Vol. 13 No.6, November - December, 1998
Dr. Tony K. Wolf, Viticulture Extension Specialist
Springtime in December??: December 7, a day of infamy indeed the hottest December day on record in Washington, DC (79° F). Projections for the Virginia winter are warmer and drier than average, compliments of La Niña. That forecast has certainly been borne out to date. Passed thru the DC area yesterday and saw forsythia and an ornamental plum tree in full bloom. Our grapes have more sense. Really. We tested cold hardiness of Chardonnay buds and canes on 3 December. At that time, our vines lost 50% of primary buds at a temperature of 0° F. This was our first freezing test of the season, and I was initially amazed that the tissues (canes showed about the same freezing resistance) were that cold hardy. We are currently freezing Cabernet Sauvignon canes, but the data wont be ready in time for this newsletter. Nevertheless, I suspect about the same degree of cold hardiness. In the late-eighties, a colleague in New York (Bob Pool) and I sought to determine the most important environmental features that contribute to vine cold hardiness. Genotypic components (e.g., variety and species) were recognized for their obvious importance and were quantified as well. On the Virginia front, I was also interested in being able to predict the level of cold hardiness given daily temperature information. Regression analysis was used to predict bud cold hardiness based only on daily low temperatures and days from a standardized start point (1 September). The resulting models were fairly accurate at predicting the average freezing temperature of Cabernet Sauvignon and Riesling buds into early January (the subject was discussed in the Jan-Feb., 1994 Viticulture Notes). Based on the Cab. Sauvignon regression model developed in the late-eighties, we can predict that our Cabernet Sauvignon at Winchester would sustain about 50% bud kill if temperatures dropped to 1.2° F now (8 December). This is only one to two degrees (F) less hardy than actually measured for this time in recent falls. Despite the drought, we had excellent post-harvest wood "ripening" weather and our first frost did not occur until 5 November. In sum, based on the test of Chardonnay, and the predicted Cabernet Sauvignon cold hardiness, Im not too worried about the recent, unseasonably warm weather.
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Chardonel is a hybrid wine grape that resulted from a cross of Seyval and Chardonnay made in 1953. The named variety was released by Cornell University in 1990. We included Chardonel in our original planting of 25 wine grape varieties in 1989, and it performed very well in the field and in terms of high wine quality. Fruit is similar to Seyval, but tends to have better pH and acidity levels than Seyval, for a given soluble solids concentration. Our Chardonel, planted at 7 vine spacing, have averaged 4.5 tons per acre (equivalent), with a soluble solids of 23.5 and pH of 3.4 (our pH units tend to be elevated by 0.1 to 0.2 pH units because analyses are performed on berry samples that had been frozen). In my opinion, Chardonel is superior to Seyval in at least two respects. First, we have had essentially no bunch rot problems with Chardonel. In contrast, Seyval is highly susceptible to mid-cluster botrytis bunch rot problems. Secondly, Chardonel does not have the propensity for over-cropping exhibited by Seyval. After shoot thinning, we have not had to do any subsequent crop removal to keep crops at or below 5.5 tons per acre. Our Seyval crops, by comparison, often exceed 6.0 tons/acre (equivalent) at the same vine spacing, and have been as high as 9.0 tons/acre, even with extra "crop control." I will not argue that Seyval may, however, be more recognizable to wine consumers than "Chardonel."
We have, however, observed a problem with Chardonel. Beginning in 1996, we noticed one vine (out of 15 total) that showed peculiar problems: fruit maturity was advanced, leaves showed premature yellowing towards the end of summer, and shoot growth ceased well before that of other Chardonel. That particular vine had reduced cane pruning weights and ultimately was removed during 1997. An additional three Chardonel showed similar symptoms in 1997 and 1998. After some discussion with Lucie Morton, who suggested we start with the obvious, we dug some affected vines and yes, phylloxera were abundant on the roots. Our Chardonel, like other hybrids in our trial, were own-rooted. Affected vine samples were sent to the Plant Disease Clinic at Virginia Tech. The clinics report confirmed the presence of phylloxera, and showed no evidence of other pests or pathogens. Upon reflection, the affected vines did exhibit the symptoms of phylloxera feeding on vines grafted to AxR#1 rootstock that Id seen in Napa Valley vineyards. It would appear, then, that Chardonel is not sufficiently tolerant to phylloxera at our site. The original release note (Reisch, 1990) for Chardonel indicated that own-rooted vines are "productive and moderately vigorous" when grown in phylloxera infested soils. In subsequent personal communication, Dr. Bruce Reisch, who released Chardonel, has warned that because Chardonel is at least 50% vinifera, one should be cautious about planting Chardonel anywhere on its own roots. We will continue to recommend Chardonel in Virginia; however, the recommendation will include the provision that it only be used with a suitable rootstock. Expanding this concept, I would also include other hybrids, such as Traminette (see VN, Vol. 11, No. 4) in this recommendation. While these hybrids may perform well on their own roots in the short-term, why risk their long-term survival? Use a rootstock. Sure, it adds time and cost, but a vineyard IS a long-term investment. As an aside, we planted own-rooted Traminette, along with Traminette grafted to C-3309 rootstock in a training system comparison in 1998. If Traminette behaves like Chardonel, it may take eight to 10 years to determine the relative merits of using a rootstock.
Reisch, R.I., et al., 1990. Chardonel grape. NY Food and Life Science Bull. No. 132., NYSAES, Geneva, NY. 3p.
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"I plan to plant 8 acres of Chardonnay next spring. The nursery is asking what clone I want? What do I tell him?" Variations of this question arise each year, and not just for Chardonnay. Most commonly planted varieties have numerous sub-sets, called clones, available. Briefly, clones originate when someone either intentionally or unintentionally makes a field selection of a unique vine from a larger population. The unique selection criterion might be higher yields, better fruit flavors, improved disease resistance or other, apparently superior traits. How a particular vine achieves unique performance within a population is not certain, but mutations, somaclonal variation, or presence of viruses and other agents may cause the variation. The superior vine is vegetatively propagated, and all subsequent cuttings are clones of the original mother vine, provided the identity is conserved. The clone is either named or, more typically, numbered during this process. Clonal variability that is, the variation in qualitative or quantitative characteristics between clones of the same variety offers the winemaker a unique wine, or a unique blending component of a clonal assemblage. For the grape grower, who might have struggled with a variety decision, the subject of clones can be perplexing. Varieties such as Pinot noir and, increasingly, Chardonnay, have a bewildering array of commercially available clones. Research and experience in the East with many of these clones is simply lacking.
With funding from the Virginia Winegrowers Advisory Board, we established a planting of 10 Chardonnay clones at the Winchester Agricultural Research and Extension Center in 1998. Suffice it to say, if we had a definitive answer to the above question, we would not have gone to the expense and time to establish this trial. We anticipate data collection starting in 2000, continuing through 2007 at minimum. The Chardonnay clones included in our trial are: #4, #5, #6, #15, #17, #25, #76, #95, #96, and #277. Based on the experience, research, and opinions of others, and given our own space limitations, I felt that this collection was a good representation of the Chardonnay clonal variation that existed in 1995 (The project was designed in 1995. Grafting and a failed year due to spring frost to our nursery delayed establishment until 1998). Clones #4, #5, #6, and #15 are Foundation Plant Material Service (FPMS) clones. Clones #76, #95, and #96 are French "Dijon" clones. Clones #17 and #25 are proprietary. Clone #277 is also from France and available commercially. Our "standard" for comparison is clone #4, which weve grown since 1989. Clone #4 is perhaps the highest yielding, commonly available Chardonnay clone. A summary of our clone #4 data were presented in the Nov.-Dec., 1997 Viticulture Notes. Wine quality is good, but perhaps not as interesting as some of the other clones. The general interest in clones led to sponsorship of an International Symposium on Clonal Selection in 1995 by the American Society for Enology and Viticulture (ASEV). A 163-page proceedings from this symposium is available from the ASEV (http://www.ajev.com/society.htm). One of the "take-home" messages of the ASEVs Clonal Symposium was that the vineyardist is advised to plant several clones in their vineyard. So, an 8-acre vineyard of Chardonnay might be planted to 2 to 3 acres each of several clones. Be sure to keep the clones separate and permanently identified in the vineyard and in your records. Differences in fruit maturity date preclude the notion of mixing the clones in the vineyard. The basic philosophy here is that from year to year, the unique features of each clone will produce a synergy that results in a more complex, and hopefully superior wine, than one made from a single clone. Theres a practical limit to how small a planting should be planted to multiple clones. If you were only planting one or two acres of Chardonnay, I would probably recommend only one clone. So, given your interest in 8 acres, I might recommend equal amounts of clone #4, clone #15, and clone #95. Understand that this is a recommendation based only on comments and limited research from other areas, including Long Island (A. Wise, personal communication), Oregon (S. Price, personal communication) and California. The choice reflects our generally good results, but high yields, with clone #4, more moderate yields (Wolpert et al., 1994) and lower botrytis bunch rot problems (Vail et al., 1998) with clone #15, and a perceived very high wine quality with clone #95 (multiple sources). A different recommendation may be proffered in five to 10 years when we amass enough data from our own project. As an aside, we have also established 6 clones each of Merlot and Cabernet franc, as well as 3 clones of Petit Verdot. Again, youll have to wait five to 10 years for results.
Vail, M.E., J.A. Wolpert, W.D. Gubler, and M.R. Rademacher. 1998. Effect of cluster tightness on Botrytis bunch rot in six Chardonnay clones. Plant Disease 82:107-109.
Wolpert, J.A., A.N. Kasimatis, and E. Weber. 1994. Field performance of six Chardonnay clones in the Napa Valley. Am. J. Enol. Vitic. 45:393-400.
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Bruce Zoecklein and I had the opportunity to tramp through vineyards and wineries of northeast Spain and Southeast France this past October. The trip was organized by the Kentucky Vineyard Society and was comprised of a dozen growers, vintners, researchers and wine aficionados. Our French host and principal trip organizer was Pascal Durand, professor of agricultural economics at the University of Burgundy in Dijon. Leslie Weston, of Cornell University, was also involved in organization, and we thank both individuals for a superb program.
A significant portion on my costs was paid by the Virginia Vineyards Association, and for this I am sincerely indebted. My interest in accompanying this delegation was to observe how particular varieties were grown, and to understand more about why varieties were grown where they were. In this and subsequent newsletters, Ill relate some of our observations.
Even in late-October, the Rhône region was warm; summers are downright hot in the southern Rhône, but night temperatures are relatively cool, compared to the mid-Atlantic US. Northern Rhône is considered continental. Tain lHermitage averages (daily high-daily low/2) 37° F in January (vs. 32F in Winchester, VA) and 72F in July (vs. 75F in Winchester). Valence, an effective division between northern and southern Rhône, averages 72F in July. The highest maximum daytime temperatures during July in Valence are about 96F. The average minimum temperature is around 57F. Rainfall in September is about 4 inches about the same as Winchester, but only 1.7 inches occur in July. Irrigation is forbidden. Water stress devigorates vines, and older vines have advantages in terms of larger, presumably deeper root systems ("old" is a relative expression: for some, vines were old if more than 20 years old; others stated that old vines were those 50 or 60 years old). The region is windy, although we experienced none of the northern Mistral winds that hammer the region for up to 120 days out of the year.
Viticulture: Vines of the terraced vineyards of northern Rhône (e.g., Côte Rôtie) were planted at a density of up to 4,000 vines/acre. The steep slopes (45 to 75%) and narrow terraces mandate manual labor for all vineyard activities (helicopters for pesticide spraying are an occasional exception). Vines are trained to a low, simple Guyot system that uses a short (5 to 8 buds) fruiting cane and a renewal spur. Shoots are trained upright on a tripod frame. Elsewhere, on more level terrain, this echalas training gave way to more conventional, vertically trellised rows that were more amenable to mechanization. In the southern Rhône, and Languedoc-Roussillon, training was more often a goblet-trained vine sans trellis. Vine spacing was as dense as 3 x 3, but rows were widened to 6 where mechanical pruning and harvesting were used. Pest management was not unlike that here: powdery mildew, botrytis and phomopsis were common fungal pathogens, while grape berry moth (the European species) was a principal insect pest. The use of superior clones is a contemporary practice when vines are replanted. R-110 rootstock was nearly ubiquitous, chiefly due to its drought tolerance.
Viticulture has been pursued in this region for over 2,000 years. Post-renaissance France has had several centuries to refine viticulture to the point where specific sites are used for specific varieties. The traditionalist view, guided by the mantra of the appellation contrôlée, has resulted in the northern Rhône (e.g., Condriu, Cote Rotie) being dominated by Syrah, Viognier, and Marsanne. South of the city of Valence, in the Côtes du Rhône, Grenache, and Mourvedre are more prominent, with Syrah used in lesser proportions. Continuing south, and into the Languedoc, one finds increasing quantities of Cinsault and Carignane, along with other reds and whites that include Bourboulenc, Grenache blanc and Muscat of Alexandria. It is interesting to note that the vineyards of the Rhône region, from Vienne in the north, to Avignon in the south, stretch a scant 125 miles not much more than the distance from Charlottesville to Washington, DC. We might therefore be forgiven, in our relative youth, for still struggling with the notion of what varieties to grow in Virginia, let alone specific areas of Virginia.
Virginia, vis-à-vis Rhône: The soils are different, the training systems are different, the climates are different. Even the language is different. What can be imported from the Rhône to improve our own grape growing? Concepts, possibly. An emphasis on fruit quality was pervasive, but not universal. Exceptions in point were some of the wines at Domaine Listel, in the Languedoc, which is not part of the Rhône AC. Listel is one of the largest wine producers in the world. Their vineyards and the winery spoke of volume production, and the wines were correspondingly quite ordinary. It was at Domaine Santa Duc, in the Gigondas appellation, that the quality picture began to sharpen. Here, fruit that had been thinned from Grenache vines prior to harvest was still copiously visible on the vineyard floor. The goal of the vigneron, Yves Gras, was to keep yields at or below 1 ton/acre (much lower than the 35 hl/ha about 2.8 tons/acre permitted by AC regulations in that area). Yves wines are primarily exported and command prices commensurate with the added costs of production not that hes now rich. Fruit sorting after harvest was also common in an effort to further remove inferior fruit. Growers were well compensated for high quality fruit and for lower tonnage. While it may not be representative of the entire region, we were told at Domaine Coursodon in St. Joseph, that Syrah was worth about $2,400/ton (14 FF/kg). At Guigal, we were told by Phillipe Guigal that they purchase Viognier for 33 to 37 FF/kg (about $6,000/ton!). I do not propose such yields or such prices for Virginia. These wineries were not prospering on wines under $10/bottle, and they had little use for tourism. They were exporting much of their production and they received handsome prices for those wines.
We cannot match the terroirs of the Rhône. We can, and will, continue to seek means of improving fruit quality, whether through better variety/site matching, improved vineyard management techniques, or more patience with harvest decisions. Dr. Zoecklein and I will present a discussion of some of our observations in the Rhône region during the January 11-12 meeting.
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"Viticulture Notes" is a bi-monthly newsletter issued by Dr. Tony K. Wolf, Viticulture Extension Specialist with Virginia Tech's Alson H. Smith Agricultural Research and Extension Center in Winchester, Virginia. If you'd like to receive "Viticulture Notes" as well as Dr. Bruce Zoecklein's "Vintner's Corner" by mail, contact Dr. Wolf at:
Dr. Tony K. Wolf
AHS Agricultural Research and Extension Center
595 Laurel Grove Rd.
Winchester VA 22602
or e-mail: email@example.com
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