David Spector | Duncan Hamm | Katja Sander Jensen

Comparative Analysis of Glutathione Production by Commercial Non-Saccharomyces Yeast Strains in Wine Fermentation

David Spector, Duncan Hamm,* and Katja Sander Jensen
*Novonesis A/S, Boege Alle 10-12, Hoersholm 2970, Denmark
(dunha@novonesis.com)

L-γ-glutamyl-L-cystinyl-glycine, commonly known as glutathione (GSH), plays a crucial role as an antioxidant in wine, helping to mitigate the loss of volatile flavor compounds susceptible to oxidation, as well as preventing oxidative browning and aroma changes. In recent years, particular interest in using GSH in winemaking has developed and as a result, yeast derivatives rich in this compound have been marketed to maximize and preserve flavor expression. Non-Saccharomyces yeasts (NSY) have been associated with producing higher concentrations of GSH than Saccharomyces cerevisiae, yet data on the production of this compound across different species or strains is limited.

This work investigates the potential of four commercial NSY strains from three species—Lachancea thermotolerans, Pichia kluyveri, and Torulaspora delbrueckii—to increase the GSH concentration in the final wine. Assessments will be conducted in two musts designed to emulate conditions for red and white or rosé wine fermentations, respectively. The initial yeast inoculation will take place with NSY before S. cerevisiae is inoculated 48 hours later.

Preliminary findings suggest that the non-Saccharomyces yeast strains exhibit varied capabilities in enhancing GSH levels, potentially offering winemakers new tools to improve wine quality and stability through natural antioxidant mechanisms. Further research and trials will illuminate the practical implications of these findings for winemaking practices, particularly for flavor preservation and oxidative stability.

Funding Support: Novonesis A/S (formerly Chr. Hansen A/S)

Natural Cork Classification Based on Oxygen Transmission Rate

Gonçalo M. Guedes, Ana Filipa L. O. M. Santos, Diogo P. Oliveira, C. Mariana Machado, Ana C. Lopes Cardoso, and António César S. Ferreira*
*Cork Supply Portugal, S.A. Rua Nova do Fial, 102, 4535-465 São Paio de Oleiros, Portugal (aferreira@corksupply.pt)

Managing oxygen exposure is a crucial and complex aspect of winemaking, affecting every stage from initial juice extraction to maturation. The amount of O² to which wine is exposed significantly influences its taste, aroma, and overall quality. In particular, white wines can suffer from premature oxidation during bottle aging, which deteriorates their sensory quality—a problem recognized since the 1990s, initially through changes in wine color. Research has since divided into two main paths: exploring how oxidation affects sensory perceptions and investigating the molecular mechanisms behind it.

The factors influencing oxidation in bottled wine include the wine’s composition and antioxidant content, the presence of transition metals like iron and copper, the bottling process, variability in bottle necks, treatments at the cork-glass interface, and the O² transmission rate (OTR) through the cork. These factors are influenced by storage conditions such as time, temperature, pH, and bottle orientation.

To tackle the variability in OTR of natural cork stoppers, a new process has been introduced into production lines. This process uses advanced imaging and deep learning to analyze the internal structure of corks and correlate it with their OTR, effectively distinguishing corks with high OTR from the standard range. This allows for real-time sorting of corks during manufacturing, ensuring that only those with suitable OTR values are used, thereby enhancing the consistency and quality of wine by minimizing undesirable oxidation effects. This method has been validated through established OTR measurement techniques (UVAMOX, Spain).

Funding Support: Cork Supply Portugal, S.A

Natural Cork Classification Based on Oxygen Transmission Rate

Gonçalo M. Guedes, Ana Filipa L. O. M. Santos, Diogo P. Oliveira, C. Mariana Machado, Ana C. Lopes Cardoso, and António César S. Ferreira*
*Cork Supply Portugal, S.A. Rua Nova do Fial, 102, 4535-465 São Paio de Oleiros, Portugal (aferreira@corksupply.pt)

Managing oxygen exposure is a crucial and complex aspect of winemaking, affecting every stage from initial juice extraction to maturation. The amount of O² to which wine is exposed significantly influences its taste, aroma, and overall quality. In particular, white wines can suffer from premature oxidation during bottle aging, which deteriorates their sensory quality—a problem recognized since the 1990s, initially through changes in wine color. Research has since divided into two main paths: exploring how oxidation affects sensory perceptions and investigating the molecular mechanisms behind it.

The factors influencing oxidation in bottled wine include the wine’s composition and antioxidant content, the presence of transition metals like iron and copper, the bottling process, variability in bottle necks, treatments at the cork-glass interface, and the O² transmission rate (OTR) through the cork. These factors are influenced by storage conditions such as time, temperature, pH, and bottle orientation.

To tackle the variability in OTR of natural cork stoppers, a new process has been introduced into production lines. This process uses advanced imaging and deep learning to analyze the internal structure of corks and correlate it with their OTR, effectively distinguishing corks with high OTR from the standard range. This allows for real-time sorting of corks during manufacturing, ensuring that only those with suitable OTR values are used, thereby enhancing the consistency and quality of wine by minimizing undesirable oxidation effects. This method has been validated through established OTR measurement techniques (UVAMOX, Spain).

Funding Support: Cork Supply Portugal, S.A

How Temperature and Nutrition Affect the Fermentation and Sensory Profile of Chardonnay

Coline Leriche, Anne Flesch,* Stéphanie Rollero, Arnaud Delaherche, Maryam Ehsani, Gabriela Montandon, and Etienne Dorignac
*Fermentis, 137 rue Gabriel Péri, 59700 Marcq-en-Baroeul, France (a.flesch@fermentis.lesaffre.com)

Fermentative microorganisms are affected by the physiochemical characteristics of their environment. In winemaking, temperature and yeast nutrition play a major role in wine quality and sensory profile. They affect aroma production during fermentation and temperature also influences fermentation duration, which can modulate aroma content. While many studies focus on temperature and nitrogen effects, few examine the combination between these factors, including the type and timing of nutrient addition.

We studied the simultaneous effect of three factors on fermentation kinetics, aroma production during fermentation, and sensory profile: i. temperature of fermentation (T), ii. yeast assimilable nitrogen (YAN), iii. type and moment of nutrient addition (N), in a Burgundy Chardonnay wine.

To do so, a Box-Behnken experimental design was used to determine 14 treatments to be studied, with a triplicate in the medium case. Studied temperatures were 12, 16, and 20°C, the ratio YAN/Sugar (mg N/g S) varied from 0.8, 1 to 1.2 in model N-deficient or excess musts, and nutrition was varied using organic or mineral N-rich nutrient, equally used at the pitching moment or at 30% fermentation. Fermentations took place in 20-L temperature-controlled vessels, on a Chardonnay must from Burgundy inoculated with 20 g/hL of yeast, and malolactic fermentation was blocked to avoid tasting bias.

Kinetics were monitored during fermentation and classical fermentative aromas were analyzed after verifying the implantation of the yeast in the must. Descriptive profile tasting was conducted by a panel of 10 well-trained professionals familiar with Chardonnay from Burgundy. This study presents a scientific exploration of fermentation management through temperature and nutrition regimes and illustrates the potential leverage of yeast to produce quality wines.

Funding Support: Fermentis, division of S.I. Lesaffre

Adam Gilmore | Jana Hildreth | Lyufei Chen

Classical Least Squares Assay of Wine Colorants with Absorbance-Transmittance Excitation Emission Matrix (A-TEEM) Data

Adam Gilmore,* Jana Hildreth, and Lyufei Chen
*Horiba Instruments Inc, 9 E View Ct, Flemington, NJ, 08822
(adam.gilmore@horiba.com)

Commercial additive concentrates (CAC) of Teinturier grapes with intensely colored skins and flesh, enriched in malvidin-3,5-diglucoside, are commonly used covertly to enhance color in finished wines from Vitis vinifera sp. grapes. The target CAC concentration is typically at least 0.2% by volume. This study investigates the detection of CAC with A-TEEM spectroscopy using a recently introduced, single-variable adjustment classical least squares (CLS) method known as Gray-CLS (Eigenvector Inc., Solo v9.3.1). The first-principles-based Gray CLS-results are compared to other multivariate regression methods, including partial least squares (PLSR), locally weighted regression (LWR), and extreme gradient boosting (XGBR). The experiment included several wines from different grape varieties spiked at varying concentrations with a commercially available CAC. A-TEEM measurements were collected under Beer-Lambert linear absorbance conditions at a constant temperature (20°C) using a standard solvent (50% EtOH, pH 2) and 0.45 micron filtration. The model data included both a calibration (cross validation set) of ~80% of the samples and an independent validation set comprising ~20%. The Gray-CLS model yielded a standard deviation (SD) of ~10% of the target CAC (0.2%) for the validation set by optimizing only the general least squares weighting variable of the CLS residuals. PLSR, XGBR, and LWR achieved similar or slightly lower SD values. However, these methods all required complex and potentially ambiguous optimization of multiple preprocessing variables of the spectral and concentration data blocks and other algorithm-tuning parameters, including the number of latent variables and/or principal components, among others. These methods, prone to under- or over-fitting, are thus potentially unreliable. We conclude the A-TEEM method can be an effective tool to quantify CAC using Gray-CLS to avoid issues with under- and over-fitting multivariate regression models, yielding results relevant to commercial wine quality evaluation.

Funding Support: Horiba Instruments Inc. Internal Funds

Ana Hranilovic | Enzo Barbier | Marion Favier | Joana Coulon

Enhancing Piquette Profiles with Lachancea thermotolerans

Ana Hranilovic,* Enzo Barbier, Marion Favier, and Joana Coulon
*Laffort, 11 Rue Aristide Berges, 33270, France (ana.hranilovic@laffort.com)

Piquette is a low-alcohol beverage made primarily from leftover winemaking pomace and water. With historical roots and a recent resurgence, it meets modern consumer demands for lighter, sustainable beverages. Piquette fermentations often rely on ambient microorganisms, potentially resulting in unpredictable profiles. In this study, we tested the lactic acid-producing yeast Lachancea thermotolerans (Zymaflore Omega) in piquette production to address issues of low acidity/high pH. Sauvignon blanc pomace was sourced from a winery in Bordeaux after routine processing of grapes. Equal amounts of pomace were distributed into fermenters, followed by the addition of three different volumes of water: equivalent to, double, and half the volume of the pomace mass. For each water addition, two fermentation regimes were compared: inoculation with Omega (200 ppm) and uninoculated treatments. After five days, the samples were pressed off skins and subjected to physicochemical and sensory profiling. The analytical profiles varied based on water addition and fermentation regime. All samples fermented to dryness, with ethanol levels ranging from 3.9 to 6.7% ABV depending on the dilution. Samples with the highest ethanol levels had the highest pH (4.0) regardless of the inoculation regime. The lowest pH (3.8) was observed in the modality fermented with Omega, following double water addition. Malic acid was not detected in any samples, indicating complete MLF. However, Omega-treated samples had higher lactic acid levels due to partial conversion of sugars into lactate by L. thermotolerans. Conversely, uninoculated samples contained more acetic acid. The polyphenolic profiles and color (CIELAB) also differed between the samples. Inoculation of Omega resulted in higher scores of aroma intensity, thiols, balance, freshness, body, and overall impression, regardless of the water addition level. Together, these findings highlight the potential of harnessing microbial diversity to create alternative beverages with enhanced profiles, aligning with the principles of circular economy.

Funding Support: Laffort

Ana Hranilovic | Enzo Barbier | Marion Favier | Joana Coulon

Enhancing Piquette Profiles with Lachancea thermotolerans

Ana Hranilovic,* Enzo Barbier, Marion Favier, and Joana Coulon
*Laffort, 11 Rue Aristide Berges, 33270, France (ana.hranilovic@laffort.com)

Piquette is a low-alcohol beverage made primarily from leftover winemaking pomace and water. With historical roots and a recent resurgence, it meets modern consumer demands for lighter, sustainable beverages. Piquette fermentations often rely on ambient microorganisms, potentially resulting in unpredictable profiles. In this study, we tested the lactic acid-producing yeast Lachancea thermotolerans (Zymaflore Omega) in piquette production to address issues of low acidity/high pH. Sauvignon blanc pomace was sourced from a winery in Bordeaux after routine processing of grapes. Equal amounts of pomace were distributed into fermenters, followed by the addition of three different volumes of water: equivalent to, double, and half the volume of the pomace mass. For each water addition, two fermentation regimes were compared: inoculation with Omega (200 ppm) and uninoculated treatments. After five days, the samples were pressed off skins and subjected to physicochemical and sensory profiling. The analytical profiles varied based on water addition and fermentation regime. All samples fermented to dryness, with ethanol levels ranging from 3.9 to 6.7% ABV depending on the dilution. Samples with the highest ethanol levels had the highest pH (4.0) regardless of the inoculation regime. The lowest pH (3.8) was observed in the modality fermented with Omega, following double water addition. Malic acid was not detected in any samples, indicating complete MLF. However, Omega-treated samples had higher lactic acid levels due to partial conversion of sugars into lactate by L. thermotolerans. Conversely, uninoculated samples contained more acetic acid. The polyphenolic profiles and color (CIELAB) also differed between the samples. Inoculation of Omega resulted in higher scores of aroma intensity, thiols, balance, freshness, body, and overall impression, regardless of the water addition level. Together, these findings highlight the potential of harnessing microbial diversity to create alternative beverages with enhanced profiles, aligning with the principles of circular economy.

Funding Support: Laffort

Bio-Acidification of Wines with the Yeast Lachancea thermotolerans

Ana Hranilovic,* Marina Bely, Isabelle Masneuf-Pomarede, Joana Coulon, Warren Albertin, and Vladimir Jiranek
*Laffort, 11 Rue Aristide Berges, France (ana.hranilovic@laffort.com)

Insufficient acidity in grapes is commonly corrected by adding tartaric acid during winemaking. An alternative approach involves bio-acidification with Lachancea thermotolerans (LT) via lactic acid production during fermentation. Our work first described the genetic and phenotypic diversity of ~200 LT strains, then tested the performance of their subset conjunction with Saccharomyces cerevisiae (SC). An LT strain with exceptional bio-acidifying properties was selected (Zymaflore Omega) and further characterized across a range of conditions. The follow-up study aimed to compare the profiles of bio-acidified LT wines and acid-adjusted SC wines, and to evaluate the use of LT wines as blending components. High sugar/pH Merlot was fermented with a sequential culture of LT and SC, and an SC monoculture. The aliquots of the SC control (4.0) were acidified with either tartaric or lactic acid to the pH of LT wine (3.6). The initial LT and SC wines were also blended in three proportions (1:3, 1:1, 3:1). Chemical analysis revealed major differences in various wine parameters (e.g., ethanol content, acidity, color, volatile compounds, amino acids). The compositional modulations were reflected in wine sensory profiles, confirmed via rate-all-that-apply evaluation by 30 wine experts. Sensory profiles of the bio-acidified LT wine and the lactic acid-adjusted SC wine were similar, contrasting with the tartaric acid-adjusted SC wine. Lactic acid-adjusted SC wine had enhanced red fruit flavor, with less hotness, bitterness, and body than the tartaric acid-adjusted wine. This was driven by differences in acidity perception, affected by titratable acidity (rather than pH) of wines. An inhibition of Brettanomyces bruxellensis was also observed in the bio-acidified LT wine and the lactic-acid adjusted SC wine. The profiles of blends were modulated depending on the proportion of the bio-acidified wine, highlighting the potential of this approach to adjust wine acidity and style.

Funding Support: Laffort

_{Marion Favier | Ana Hranilovic | Margaux Bernard | Maitena Muro | Philippe Marullo | Karine Gay | Chantal Mansour | Joana Coulon}

New Microbial Tools to Face Climate Change

Marion Favier, Ana Hranilovic, Margaux Bernard, Maitena Muro, Philippe Marullo, Karine Gay, Chantal Mansour, and Joana Coulon*
*Biolaffort, 11 Rue Aristide Bergès, 33270 Floirac, Floirac, France (joana.coulon@laffort.com)

During the past decades, drastic changes in grape must composition have occurred, leading to wines with higher ethanol content and lower acidity (Van Leeuwen et al. 2019). Both linked to climate change, these two features can be addressed concurrently using innovative techniques for microbial selection.

Many efforts focused on non-Saccharomyces yeast selection to lower the ethanol/sugars ratio during alcoholic fermentation. Lachancea thermotolerans is one of the most interesting species because it partially routes glucose and fructose to L-lactic acid, de facto lowering ethanol production during alcoholic fermentation while also acidifying the wines. Previous studies highlighted the importance of strain selection, as not all strains are alike (Hranilovic et al. 2018), leading to the selection of one strain, Zymaflore Omega. Further assays also showed that the enological environment and inoculation scenario drastically influence lactic acid production, as described here.

This strain must be associated with a Saccharomyces cerevisiae strain to complete alcoholic fermentation. Our latest selection program delivered a strain concentrating most genetic elements linked to malic acid preservation/production and lower ethanol/sugars yield, named Zymaflore Klima. The L-malic acid production of this strain depends on the initial malic acid content but can lead to 0.5 to 1 g/L produced in low-malic acid musts, while losing 0.2 to 0.3% vol ethanol.

Malolactic fermentation leads to decreases in acidity due to transformation of L-malic acid into L-lactic acid. However, this can be tempered using an Oenococcus oeni strain selected for low citric acid consumption, named Lactoenos Berry. Considering several assays, results show that titratable acidity can gain 0.5 g/L as tartaric equivalents compared to indigenous strains.

Together, these three carefully selected microorganisms lowered ethanol by 0.5% vol and increased TA by up to 2 g/L.

Funding Support: Biolaffort

Daniele Pizzinato | Simone Vincenzi | Elvis della Giustina | Robin Caillieaudeaux | Céline Sparrow

Sparkling Wines and Effervescence: Effect of Different Molecules on Foam Quality

Daniele Pizzinato, Simone Vincenzi, Elvis della Giustina, Robin Caillieaudeaux,* and Céline Sparrow
*SAS SOFRALAB, 79 av. A.A. Thévenet CS 11031, 51530 Magenta, France (rcaillieaudeaux@sofralab.com)

Foam is among the most important quality parameters we can assess in sparkling wines. The pleasure and sensations perceived when drinking a sparkling wine, its drinkability or aromatic bouquet, are closely linked to the wine’s effervescence and the quality of its bubbles. To understand what influences this, it is pertinent to begin by studying objective analytical parameters in base wines.

The aim of this work, carried out in collaboration with the Department of Oenology at the University of Padua, was to clarify the role of “amphipatic” molecules, compounds that play a positive, active role in foam quality. At the same time, other molecules such as bentonite were studied for their opposite effect.

The Mosalux instrument, designed by the Station Oenotechnique de Champagne (SOEC), was used to collect data on three qualitative parameters used to assess foam quality: HM (maximum height), HS (stability height), and TS (stability time). This method enabled us to compare the positive or negative effects of different molecules on the foam quality of sparkling wines, and therefore their overall quality.

Funding Support: Private company resources (SAS SOFRALAB)

Mike Faulk | Liliana Carreto | Lucia Bilro

WinePlus: The Revolutionary Remote and Real-Time Wine Fermentation Process Monitoring System

Mike Faulk,* Liliana Carreto, and Lucia Bilro
*Enartis USA, 7795 Bell Rd, Windsor, CA 95492, United States, Windsor, CA, 95492 (michael.faulk@enartis.com)

The wine industry is moving toward digitalization of traditional measuring techniques. Fermentation is the most important stage of winemaking, where the sugar is chemically transformed into alcohol. Constantly monitoring parameters and adjusting them via the addition of enological products, according to readings and determined nutrient requirements, is not only labor-intensive, time-consuming, and inefficient, but also has limited forecasting capabilities. This is a major issue, as the incidence of stuck and arrested fermentations may reach 20%. Tardy, reactive adjustments of the fermentation conditions result in wine losses of both quality and quantity. The high carbon dioxide and water losses have led to the wine industry having the third largest carbon footprint of any industry. These factors combined make more efficient, economically and environmentally sustainable solutions for monitoring fermentation desirable. This solution must be fully integrated and provide real-time values of parameters that are predictive during fermentation. Wineplus is a revolutionary, cost effective, scalable, IoT-based, integrated solution for real-time monitoring of fermentation, with forecasting and preventive capabilities, to achieve sustainable, cost-effective production of high-quality wine. It uses the principle of pressure sensing and advanced AI algorithms to measure density accurately. It also measures the liquid level for tracking operations and volume monitoring. By implementing this system, Wineplus has already improved the vinification process by reducing time consumption up to 73%, allowing for multi-cellar control. This solution has the potential to reduce by 20% the carbon and water footprint of vinification. Several case studies of tank and barrel fermentations will be presented.

Funding Support: WineGrid and Enartis

P1	Evaluation of Alternative Varieties in the Willamette Valley AVA using the Average Growing Season Temperature Index Bryan Berenguer, Chemeketa Community College, Oregon
P2	Assessing Long-Term Effects of Regenerative Management Practices on Vineyard Soil Health Lauren Picone, California Polytechnic University, San Luis Obispo Flash Talk: June 19, 2024, 4:30:00 pm
P3	Influence of Vineyard Planting on Soil Physical and Hydraulic Properties Devin Rippner, United States Department of Agriculture-Agricultural Research Service, Washington
P4	Using Passive Samplers to Measure Volatile Phenols in Smoke to Correlate to Concentrations in Grapes and Wines Arran Rumbaugh, United States Department of Agriculture-Agricultural Research Service, California
P5	Heard it Through the Grapevine: Assessing the Spatial Variability of Hydrometeorological Controls in Canadian Vineyards Jessica Williamson, University of Waterloo, Canada
P6	Sunscreen for Grapevines: Kaolin Clay Use in Pacific Northwest Vineyards Cody Copp, Oregon State University, Corvallis
P7	Smoke Volatile Phenol Diffusion Capabilities through Cellulose Nanofiber-Based Films Lindsay Garcia, Oregon State University, Corvallis
P8	HiRes Vineyard Nutrition Project Seeks to Develop New Tools and Refine Nutrient Thresholds Nataliya Shcherbatyuk, Washington State University, Prosser
P9	Impact of Grapevine Red Blotch Virus Infection on Grape Skin Cell Wall Composition over Two Growing Seasons Arpa Boghozian, University of California, Davis
P10	Exploring Berry Astringency in Table Grapes Ashraf El-kereamy, University of California, Riverside
P11	Could Foliar-Applied Prohexadione Calcium and Phenylalanine Affect the Phenolic Content of Marquette? Alexander Gapinski, Iowa State University, Ames
P12	Exploring Auxin Responsive Factor 4’s Influence on Timing of Ripening Initiation Using Molecular Breeding Rushil Patel, Oregon State University, Corvallis Flash Talk: June 19, 2024, 4:33:15 pm
P13	Identifying Protein-Protein Interactions in Red Blotch Infected Vines Abram Smith, Oregon State University, Corvallis Flash Talk: June 19, 2024, 4:36:30 pm
P14	A Two-Year study of 12 Sustained and Regulated Deficit Irrigation Schedules for Cabernet Sauvignon in Central California Vincenzo Cianciola, California State University Fresno Flash Talk: June 19, 2024, 4:39:45 pm
P15	Enhancing Water Use Efficiency and Berry Ripening in Cabernet Sauvignon: Effects of Irrigation Regimes and Biostimulants Alessandro De Rosa, California State University, Fresno Flash Talk: June 19, 2024, 4:43:00 pm
P16	A Comparative Study of Traditional Drip Irrigation and Deep Underground Irrigation to Improve Water Use Efficiency Desiree Hernandez, California State University Fresno Flash Talk: June 19, 2024, 4:46:15 pm
P17	Effect of Irrigation Initiation Time on Methoxypyrazine and C13-norisoprenoid Composition in Pinot noir Wine Tingting Ye, Oregon State University, Corvallis Flash Talk: June 19, 2024, 4:49:30 pm
P18	Toward Real-Time Selective Harvesting and Grape Composition Mapping by Integrating Hyperspectral Sensing into Harvesters Luca Brillante, California State University, Fresno
P19	Advancing Cold Hardiness Evaluation in Grapevine Mapping Populations Hava Delavar, North Dakota State University, Fargo
P20	Accelerating Molecular Breeding via Development of a Novel Multiplexed Gene-Editing Method for Vitis vinifera Kenneth Donsky, Oregon State University, Corvallis Flash Talk: June 19, 2024, 4:52:45 pm
P21	Spray-Induced Gene Silencing (SIGS) with Carbon Dots for Enhanced RNA Delivery in Grapevine Christian Mandelli, Oregon State University, Corvallis Flash Talk: June 19, 2024, 4:56:00 pm
P22	Simulating Natural Wildfire Smoke Events in a Vineyard: Challenges and Solutions Suraj Kar, Oregon State University, Central Point
P23	Development of a High-Throughput Phenotyping Method to Assess Boron Tolerance for Breeding Programs Yaniv Lupo, University of California, Davis
P24	Testing the Application of a Novel Technology for Assessing Grape Maturity Using Spectrometry Bronwyn Riddoch, University of Waterloo, Canada Flash Talk: June 19, 2024, 4:59:15 pm
P25	Initiation of a Three-Year Survey to Characterize the Distribution and Abundance of Nematodes in Oregon Vineyards Ricky Clark, Oregon State University, Central Point
P26	Mitigation of Grapevine Red Blotch Disease Effects using Potassium and Inducers of Plant Resistance Joseph DeShields, Oregon State University, Central Point
P27	Optimizing Biofungicide Use for Control of Grapevine Diseases on the Central Coast of California Edgar Godoy-Monterroso, California Polytechnic State University, San Luis Obispo Flash Talk: June 19, 2024, 5:02:30 pm
P28	Summer Bunch Rot and Sour Rot Management on Table Grapes in the San Joaquin Valley Joy Hollingsworth, University of California Cooperative Extension, Tulare and Kings County
P29	Understanding the Mechanistic Basis of the Red Blotch Virus Infection for Better Disease Management Bhaskar Bondada, Washington State University, Tri-Cities
P30	Advancing Vineyard Irrigation in the San Joaquin Valley, California, with Hyperspectral-Based Plant Water Status Mapping Eve Laroche-Pinel, California State University, Fresno
P31	Establishing Baseline Data for Carbon Isotope Discrimination as an Effective Indicator of Rootstock Drought Tolerance Suraj Kar, Oregon State University, Central Point
P32	Warmer but Longer Cold Air Exposure Can Hurt Ben-Min Chang, Agriculture & Agri-Food Canada
P33	Characterizing Root System Architecture Traits for Drought Tolerance in Grapevine Rootstocks Sam Dudley, University of California, Davis Flash Talk: June 19, 2024, 5:05:45 pm
P34	Evaluating Nitrogen, Potassium, and Magnesium Fertilization Effects on Vine Nutrient Status and Productivity in Western Oregon Santosh Kalauni, Oregon State University, Corvallis
P35	Enhancing Vine Resilience and Delaying Ripening: Novel Late-Season Practices for Grape Production in Central California Luis Ortiz, California State University, Fresno Flash Talk: June 19, 2024, 5:09:00 pm
P36	Applications of Foliar Nutrients and Plant Growth Regulators can Improve Berry Firmness and Color in Red Tablegrape Tian Tian, University of California Cooperative Extension, Kern County
P37	Identification of 2-methylisoborneol as an India Ink-Like Off-Flavor in Syrah (Vitis vinifera cv.) wine Kanako YANAGISAWA, Kirin Holdings Company, Japan
P38	Autonomous Identification of Grapevine Varieties in Sentinel 2 Satellite Imagery Diego Freire Bastidas, California State University, Fresno
P39	Comparison of Freeze-Killed versus Freeze-Dried Leaves for the Production of Frost Tainted Cabernet Sauvignon Wines Mitchell Davey, Washington State University, Tri-Cities Flash Talk: June 19, 2024, 4:30:00 pm
P40	Use of Reverse Osmosis, Immobilized β-glucosidase, and Adsorption as Remedy for Smoke-Affected Wine Charity Maosah, Washington State University, Tri-Cities Flash Talk: June 19, 2024, 4:33:15 pm
P41	Effect of Cold Storage and Partial Grape Drying on Acidity and Aroma Precursors of Cold-Climate Interspecific Hybrids Karine Pedneault, Université du Québec, Canada
P42	Using Cover Crop to Mitigate the Effects of Winery Wastewater Application on Soil, Grape, and Wine Quality Jedediah Fitzgerald, California State University, Fresno Flash Talk: June 19, 2024, 4:36:30 pm
P43	Evaluation of Ripe-Fruit-Like Aroma in Red Wines using an Automated Omission System Kanako Sasaki, Kirin Holdings Company, Japan
P44	Surface-Enhanced Raman Spectroscopy for Quick Smoke Exposure Assessment Alec Sobotka, Oregon State University, Corvallis
P45	Effect of Biofungicides on Grape Quality, Composition, Fermentation, and Sensory Characteristics of Wines from California Quinn Cahoon, California State University, Fresno Flash Talk: June 19, 2024, 4:39:45 pm
P46	Effect of Soil and Foliar Nitrogen Applications on Syrah Fruit and Wine Tannin Concentration and Composition Juliana Pazos, Washington State University, Tri-Cities Flash Talk: June 19, 2024, 4:43:00 pm
P47	Chemical and Redox Potential Profiles of Assyrtiko Wines from California Fermented with and without Solids Federico Casassa, California Polytechnic State University, San Luis Obispo
P48	Influence of Sodium and Calcium-based Bentonite Dosage Rates on Alcoholic Fermentation Kinetics in Chardonnay Wines Sydney Fritsch, California Polytechnic State University, San Luis Obispo Flash Talk: June 19, 2024, 4:46:15 pm
P49	Effects of Sulfur Nutrient Additions on Thiol Concentration in Pinot noir Olivia Jefferies, Oregon State University, Corvallis
P50	Characteristic Extraction of Phenol Compounds in Koshu (Vitis vinifera cv.) Wine during Maceration Daiki Kiyomichi, Kirin Holdings, Japan
P51	Exploring Dipeptides and Oligopeptides in Wine by UHPLC–HRMS Liang Chen, E. & J. Gallo Winery, California
P52	Sauvignon blanc Wine Protein Stability as Affected by pH Adjustment and Timing of Bentonite Addition Bin Tian, Lincoln University, New Zealand
P53	How Many Strains of Brettanomyces are there? Integrating Global and Local Data Sets for Comprehensive Population Genomics Bjarne Bartlett, Oregon State University, Corvallis
P54	Enzymatic Degradation of Undesirable Phenols in Wines Contaminated by Brettanomyces or Smoke Taint Mary Riley, University of California, Davis Flash Talk: June 19, 2024, 4:52:45 pm
P55	Using In-source LC-MS/MS Fragmentation to Fingerprint Tannin Structural Diversity and Protein Precipitation Yanxin Lin, The Pennsylvania State University, State College
P56	Effect of Yeast Strain Selection on the Concentration of Smoke-Derived Volatile Phenols and Thiophenols in Wine Megan Meharg, Washington State University, Tri-Cities Flash Talk: June 19, 2024, 4:49:30 pm
P57	Advancements in Rapid Smoke Taint Evaluation with Absorbance-Transmission and Fluorescence Excitation-Emission Matrix Brandt Bastow, University of California, Davis
P58	Determining the Spoilage Potential of Brettanomyces Strains Isolated from Oregon Vineyards and Cellars C. Michael Sonza, Oregon State University, Corvallis Flash Talk: June 19, 2024, 4:59:15 pm
P59	Impact of Yeast Assimilable Nitrogen and Sugar on Sequential Fermentation with Metschnikowia pulcherrima and Saccharomyces cerevisiae Jonathan Brumley, Washington State University, Pullman Flash Talk: June 19, 2024, 4:56:00 pm
P60	Dissolved Oxygen Removal in Wines by Membrane Contactor and Nitrogen Sparging Angelita Gambuti, University of Naples, Italy
P61	Characterization of Polyphenol Elongation Induced by Exogenous Acetaldehyde Ezekiel R. Warren, The Pennsylvania State University, State College
P62	Assessing Color and Phenolics of Wines Produced from Co-fermentation of Vitis rotundifolia and Vitis vinifera Grapes Amanda Fleming, University of Arkansas, Fayetteville
P63	Genome-Wide Association Study of Anthocyanins and Phenolics in a Cold Climate Winegrape (Vitis spp.) Population Rajasekharreddy Bhoomireddy, North Dakota State University, Fargo Flash Talk: June 19, 2024, 5:02:30 pm
P64	Correlating Volatile Phenol Concentrations in Cabernet Sauvignon Grapes to Unfavorable Sensory Characteristics in Wines Bainian Chen, University of California, Davis Flash Talk: June 19, 2024, 5:05:45 pm
P65	Sensory and Chemical Analysis of Cabernet Sauvignon Wines Made from Unripe, Ripe and Overripe Grapes Danielle Fox, Washington State University, Tri-Cities
P66	Calcium Tartrate: New Assessment Method and Management of Instability Florencia Cremades, Enartis, California
P67	Relevance of Nitrate Assimilation by Brettanomyces bruxellensis in Low-Nitrogen Environments Jacob Martin, Oregon State University, Corvallis
P68	Exploring the Synergistic Effects of Lactobacillus plantarum and Oenococcus oeni in Malolactic Fermentation David Spector, Chr. Hansen, Wisconsin
P69	Comparative Analysis of Glutathione Production by Commercial Non-Saccharomyces Yeast Strains in Wine Fermentation David Spector, Novonesis, Wisconsin
P70	Natural Cork Classification Based on Oxygen Transmission Rate António César S. Ferreira, Cork Supply, Portugal
P71	Tatumella ptyseos’ Role in Early Degradation of Malic Acid in Grape Juice Jeffrey Maccario, ETS Laboratories, California
P72	How Temperature and Nutrition Affect the Fermentation and Sensory Profile of Chardonnay Anne FLESCH, Fermentis, Franc
P73	Classical Least Squares Assay of Wine Colorants with Absorbance-Transmittance Excitation Emission Matrix (A-TEEM) Data Adam Gilmore, Horiba Instruments Inc, New Jersey
P74	Enhancing Piquette Profiles with Lachancea thermotolerans Ana Hranilovic, Laffort, France
P75	New Kids on the Block: Novel Yeast Strains for Fresher Wine Profiles Ana Hranilovic, Laffort, France
P76	Bio-Acidification of Wines with the Yeast Lachancea thermotolerans Ana Hranilovic, Laffort, France
P77	New Microbial Tools to Face Climate Change Ana Hranilovic, Laffort, France
P78	Sparkling Wines and Effervescence: Effect of Different Molecules on Foam Quality Daniele Pizzinato, SAS SOFRALAB, France
P79	WinePlus: The Revolutionary Remote and Real-Time Wine Fermentation Process Monitoring System Mike Faulk, Enartis, California

2024 Poster Sessions

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Poster Sessions 2024

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Leticia Chacón-Rodríguez

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