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Introduction |
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The two most important decisions a grape grower makes are the vineyard location and choice of scion and rootstock. In New York, very few varieties of Vitis vinifera the European wine grape are commercially grown. Only Chardonnay and White Riesling are planted in sufficient acreage for the State Crop Reporting Service to report separate production records. Those two varieties are from the most northerly grape growing districts of Europe, and are characterized by cold hardiness, early wood and fruit maturation and exceptional wine quality. In recent decades German grape breeders have produced several new and promising wine varieties for their northern climate. Most were selected to supplement a culture based upon White Riesling and Müller-Thurgau and as such, they offer potential to New York grape growers. Over the last 14 years, these varieties have been imported into North America and New York. This bulletin summarizes our observations on their performance across the state.
Parallel to the importation of these "new" varieties, vinifera culture began to spread in New York. The Finger Lakes production area of central New York has been the center of vinifera production since the pioneering work of Charles Fournier and Konstantine Frank. From 1977-1987, increasing interest was expressed in culture of vinifera in other production areas of the state. Notable during this time was the emergence of Long Island as a significant production area.
In order to understand the potential of these new areas and to explore the adaptation of the "newer" varieties in New York state, grape plantings were established in 1981-82 at four locations in the state: Finger Lakes (New York State Agricultural Experiment Station, Geneva), Chautauqua/Erie (Vineyard Laboratory, Fredonia), Long Island (Long Island Horticultural Research Laboratory, Riverside) and Hudson Valley (John Nicklin Orchards, Marlboro). A different mix of varieties was tested at each location. The variety list for a given region was based on assumed site limitations due to winter cold and length of growing season and upon the extent of space available. All varieties were tested at Geneva in the Finger Lakes.
Unlike some commercial production areas, weather is a variable in New York grape production. Different growing seasons result in different levels of winter hardiness. Summers are longer or shorter, hotter or cooler. Most vineyards depend on rainfall for the moisture required for vine growth and development. In some years rain, especially at harvest, can be excessive. In other years it can be scant and vines may suffer from water stress. Weather during the test period is summarized in the appendices.
Tests resulted in yields in the range 2.5-4 tons/acre for several of the well known varieties. This indicates that, with good site selection and careful viticulture, commercial culture of vinifera varieties is a viable option for New York growers.
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Culture methods were based on those described in Cornell Special Bulletin 111, Commercial Culture for NY Vineyards. They were modified to ensure vine survival in spite of potential winter injury and to maximize assurance of data availability. Unless otherwise noted, the rootstock used was Couderc 3309. Vines were planted 8 feet (2.4 meters) apart in 9 foot (2.7 meter) rows. At each location varieties were planted in 3 vine (post length) plots using 4 plots/location/variety in a randomized complete block design.
Cultural practices were similar at the three colder locations (Fredonia, Geneva and Marlboro). At these locations the training system was Modified Keuka High Renewal. Multiple (4-6) trunks were used so those affected by crown gall or winter injury could be removed without decreasing the fruiting potential of the vine. An attempt was made to replace at least one trunk of every vine every year. Graft unions were covered during the winter to ensure survival of some scion buds. Additionally at Fredonia and sometimes at Geneva, selected renewal canes were buried for winter protection. Data for bud survival is from non-buried canes. Weed growth in the row was controlled with herbicides after removing the hill in the spring. Between row floor management usually consisted of clean cultivation from bud break until mid-summer, when weed growth was allowed to develop or a cover crop of annual grass was sown. In Geneva in 1987, glyphosate was applied to the row middles in late May. When plant growth required it, row middles were mowed to prevent excessive competition.
Several of these practices were modified at the Long Island site. There, Hudson River Umbrella (top wire bilateral cordon) training was used, usually with two trunks per vine. Graft unions were not covered during the winter and double trunks were established and only replaced when required.
At all locations double pruning was practiced. Vines were rough pruned in late winter leaving approximately double the number of canes required. Following bud break, when bud survival and mortality were apparent, barren nodes, base shoots and total shoot number per vine were counted. Shoot number was then adjusted using a 20+20 pruning formula (20 shoots were left for each pound of cane prunings). Vines having less than 0.5 lb cane prunings were de-fruited. No more than 60 shoots were retained/vine. Pest control spray programs followed the Cornell University recommendations. Sulfur was alternated with sterol inhibitory powdery mildew control agents (and/or benomyl on Long Island). In most years the only insecticide used was carbaryl (two applications). In order to control Botrytis cinerea., Ronilan or Rovral was applied starting when the fruit reached 5% soluble solids. In Geneva and Marlboro no nitrogen fertilizer was added, but 20 lbs/acre actual N was applied in most years to the other two locations. When 2 year old vines growing at Fredonia and Long Island showed symptoms of nutrient imbalances associated with low soil pH, pH was raised by addition of dolomitic limestone (2 tons/acre at Long Island, 7 tons/acre at Fredonia). Target soil pH was 6.5 in the top 12 inches of soil.
At harvest, cluster number and weight were recorded. Random fruit samples were taken from each plot for soluble solids analysis. Wine samples were usually made from a minimum of 80 kg fruit by members of the department of Food Science and Technology. Wine quality was evaluated using a 10 point hedonic scale. Judges were commercial winemakers and were asked to describe wine character as well as evaluate overall quality. Results are only given for wines made from the 1987 Geneva crop.
Cold hardiness ratings were modified from those previously used in New York (see reference 18) which describe hardiness of the genus Vitis rather than cultivars of the single Vitis species, Vitis vinifera. A 5 point numeric rating is combined with a descriptive classification such as hardy or tender. The rating of 5 (hardy) is relative to the highest level of adaptation we have observed in our tests of vinifera varieties. Poorly adapted varieties which regularly suffered cold damage to buds or trunks at all locations received a rating of 1 (very cold tender). Laboratory derived estimates of the mid-winter median killing temperature of Geneva grown buds were obtained using the technique of Wolf and Pool (see reference 20).
In some cases special disease susceptibility is noted. Vinifera varieties are all susceptible to several fungal and bacterial diseases. Notes refer to incidents that occurred in spite of excellent, disease control spray programs.
Research on variety and clonal adaptation, trellis design, pruning systems, harvest criteria and other cultural variables involved in commercial cultivation of vinifera are continuing. Results and conclusions will be reported in other bulletins in this series.