Understanding the processes that shape microbial community structure is a central challenge in ecology. The relative importance of deterministic and stochastic processes in driving the microbiome assembly and composition remains poorly understood across diverse animal and plant hosts. Here, we characterized the bacterial (16 S rRNA) and fungal (ITS rRNA) communities in invasive pest spotted wing Drosophila (SWD, Drosophila suzukii) and sour-rot-affected grapes from seven California vineyards using high-throughput sequencing. We found that while the bacterial microbiome of male and female SWD was compositionally similar, these communities were entirely distinct from those on sour rot-affected grapes, indicating strong host-specific filtering. SWD also harbored substantially higher microbial density and greater diversity compared to grapes. Ecological modeling revealed a fundamental divergence in assembly mechanisms: SWD communities were predominantly shaped by stochastic processes, with a neutral model explaining 40

A nematode survey was conducted from 30 vineyards in Missouri and Arkansas (USA) comprising 107 samples among 21 grape cultivars (Vitis aestivalis, Vitis labruscana, Vitis vinifera, Vitis hybrids, and Muscadinia rotundifolia). All the samples tested positive for nematode presence. Eleven different nematode taxa were isolated and identified, five of which have economic importance to grapevines: Xiphinema americanum, Meloidogyne spp., Pratylenchus spp., Criconemoides spp., and Tylenchulus spp. Xiphinema americanum was detected at all but two sites, with 58% of sites having populations at or above levels with expected biological and economic impact. This is primarily a concern because of the ability of X. americanum to transmit Tomato ringspot virus and other viruses. The other four nematode taxa of concern were present in fewer samples and at much lower population densities. Xiphinema index, known to vector Grapevine fanleaf virus was not identified in any of the samples collected.

Annual rings from 30 year old vines in a California rootstock trial were measured to determine the effects of 15 different rootstocks on Chardonnay and Cabernet Sauvignon scions. Viticultural traits measuring vegetative growth, yield, berry quality, and nutrient uptake were collected at the beginning (1995 to 1999) and end (2017 to 2020) of the lifetime of a vineyard initially planted in 1991 and removed in 2021. X-ray Computed Tomography (CT) was used to measure ring widths in 103 vines. Ring width was modeled as a function of ring number using a negative exponential model. Early and late wood ring widths, cambium width, and scion trunk radius were correlated with 27 traits. Modeling of annual ring width shows that scions alter the width of the first rings but that rootstocks alter the decay of later rings, consistently shortening ring width throughout the lifetime of the vine. Ravaz index, juice pH, photosynthetic assimilation and transpiration rates, and instantaneous water use efficiency are correlated with scion trunk radius. Ultimately, our research indicates that rootstocks modulate secondary growth over years, altering physiology and agronomic traits. Rootstocks act in similar but distinct ways from climate to modulate ring width, which borrowing techniques from dendrochronology, can be used to monitor both genetic and environmental effects in woody perennial crop species.

In the midwestern United States, especially Missouri, winegrape (Vitis sp.) growers mostly plant interspecific hybrids, which are well adapted to the climate and pests of the region. ‘Chambourcin’ (an interspecific French-American hybrid) is one of the most widely planted winegrape cultivars in the area. It is usually grown as own-rooted (nongrafted) vines because the economic and horticultural benefits of grafting this cultivar to rootstocks have not been well developed. Further, few significant winegrape rootstock evaluations have been conducted in the midwestern United States, including evaluations of newer rootstocks developed and released by private and public breeding programs. The aim of this study was to assess the potential value of using rootstocks in ‘Chambourcin’ production in southern Missouri, with implications for the midwestern United States. Fruit yield, vine growth, and fruit composition metrics from ‘Chambourcin’ on 10 different root systems [own-rooted, and grafted to rootstocks ‘Couderc 3309’, ‘Couderc 1616’, ‘Paulsen 1103’, ‘Sélection Oppenheim 4’, ‘Millardet et de Grasset 420A’, ‘Millardet et de Grasset 101-14’, ‘Kingfisher’, ‘Matador’ (all Vitis sp.), and ‘Gloire de Montpellier’ riverbank grape (Vitis riparia)] in an experimental vineyard in southwest Missouri were compared. Following three establishment years (2008–10), data were collected across four growing and vintage seasons (2011–14). Yield components evaluated included total fruit production, clusters per vine, cluster weight, berry weight, weight of cane prunings, and crop load. Petiole mineral analysis was conducted in 2011, 2013, and 2014. Grape juice attributes measured were soluble solids concentration, juice pH, titratable acidity (TA), potassium (K), anthocyanins, tannins, phenolics, and organic acids. When simply comparing grafted vs. ungrafted vines, grafting generally induced higher plant vigor and a higher pH in the juice, whereas the other parameters did not differ. When the performances were compared among the 10 root systems, vines grafted to ‘Couderc 3309’ had higher yields compared with vines grafted to six other rootstocks and own-rooted vines. Grafting to ‘Millardet et de Grasset 101-14’ induced higher cluster weight compared with the other rootstocks. The ‘Millardet et de Grasset 420A’ rootstock promoted a higher pH and TA as well as a higher concentration of K in the juice, and ‘Paulsen 1103’ also promoted high pH, TA, and malic acid in the juice, and higher concentrations of phosphorous (P) and K in the petiole compared with most rootstocks. ‘Gloire de Montpellier’ induced a lower P content in the petiole and a higher tartaric/malic acid ratio. Rootstock use can strongly influence some vineyard production metrics as well as nutrient uptake and K levels in the juice (the latter further influencing juice pH). The results of this study provide insights into the complex viticultural and enological interactions resulting from the use of rootstocks in hybrid winegrape production in Missouri, USA.

One of the most popular winegrapes (Vitis sp.) for red wine production in the midwestern United States is ‘Chambourcin’, a French-American hybrid. It is typically produced on own-rooted vines in the region, but the potential benefits of grafting it to improved rootstocks are becoming better-known. Nematodes present occasional serious winegrape production challenges in the midwestern United States, and are capable of transmitting pathogenic viruses. New rootstocks developed by University of California, Davis (UCD GRN series) are resistant to several species and races of nematodes, but have not been evaluated under midwestern U.S. production conditions. A study with ‘Chambourcin’ grafted to four of these new nematode-resistant rootstocks (‘UCD GRN-2’, ‘UCD GRN-3’, ‘UCD GRN-4’, and ‘UCD GRN-5’) and ‘Couderc 3309’, along with own-rooted vines was established in 2010 in southwest Missouri, and fruited in 2013–15. Three of the nematode-resistant rootstocks (GRN-2, 3, 4) performed as well as the standard ‘Couderc 3309’ and own-rooted vines, with yields among all rootstocks ranging from 10 to 13 kg/vine. The rootstock ‘UCD GRN-5’ generally performed poorly, however, manifested by low pruning weights and a high Ravaz index value (25) in 2013 that necessitated defruiting the vines in 2014. Fruit yields on ‘UCD GRN-5’ rootstocks were satisfactory in 2013 and 2015, but the vines eventually deteriorated, with 99% shootless nodes by 2017. Although more evaluations of these new rootstocks are needed in the midwestern United States, we conclude that ‘UCD GRN-2’, ‘UCD GRN-3’, and ‘UCD GRN-4’ show promise, whereas ‘UCD GRN-5’ does not appear suitable for growing conditions in southern Missouri.

An evaluation of establishment techniques and rootstocks for ‘Chambourcin’ hybrid grape (Vitis sp.) was conducted 2009–12. Our objective was to evaluate four establishment methods and their interactions with grafted and ungrafted vines in terms of vine morphology and early fruit production under southwest Missouri conditions. The study was established in May 2009, as a factorial experiment comparing four establishment methods (open-trained without protection—two shoots, grow tube protected—two shoots, paperboard carton protected—two shoots, and fan-trained without protection—six shoots) across two vine types (own-rooted and grafted to ‘Couderc 3309’ hybrid grape rootstock). All vines in four of 12 field replicationswere destructively harvested near the conclusion of the first growing season, with leaf area and total vine dry matter determined. In years 3 and 4, yield, fruit composition, and vegetative growth were determined from the eight remaining replications. The fan training method increased leaf area and total vine dry matter compared with the other methods, but none of the establishment techniques affected fruit yield. Trunks that were tube protected had longer internodes, smaller diameter, and less dry matter, whereas both protection devices reduced glyphosate injury. Vine type (grafted and ungrafted) did not impact total leaf area or dry weight during the establishment year, but grafted vines had increased trunk and root shank dry weights compared with own-rooted vines. Grafted vines produced greater fruit yield in 2012. The fan training method required more labor to execute; although it was successful at increasing leaf area and root dry weight, it increased susceptibility to glyphosate injury and did not promote increased precocity or early fruit yield.

Impact of canopy management practices were assessed on canopy architecture, yield, and fruit composition of Norton grapes. Combinations of shoot thinning (ST), shoot positioning (SP), and leaf removal (LR) were imposed. The highest total soluble solids and lowest acidity were recorded either in LR or its combination with ST+SP treatments. Malic acid and potassium concentrations were highest on control, ST, SP, ST+SP vines. Canopy characteristics measured by point quadrat analysis differed significantly between treatments with more leaf layer number and less percent gap in control vines and in vines without LR treatments. These same treatments also recorded highest percent interior leaves and clusters.

# Exploration of Savory Wine Aroma via Descriptive Analysis and Gas Chromatography–Olfactometry {#article-title-2} The practice of extended bottle aging to increase wine quality is traditionally carried out by wine producers and négociants as well as wine collectors. Mainly red wines are

The influence of cluster exposure to sunlight on fruit composition of ‘Norton’ grapes was studied. Three exposure levels, such as fully exposed, partly exposed, and fully shaded, were established by canopy management practices, such as shoot positioning, shoot thinning, and leaf removal. Row orientation significantly impacted fruit composition with east west orientation and resulted in high total soluble solids, anthocyanin, and tannin content. Titratable acidity, total phenol, and juice potassium was highest in vines planted in north south row orientation. Fully shaded clusters had the lowest total soluble solids, lower glucose and fructose content, and highest juice potassium and malic acid content. Fully exposed clusters displayed lowest titratable acidity. Fully exposed clusters on the west and south side of the canopy received photosynthetically active radiation of more than 1,100 μ mole m-2 sec-1, while partly exposed and fully shaded clusters received less than 10% of total photosynthetically active radiation at solar noon. Berries on fully exposed clusters exhibited a temperature that was about 10–15°F higher than air temperature, while fully shaded clusters were about 1–2°F higher than air temperature.

# Quantitative Analysis of Phytic Acid in Grape Seeds, Stems, and Berries of Cabernet franc and Petit Verdot {#article-title-2} Phytic acid is a strong chelator and antioxidant naturally present in plant seeds. It has been shown to help prevent metal cation catalyzed oxidation and improve protein

# Cluster Thinning Affects Fruit Composition and Economic Sustainability of Riesling {#article-title-2} Cluster thinning (CT) is applied to reduce grapevine crop load and advance ripening parameters, but it also increases production costs and lowers yields. Riesling vines were subjected to four

Industry involvement is a critical aspect of the Specialty Crops Research Initiative (SCRI). Both a mandate for need and funding are necessary from industry to develop a successful SCRI project. The National Grape and Wine Initiative (NGWI), a nationwide coalition representing all segments of the grape ( Vitis sp.) industry including raisin, juice, fresh grape and wine interests, identified extension education as a critical need and charged its extension/outreach committee to concentrate on ensuring industry members are aware of and have access to findings from grape and grape products research. To achieve this goal, the committee decided that a comprehensive online information and educational resource would play an important role. In 2009, the eXtension Grape Community of Practice (GCoP) was funded by the SCRI. The NGWI was active in soliciting letters of endorsement and buy-in from the industry for the project. The Missouri Wine and Grape Board (MWGB) also contributed $20,000 per year for three years to help offset the matching requirement. Research-based grape proposals in subsequent rounds of the SCRI in 2010 and 2011 wishing to have the approval of NGWI have been strongly encouraged to include the GCoP as a portion of their extension component. For the 2011 round of SCRI proposals, this led to the GCoP being included in three projects, two of which were funded. Exploration of future avenues for funding will include subcontracts from other grant awards, NGWI, industry sponsorships, and other creative methods.

Balanced, dormant hand pruning was compared with minimal and machine box-cut pruning with no fruit thinning, thinning at 27 to 45 days postbloom, or thinning at veraison on Vitis labruscana grape cultivars, Concord and Sunbelt. Weekly berry weights measured during the growing season showed that minimally pruned ‘Concord’ and ‘Sunbelt’ generally had lower berry weights than hand-pruned vines. Lag phase occurred 50 ± 7 days postbloom in ‘Concord’ and 58 ± 7 days postbloom in ‘Sunbelt’. The duration of harvest period was longer for ‘Concord’ than ‘Sunbelt’, and minimally pruned vines without thinning had the most delayed ripening regardless of cultivar or time of fruit thinning. The desired soluble solids of 17% for ‘Concord’ and 18% for ‘Sunbelt’ were achieved without differences in other fruit composition parameters on all treatments. Delaying harvest of minimally pruned vines without thinning by about 7 days was required to achieve the desired soluble solids. Pruning methods had more effect on yield components than time of thinning. At harvest, minimally pruned vines had lower cluster weights, berry weights, and yield per node compared with hand pruning in both cultivars and years. In terms of second year yield response, ‘Sunbelt’ was not as detrimentally impacted by machine and minimal pruning without thinning compared with ‘Concord’. Preliminary results indicate that machine and minimal pruning with and without thinning are viable alternatives to hand pruning for ‘Concord’ and ‘Sunbelt’ grapes in irrigated vineyards with warm, long growing seasons.