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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 ownrooted (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', 'Selection 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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Recent and severe droughts in major grape (Vitis)-growing regions of the United States and Australia underscore the importance of more efficient agricultural use of water. Grape rootstock breeding for increased drought tolerance could contribute to continued sustainable yields as fresh water supplies decline. Rhizotron containers were used in a greenhouse to investigate the predictive measures of drought tolerance in young grapevine rootstocks. Deeper rooting distributions were found for the drought-tolerant rootstocks '110R' (Vitis berlandieri × Vitis rupestris) and 'Ramsey' (Vitis champinii, a natural hybrid of Vitis candicans × V. rupestris) as opposed to shallower distributions observed in the more drought-sensitive rootstocks '101-14Mgt' (Vitis riparia × V. rupestris) and 'Riparia Gloire' (V. riparia). Production of new roots during a 6-day nonirrigated period declined 45% to 53% for 'Riparia Gloire' and '101-14Mgt', respectively, but showed no change in '110R' and 'Ramsey'. Slow growth, a hallmark of abiotic stress tolerance, was evident in the drought-tolerant rootstocks in their relatively slow shoot growth before drought stress and their relatively slow new root growth during recovery, especially for 'Ramsey'. High stomatal conductance (gS) corresponded with drought tolerance and distinguished rootstocks best during the first 3 days of recovery, with a mean value for 'Ramsey' 2.7 times higher than '101-14Mgt'. Stomatal conductance during recovery may serve as the most efficient means of predicting drought tolerance capacity in a breeding program. [ABSTRACT FROM AUTHOR]

Vine growth and yield variables were measured for grape (Vitis vinifera) planted as green-growing and dormant 'Chardonnay' benchgrafts during the first 8 years after vineyard establishment. Benchgrafts of 'Freedom' and 'Kober 5BB' rootstock were evaluated. Vines planted as green-growing benchgrafts had smaller trunk and cordon diameters and lower pruning weights. Growth variables measured were higher for 'Freedom' benchgrafts than 'Kober 5BB'. Yields were higher for vines planted as dormant benchgrafts in three of the first six production years when compared with vines established with green-growing plants. Productivity was higher for vines planted with dormant benchgrafts or grafted on 'Freedom' rootstock because the permanent framework of vines in these treatments was fully developed earlier in the training process, which allowed for earlier crop production. [ABSTRACT FROM AUTHOR]

Growers in California's San Joaquin Valley produced >25% of the world's raisins in 2012, with a farm-gate value of >$590 million, making the United States the leading global producer of raisins. California's traditional raisin-making method is a laborious process in which clusters of grapes (Vitis vinifera) are harvested by hand onto paper trays, which are left in the vineyard to dry. The drying fruit may need to be turned or rolled, tasks requiring manual labor, and the trays of dried raisins are also picked up by hand. Most California raisins continue to be made in this way, but in recent years, the declining availability and increasing cost of labor has prompted many growers to implement one of two mechanized production systems, "continuous tray" (CT) or "dry-on-vine" (DOV). In CT systems, machines are used to pick the berries, lay them onto a tray, and pick up the dried raisins. The CT system could be considered a short-term strategy: it is compatible with existing conventional 'Thompson Seedless' raisin vineyards and has been widely adopted. The DOV system could be considered a medium-term strategy: it is best suited for vineyards specifically designed for DOV, with early ripening grapevine cultivars on expansive trellis systems, which ensures timely drying, and capitalizes on the fact drat sunlit row middles are not needed for fruit drying. Grapevine breeding programs are currently working toward the development of raisin grape cultivars with fruitful basal nodes, with fruit that dry naturally upon ripening. This is a long-term strategy to further reduce labor needs by enabling mechanical pruning in winter and eliminating the need for cane severance in the summer. [ABSTRACT FROM AUTHOR]

A geographic information system (GIS) application was developed containing 18 layers of spatially explicit environmental data relevant to characterization of the eight officially recognized American Viticultural Areas (AVAs) for wine grape (Vitis vinifera) production in Texas. GIS climate variables included daily minimum temperature, daily maximum temperature, daily average temperature (TAVG), growing degree days (GDD), ripening period mean temperature (RPMT), annual precipitation, solar radiation, vapor pressure, and number of frost days. Soil attributes were texture, depth, available water capacity, pH, permeability, and bulk density. These data were used to develop interpretative descriptions of Texas AVAs published on the Winegrowing Regions of Texas web site, which also serves as the public portal to the interactive GIS (AVATXIS). Individuals can use AVATXIS to access data and visualize spatial variability on maps to characterize Texas AVAs for any or all of the environmental factors and to examine spatial relationships among factors. [ABSTRACT FROM AUTHOR]

Junior college (JC) and community college (CC) programs offering viticulture and enology courses have proliferated in recent years in many states, especially outside of traditional grape growing regions. A survey was sent to 69 land-grant (LG) horticulture, viticulture, and enology specialists who may interact with JC and CC programs offering viticulture and enology courses. Forty answered for a response rate of 58%. Results indicated that most LG horticulture/viticulture programs are not interacting with the JC/CC programs and that LG specialists do not believe the education received by students of the JC/CC program is sufficient to create well-trained industry professionals. JC/CC programs are generally regarded as positive for the viticulture and enology industry by LG specialists, but some question the quality of instruction. Many LG respondents do not believe the JC/CC programs arc impacting their own programs and do not see the JC/CC programs as competitors to their programs; however, documented actions of JC/CC programs would dictate otherwise, especially in the area of Cooperative Extension programming. LG viticulture and enology programs should no longer consider JC/CC programs as noncompetitors for funding and clientele interaction, especially in states with limited resources. LG programs should seek to develop appropriate partnerships with JC/CC programs to benefit the viticulture and enology community. However, any collaboration must be mutually beneficial, well-designed, well-coordinated, and conducted with reciprocal respect for each program. [ABSTRACT FROM AUTHOR]

Airborne multispectral image data were compared with intercepted photosynthetic photon flux (PPF) in commercial winegrape (Vitis vinifera) vineyards of Napa Valley, Calif. An empirically based calibration was applied to transform raw image pixel values to surface reflectance. Reflectance data from the red and near-infrared spectral regions were combined into a normalized difference vegetation index. Strong linear response was observed between the vegetation index and PPF interception ranging from 0.15 to 0.50. Study results suggest the possibility of using optical remote sensing to monitor and map vineyard shaded area, thus providing spatially explicit input to water budget models that invoke evapotranspiration crop coefficient based calculations. [ABSTRACT FROM AUTHOR]

The ability to monitor plant nutrient status of high value horticultural crops and to adjust seasonal nutrient supply via fertilizer application has economic and environmental benefits. Recent technological advances may enable growers and field consultants to conduct this type of monitoring nondestructively in the future. Using the perennial crop apple (Malus domestica) and the annual crop potato (Solanum tuberosum), a hand-held leaf reflectance meter was used to evaluate leaf nitrogen (N) status throughout the growing season. In potato, this meter showed good correlation with leaf blade N content. Both time of day and time of season influenced leaf meter measurement, but leaf position did not. In apple, three different leaf meters were compared: the leaf spectral reflectance meter and two leaf greenness meters. Correlation with both N rate and leaf N content were strongest for the leaf reflectance meter early in the season but nonsignificant late in the season, whereas the leaf greenness meters gave weak but significant correlations throughout the growing season. The tapering off of leaf reflectance values found with the hand-held meter is consistent with normalized difference vegetation index (NDVI) values calculated from satellite images from the same plots. Overall, the use of leaf spectral reflectance shows promise as a tool for nondestructive monitoring of plant leaf status and would enable multiple georeferenced measurements throughout a field for differential N management. [ABSTRACT FROM AUTHOR]

Snack time [ABSTRACT FROM PUBLISHER]