Background and goals The oxidative stability of white wine strongly influences its sensory quality and shelf life. Although bottle closures have been widely studied, bottleneck geometry is an important but still overlooked factor affecting wine composition and quality. Methods and key findings By combining bottle geometric measurements with chemical characterization after forced aging, this work presents a preliminary study on the effect of bottleneck heterogeneity (n = 200) on white wine oxidation. Dissolved oxygen, free and total sulfur dioxide (SO2), and volatile markers were quantified. Results demonstrated that bottleneck heterogeneity had significant effects on oxygen management and SO2 depletion. Free SO2 decreased by 50%, with significant variability among bottle types, suggesting bottleneck profile influences oxygen ingress and antioxidant consumption. Aldehyde and furan concentrations increased in all bottles, with hexanal, trans-2-hexenal, phenylacetaldehyde, and methional exceeding odor thresholds, thereby affecting wine sensory quality. Additionally, hierarchical cluster analysis revealed strong correlations between bottleneck profile indicators and aldehyde accumulation. Conclusions and significance This study demonstrates the effect of bottleneck geometry on oxygen management and SO2 depletion in wine. The evidence presented here indicates that bottleneck geometry is a key contributor to variability in wine aging and shelf life, suggesting that it is a critical and overlooked factor in wine oxidation, composition, and quality. Stricter manufacturing tolerances in wine bottle production that integrate bottleneck measurements into closure performance assessment should be implemented.
Background and goals The grape mealy bug, Pseudo coccus maritimus, is found in most grapegrowing regions across the United States, however, its spatial and temporal distribution in mid-Missouri vineyards is unknown. Because the insect transmits grapevine leafrollassociated viruses (GLRaVs), which are common in mid-Missouri vineyards, the objectives of this study were to evaluate the presence of P. maritimus in mid-Missouri vineyards over the course of three growing seasons, confirm species identity through DNA barcoding, and genetically test female mealybugs for the presence of Grapevine leafroll-associated virus 3 (GLRaV-3). Methods and key findings Sex pheromone traps captured varying levels of male grape mealybugs at all survey sites during two distinct periods of each growing season. Genetic testing verified that female mealybugs present on vines were P. maritimus and that 10 out of 54 female mealybugs collected from test vineyards possessed GLRaV-3. Conclusions and significance These data confirm P. maritimus is widespread in mid-Missouri vineyards, that it produces two distinct reproductive cycles each season, and that it ingests GLRaV-3 from infected grapevines. Because the insect has previously been shown to be capable of transmitting GLRaVs to grapevines, it may be contributing to the high incidence rates of grapevine leafroll disease in the region.
Background and goals Accurate, fast, and cost-effective methods to assess smoke taint severity are essential for wineries to make processing decisions. Levels of volatile phenols related smoke taint may increase during winemaking via limited cleavage of conjugated precursors, though phenolic glycosides have been demonstrated to be stable during bottle aging. Release of nonvolatile precursors can occur during consumption via in-mouth enzymatic hydrolysis. Estimating the potential of smoke taint in wine requires measurement in grapes either by directly analyzing these precursors or by converting them into free forms through hydrolysis other methods. Small-scale fermentations are also used to evaluate potential off-aromas postfermentation. This study assessed three sample-preparation methods for the release of volatile aroma compounds related to smoke taint. Methods and key findings Microvinification was compared to acid hydrolysis and enzymatic hydrolysis in an evaluation of smoke taint risk by gas chromatography-tandem mass spectrometry (GC-MS/MS). Microvinification and enzymatic hydrolysis produced similar concentrations of volatile phenols. In contrast, acid hydrolysis released higher concentrations of free volatile phenols but showed greater variability and limited predictive accuracy. Conclusions and significance Microvinification closely mimics real winemaking conditions by incorporating yeast activity, alcohol extraction, and maceration, making it a realistic predictor of smoke taint severity. It also provides wineries with an in-house option for sample preparation before sending samples to external labs for volatile analysis, which may help minimize losses related to smoke taint.
Background and goals Peer knowledge networking groups connect growers, facilitate knowledge dissemination, and promote cooperation. Our goals were to document the structure, function, and impacts of such groups in California. Methods and key findings We interviewed the coordinators of eight groups and surveyed their members. Qualitative analysis of the interviews identified challenges of operating these groups, strategies to overcome them, and positive impacts. Challenges were recruitment, membership, leadership, and group processes. Positive impacts were increased knowledge sharing, social connections, practice adoption, pressure for regulatory change, future resilience, and reduced pest and disease pressure. Member survey data found that members established relationships, participated in group projects, adopted practices, and worked with their neighbors to coordinate practices and share expertise, data, and resources. A social network analysis of 249 individuals communicating about vineyard pest and disease management in Napa County illustrated such groups' central importance. Members scored higher on centrality measures compared to non-members, indicating that they communicate with more network actors and are more important intermediaries for information exchange. This difference was significantly magnified for members who joined multiple groups and transcended differences based on job role. Conclusions and significance In this work, we illustrate the positive impacts of the groups we studied, describing their capacity to establish a network of participants, provide a forum for continued engagement among members, and support the resilience of regional agricultural operations. Practical strategies for establishing and coordinating peer knowledge networking groups, as well as insights relevant to future efforts for expanding agricultural networks and harnessing their potential to engage growers in collective responses, are also suggested.
Background and goals Winegrape growers are expected to continue to face significant risks due to extreme weather events in many regions. The objective of this research was to develop a framework for evaluating the economic impacts of different strategies to manage risks associated with extreme heat in winegrape production. Methods and key findings We developed a financial model to calculate the net present value of the flow of revenues and costs for establishing and producing winegrapes in California for selected risk management strategies. A survey was used to assess consumers' willingness to accept wines that are produced in accordance with each management strategy. Overall, we found that in the presence of extreme heat events, economic returns to winegrape growers can improve with the selection of heat-tolerant cultivars and with the adoption of technologies designed to protect grapes from the sun. Conclusion and significance Our research outlines the economic consequences of climate change adaptation strategies and sheds new light on the relative merits of different approaches. We also offer a framework that wine-grape growers can use to evaluate a wide range of potential outcomes across new technologies, cultivars, and regions.
Background and goals Hot, dry conditions can exacerbate late-season berry dehydration, reducing yield and wine quality. Late-season dehydration occurs as mesocarp cells die, releasing water that is lost to berry transpiration or backflow to the canopy. We tested whether short pulses of increased irrigation could reduce late-season berry dehydration by interrupting stress-induced signals for cell death. Methods and key findings Conventional irrigation was compared with an early-and a late-pulse treatment, where irrigation was increased by-40% in the 2 wk immediately before or after the expected onset of cell death (-90 days after anthesis). We imposed each treatment on five vines of Cabernet Sauvignon growing in an experimental vineyard in Davis, California in an atypically hot (2022) and cool (2023) growing season. We monitored vine water potentials, berry cell death and shrivel index, and concentrations of putative signals for cell death (i.e., hydrogen peroxide [H2O2]) and markers of cellular damage. The late-pulse treatment significantly reduced the rate of cell death and the magnitude of berry shrivel at harvest, but only in the hot season (p < 0.05). Conversely, the early-pulse treatment did not affect the rate or timing of onset for cell death or shrivel (p > 0.05). H(2)O(2 )levels increased with cell death but were not affected by irrigation, indicating that other mechanisms produced the treatment effects on cell death. Conclusions and significance These findings suggest the onset of cell death is robust to irrigation, but a short pulse of supplemental irrigation soon after onset can slow the rate of cell death and mitigate late-season berry dehydration under hot growing conditions.
Background and goals Vineyard nutrient budgeting as a basis for efficient nutrient management is essential to maintain grapevine productivity and fruit quality. This study quantified nutrient removal through harvested fruit, senescent leaves, and pruned canes across four wine and juice grape cultivars in arid eastern Washington over 3 yr. Methods and key findings Vine tissue samples were collected from Chardonnay, Sauvignon blanc, Syrah, and Concord vineyards from 2021 through 2023. Biomass and concentrations of macro-and micronutrients were measured in harvested fruit, abscised leaves and, in wineg rapes, pruned canes. Overall, potassium and nitrogen accounted for the largest macronutrient losses. Fruit harvest was responsible for most of the nutrient removal, which varied with crop yield. Abscised leaves and pruned canes contributed additional potential nutrient losses, with higher biomass production amplifying the removal of macronutrients such as nitrogen and calcium. Early fall frost events disrupted the remobilization of foliar nutrients, especially nitrogen and phosphorus, leading to increased nutrient retention in senescent leaves. Conclusions and significance This study highlights the importance of properly accounting for annual nutrient losses in vineyards. The findings underscore the need for holistic nutrient budgets that incorporate all loss pathways to support long-term vineyard sustainability, providing actionable insights for optimizing fertilization strategies and improving nutrient use efficiency.
Grapevine rootstocks play an essential role in shaping the performance and sustainability of viticulture by influencing key traits such as disease resistance, vine vigor, yield, and fruit quality attributes, including sugar content and organic acid composition (Chen et al. 2024). As a result, selecting an appropriate rootstock has become a cornerstone of modern viticultural practices. Rootstocks affect grapevine physiology by modulating nutrient uptake, water-use efficiency, and photosynthetic performance, all of which contribute to enhancements in scion vigor and yield. For instance, improvements in nitrogen uptake capacity (Keller et al. 2001a, 2001b, Cochetel et al. 2017), water-use efficiency (Pou et al. 2022, Bernardo et al. 2025), and photosynthetic capacity (Soar et al. 2006) have been associated with rootstock selection, demonstrating their influence on grapevine performance. A growing body of research has evaluated the effect of rootstock on scion vigor, yield, and fruit quality traits (Walker et al. 2007, Kviklys et al. 2012, Kodur et al. 2013, Tecchio et al. 2022). However, the interaction between rootstock and scion often exhibits phenotypic variability such as higher yield accompanied by reduced sugar content, which complicates generalized evaluations of rootstock performance. In response to this challenge, efforts have been made to more systematically quantify rootstock contributions; for example, an index based on nitrogen uptake capacity has been proposed (Kulmann et al. 2020). While such indices provide a valuable starting point, they focus on isolated performance traits, emphasizing the need for more comprehensive frameworks that capture the multifactorial nature of rootstock performance. Environmental factors, including annual climatic variability and scion genotype, further compound the complexity of evaluating rootstock efficacy. It has been demonstrated that environmental conditions can exert effects on vine vigor, yield, and fruit quality that are 1.9 to 6.3 times greater than the influence of rootstock (Migicovsky et al. 2021), highlighting the critical importance of conducting long-term studies to ensure reliable and transferable insights. This variability underscores the necessity of adopting performance indices that can integrate multiyear data and account for environmental heterogeneity. To address these gaps, this study introduces two novel indices, the Rootstock Efficiency Index (REI) and the Rootstock Stabil-ity Index (RSI), designed to provide a holistic and accessible approach to evaluating grapevine rootstock performance. These indices synthesize data on scion vigor, yield, and fruit quality, offering a comprehensive yet practical means to assess rootstock performance under diverse environmental conditions. To validate their applicability, this study used a 16-yr data set collected in the Piedmont region of Italy, focusing on Muscat & agrave; petits grains blancs, a commercially significant scion variety that was grafted onto 10 rootstocks. As the trial was conducted in Italy, where the variety is locally known as Moscato bianco, this designation is used hereafter for consistency. Moscato bianco is used widely in sparkling wine production and is valued for its naturally high acidity and low pH, qualities that contribute to freshness in sparkling wines (Kerslake et al. 2014). Measured traits included yield components, pruning weight, vine balance (yield-to-pruning weight ratio), fruit quality metrics, and disease incidence, thereby capturing a wide array of factors that influence vine performance. By leveraging this long-term data set, the proposed indices can bridge the gap between trait-specific assessments and comprehensive performance evaluations. This approach not only provides a robust framework for rootstock selection, it also facilitates development of rootstocks tailored to meet the challenges of climate variability and evolving viticultural demands.
Background and goals Regardless of location, United States grape and wine industry stakeholders can experience similar challenges; however, distinct needs arise due to diverse climates and production systems employed. This work sought to quantify industry needs and challenges to better develop research, extension, and educational programming on national and regional levels. Methods and key findings A team of specialists from land grant universities across the U.S. assessed winegrape industry challenges and needs in three areas: viticulture, enology, and wine business and marketing. Information was gathered through an online survey distributed to grape and wine industry stakeholders across the nation. This was followed by regional focus group meetings to gather more detailed data based on survey results and to add context to industry concerns. Common themes emerged across the U.S. regions for viticulture, enology, and wine business and marketing. Pest and disease management were the main viticulture challenges. Enology challenges included acidity and microbial spoilage management. Wine business and marketing concerns focused on evolving consumer preferences. Conclusions and significance All focus groups noted the need for more targeted research and extension programs to address these primary challenges and local concerns. These findings may be used by others to develop vineyard production resiliency, winemaking techniques necessary to increase wine quality, and business and marketing strategies to reach more consumers.
Background and goals The water balance of a grape berry determines its final size and has implications for yield and quality. However, how water moves into and out of a berry and how water movement is affected by grapevine water status remains controversial. This synopsis examines the available evidence to develop suggestions for vineyard irrigation management. Methods and key findings Studies published over the past 20 yr have firmly refuted the notion that ripening grape berries become hydraulically isolated from the vine. Instead, the berries' high demand for sugar leads to a massive increase in phloem inflow that requires discharge of surplus water via berry transpiration and xylem backflow to the leaves. Although berry size becomes unresponsive to shortterm changes in soil moisture, ripening berries will shrink gradually when vines are water-stressed. Conversely, the berries' propensity to absorb surface water can result in berry splitting, leading to berry expansion or shrinkage, and thus dilution or concentration of berry contents, depending on weather conditions. Conclusions and significance Unlike rainfall, irrigation during grape ripening does not dilute grape composition-unless it is supplied by overhead sprinklers. This Insight argues that while some water deficit is desirable for high-quality grape production, growers should focus mostly on preveraison water deficit for maximum benefits.
Background and goals The manipulation of supplemental light and environmental conditions in greenhouses has been shown to increase grapevine size and fruiting capacity prior to transplanting and presents an opportunity for advanced starter plant material. The goal of this study was to conduct an economic analysis on Precise Indoor Vine Conditioning (PIVC) as a proof-of-concept system to optimize nursery production of grapevines. Methods and key findings Research costs from a PIVC study were organized into a crop budget. Using net present value (NPV) and data from existing commercial crop budgets, we modeled the grower profitability of establishing a new vineyard with PIVC vines in three grape production systems in the United States. In addition, we calculated the price premium for a PIVC vine beyond the cost of a conventional starter vine and used sensitivity analysis (with research costs as an input) to identify the most promising avenues for increasing profitability of PIVC vine production for a nursery. NPV analysis revealed that variety and region have a strong impact on production system profitability and the use of PIVC vines can be more profitable than conventional systems for Cabernet Sauvignon in the San Joaquin and Napa Valleys, CA. The price premium a grower may be willing to pay for a PIVC vine beyond the cost of a conventional vine was $0.52 to $7.43 for Cabernet Sauvignon in the San Joaquin Valley and $6.92 to $31.18 in the Napa Valley. Conclusions and significance PIVC vines have the potential to reduce costs and increase returns for growers during the early years of vine establishment, thereby increasing profit. The PIVC system can also be profitable for grapevine nurseries with reductions in production costs that come at commercial scale and increased vine density.
Background and goals The transition to regenerative agriculture (RA) is gaining attention for its potential to enhance sustainability in viticulture, but questions remain about its economic feasibility. This study investigates the farm-level economic implications of transitioning to RA in the viticulture sector, with an application to California's North Coast region, specifically Sonoma County. Methods and key finding s We analyzed data from four vineyards to evaluate the financial outcomes of implementing RA practices (e.g., no-till, composting, and livestock integration) compared to conventional viticulture (CV) practices. Our findings reveal that CV and RA practices result in comparable profitability over a 30-yr time horizon, with RA averaging 5% lower in net present value across vineyards, assuming no change in yields. While in-house RA practices involve higher initial costs, they provide long-term benefits, including lower operational expenses, improved soil health, and additional revenue from sheep grazing integration. The profitability of RA is influenced by site-specific factors such as grape variety, vineyard layout, vine age, and density, as well as by the ability to maintain yields or obtain price premiums that compensate for potential yield reductions. Conclusions and significance The results of this study suggest that RA practices can achieve economic outcomes comparable to CV practices over the long term, particularly under the site-specific conditions of Sonoma County. Understanding the financial tradeoffs and benefits of RA can support growers in making informed decisions about transitioning to more sustainable viticulture practices.
Background and goals Pseudococcus maritimus is the primary vector of grapevine leafroll-associated viruses (GLRaVs) in Washington State vineyards and can infest grape clusters. Neonicotinoids are used widely against Ps. maritimus, but resistance potential highlights the need for integrated pest management (IPM). Additional IPM strategies are needed to improve Ps. maritimus control, slow insecticide resistance, and mitigate GLRaV spread. Methods and key findings From 2021 to 2023, we deployed Pacific Biocontrol twist-tie pheromone dispensers on grapevines at 0, 25, 74, 148, and 247 dispensers per ha, and Tr & eacute;c & eacute; CIDETRAK GMB MESO dispensers at 0, 79, and 124 dispensers per ha. Male mealybug densities were monitored with Tr & eacute;c & eacute; Ps. maritimus lures in traps from May to October 2021 and from April to October 2022 and 2023. In all 3 yr, Ps. maritimus had two distinct flight periods but the timing and abundance of captured male mealybugs varied. Pheromone dispensers reduced peak trap captures, but no clear relationship was found between dispenser rate and Ps. maritimus capture. Conclusions and significance This study demonstrates that mating disruption has potential applications in an IPM program for Ps. maritimus. The timing of the two annual male flights indicates a single application of a passive dispenser lasting 4 to 5 mo, or a shorter-lived sprayable formulation could cover the seasonal period. A late-April pheromone dispenser deployment is recommended for Washington State. However, monitoring is encouraged to verify application timing on an interannual basis. The dispenser deployment rate requires further assessment as there was no significant difference (p > 0.05) between the lower and higher deployment rates for male Ps. maritimus captures in sentinel traps.
Background and goals Warming trends observed globally have fostered research to understand the effects of increasing temperatures on the yield and fruit composition of winegrapes. However, the impact of extreme heat events at the commercial scale remains unsubstantiated. The present study represents the first attempt to combine available long-term spatiotemporal climate data with historical yield and quality metrics to investigate the impact of heatwaves (two or more days with maximum temperature >= 38 degrees C) on commercial winegrape production. Methods and key findings Historical weather data (1981 to 2023) for five sites in California were modeled using clustering analysis, separating three clusters: cool seasons, seasons with preveraison heat, and seasons with postveraison heat. Actual or temperature-based phenological stages were used to discriminate heatwave timing. Historical records of fruit composition, yield, and harvest date were then analyzed to determine differences between years experiencing extreme heat events and cool seasons. Yield and harvest date were affected by the intensity and distribution of heat in the growing season. Preveraison heat led to an advancement of harvest and substantial yield losses-on average, 13 days and-30%, respectively. Postveraison heat resulted in lower yield losses (-22%) and even earlier harvest dates (-17 days). Fruit quality parameters most affected by heatwaves were sugar, malic acid, pH, color, and phenolic compounds. Early-versus late-season heat resulted in unique effects on individual quality markers. Conclusions and significance By linking climate observations with grape yield and quality metrics at harvest, this study provides measured effects of heatwaves for the grapegrowing industry at a regional scale and points to the need for specific mitigation strategies.
Background and goals Cold hardiness in dormant grapevine buds depends on water dynamics during winter. Understanding winter bud responses and their effects on summer leaf physiology is critical for developing cultivars adapted to harsh winters, while maintaining productivity. Semi-automated differential thermal analysis (DTA) is widely used to determine cold hardiness. In this study, we evaluated DTA alongside high-throughput sensor technologies (including hyperspectral and multispectral sensing) to assess their potential for cold-hardiness evaluation. The objective was to explore visible and infrared hyperspectral sensing as proxy traits to assess bud and leaf water content in grapevine. Methods and key findings Over three years, bud cold hardiness (measured for two years, 2023 and 2024) and summer physiology (data collected in 2024 and 2025) were evaluated across 86 F1 progenies from a cross between Vitis hybrid NY84.0101.03 and Vitis amurensis PI 588634. Bud absorbance analysis identified consistent predictive bands at 1874, 1875, and 1888 nm across varying winter severities. Summer leaf reflectance at 1868 and 1873 nm showed strong correlations with winter bud hardiness. Among physiological traits, all but preveraison leaf-to-air vapor pressure deficit and chlorophyll fluorescence at veraison correlated positively with cluster and berry size. Stomatal conductance emerged as a key trait, showing both positive and negative associations with DTA values, depending on winter severity in 2023 and 2024. Conclusions and significance Bud absorbance, which is related to water content, can serve as a reliable proxy for bud cold hardiness, traditionally measured by DTA. In contrast, hyperspectral measurement of the anthocyanin reflectance index in leaf tissues may be used as a selection trait during summer. Twelve progenies were identified as stable performers, offering valuable material for pre-breeding efforts to combine cold tolerance with vine productivity.
Background and goals Pesticide drift and its potential for human and environmental exposure are of significant concern during vineyard airblast spray applications. This study aimed to quantify drift from grape vineyard pesticide applications for the purpose of validating an ongoing drift mechanistic model development. Methods and key findings A field study was conducted in a commercial Vintage Red table grape vineyard in Del Rey, California. The spray application of a fluorescent tracer dye solution was completed in 20 test runs, with the sprayer making four passes along the third drive lane upwind from the edge of the vineyard. Using a flat plastic card, artificial foliage, and horizontal and vertical polyester string samplers, airborne dye drift and drift deposition were captured, analyzed by fluorometry, and expressed as percentage of the applied rate. Meteorological data during the experiment were recorded inside and outside the vineyard using two meteorological stations with sensors installed at various heights. Airborne drift value significantly reduced (p < 0.05) from a downwind distance of similar to 8 to similar to 23 m, where it was measured. For all samplers, drift deposit also generally declined progressively, with downwind distance up to similar to 165 m under the different meteorological conditions that prevailed. Conclusions and significance The results and data provide a more complete understanding of potential downwind pesticide exposure caused by drift, which will be utilized in confirming and/or developing new best practices for spray application to promote efficiency, effectiveness, and environmental sustainability.
Background and goals This study investigated the bacterial diversity of Traminette, an important hybrid grape used for winemaking in the midwestern and eastern United States. The role of wild fructophilic lactic acid bacteria (FLAB) in the formation of lactic acid and mannitol during fructose metabolism, as well as its possible role in malolactic fermentation, was also determined. Methods and key findings High-throughput DNA metabarcoding sequencing of DNA extracted from samples at various stages of wine production identified an abundance of the operational taxonomic unit that includes genera such as Faecalibacterium, Peptoclostridium, Lactiplantibacillus, Roseburia, Bacillus, and Veillonella. It also identified Clostridium, Listeria, and Enterococcus, genera which may be of safety concern in wine. Across the different wine production stages, beta diversity and differential abundance indicated that yeast nutrients play a role in bacteria dynamics. In addition, Venn analysis of the relative abundance indicated that 53 common unique genera were shared in the Traminette R fermentation tank, and 45 genera were shared in the Traminette L fermentation tank. Cultured FLAB strains identified using sequencing of the almost-complete 16S rRNA gene included Leuconostoc citreum, Lactococcus lactis subsp. hordniae, and Lactiplantibacillus plantarum. Although fructophilic Lp. plantarum F4 demonstrated fructose metabolism similar to that of the reference strains of Lp. plantarum and the Fructobacillus fructosus FB3a strains, randomly amplified polymorphic DNA gel fingerprints revealed differences in the genomes of the strains. Lp. plantarum F4 did not express the mannitol dehydrogenase gene but did express the mle gene which is responsible for the decarboxylation of malic acid in artificial wine medium. High-performance liquid chromatography indicated no residual fructose or l-malic acid in artificial wine medium at pH 3.8 and 12% ethanol when used for fermentation. Conclusions and significance This study identified the abundance of Bacillota genera during Traminette grape fermentation and suggests the use of fructophilic Lp. plantarum F4 during secondary fermentation of wine to reduce residual fructose and convert l-malic acid to l-lactic acid. These results indicated the diversity of bacteria associated with Traminette grape and the possible ecological applications during wine production.
