Vineyard and Winery Information Series:
Vol. 16 No. 5, September-October 2001
Dr. Tony K. Wolf, Viticulture Extension Specialist
II.Question from the field
Each year is unique. The 2001 season was no exception. Better perhaps than average, the season positives, here at Winchester, were average to somewhat below average rainfall, a very dry September-October grape ripening period, and cooler than average temperatures. The long-term mean maximum July temperature at Winchester is 87° F. This year it was 83.5°F. Negatives, reported by some around the State, included some spring frosts, some localized hail damage, localized, heavy rains in September, and "early" frosts for some northern Virginia vineyards the week of 8 October. Birds and deer were significant problems in a few cases.
As of this writing, our Cabernet Sauvignon is still on the vines, but will likely be picked the last week of October. At 950 to 1000 feet elevation, our vineyard narrowly escaped the frosts of early October. For the most part, we have been extremely pleased with fruit quality and we've collected heaps of data from our training system comparison, Chardonnay clone comparison, Chardonnay and Cabernet crop load studies, Danielle LoGiudice's plant growth regulator (Apogee®) experiments, as well as some smaller scale studies. Summaries of these projects will be forthcoming here, or at our winter meeting in Charlottesville (see Coming Meetings). Viognier continues to be a bright star, with very high sugars, good varietal character, and up to 5.4 tons/acre (equivalent) on our Smart-Dyson training. Our Traminette, despite overcropping at over 9 tons/acre on Smart-Dyson, was picked at 23.8 with a pH of 3.2. Traminette is a rising star. We were simply lucky this year and we will have to do a better job of crop control next season. One less than optimal feature of some of the northern Virginia fruit (Chardonnay and Cabernet, anyway), including ours, has been relatively high (7 to 10 g/L) titratable acidity, presumably a function of the cooler than average temperatures. Stay tuned.
Commercial Grape Report for Virginia: The Virginia Agricultural Statistics Service will again be collecting Virginia grape acreage and grape production data. Those with commercial vineyards should receive the survey questionnaire within the next week or so. Please take a few minutes to complete and return the survey. In addition to production and variety data, this year's survey includes questions about prices paid for grapes. We are told that the 2001 Virginia grape data will make it into the federal crop report. A review of the current, federal crop report (http://www.usda.gov/nass/pubs/agstats.htm) suggests that Virginia currently ranks number six, nationally, in terms of grapes used in wine production.
Please contact the VA Agricultural Statistics Service (800-772-0670) if you grow one or more acres of grapes (bearing or non-bearing) and you do not receive a Virginia Commercial Grape Production Survey by 1 December 2001. Why should you care? State agencies such as Virginia Tech and Virginia Department of Agriculture and Consumer Services use the composite data to monitor industry growth, document program impacts, and to justify fiscal and personnel resource expenditures. There are efforts underway, for example, to augment Virginia Cooperative Extension's support of the Virginia wine and grape industry. To succeed, those efforts must ultimately be supported by the Virginia General Assembly as worthwhile initiatives. Documentation of the growth of our industry, and potential for further growth, are positive means of supporting that process. Your input is essential for accurate data.
Results of crop estimation workshop: Attendees of the crop estimation workshop held at Ivy Creek Vineyards near Charlottesville on 2 August were told that a comparison of estimated vs. actual yield would be forthcoming. Crop was estimated on a 0.8-acre block of lyre-trained Chardonnay with the help of attendees. Estimated vs. Actual yield data were:
Estimated: (0.33 lbs/cluster) x (202 clusters/panel) x (140 panels/block) x (1/2000) = 4.67 tons Actual: 5.42 tons
We underestimated crop by about 16%, which was likely due to variability in the counted clusters per panel, cluster weight, or both. Ivy Creek's Paul Mierzejewski indicated that a small sample of clusters at harvest revealed an average cluster weight closer to 0.30 lbs. If we plug that cluster weight, and the 5.42 actual tons/acre into the above equation, we arrive at an average of 258 clusters/panel. So, we weren't spot on, but we were close to the 15% margin that many experienced producers aspire to achieve. Due to some confusion (I'll take blame), the crop estimation portion of the following day's workshop at Winchester was inconclusive.
A note of thanks: My sincere "thank you" to the Virginia Vineyards Association whose Board of Directors approved and provided a gift of $2,450 for the purchase of a Xerox/Tektronix color laser printer, now in service at the AHS Jr. AREC. Preparation of color reports, enhanced vineyard suitability maps, color overheads and overlays, etc. are some of tasks that I've put the printer to since we acquired it.
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Answer: I could be really nasty and suggest that you must, of course, strip the frosted leaves. But I won't, and by now you will likely have seen that the leaves have fallen on their own. So, calm down. It's improbable that the vines have actually resumed growth from buds since the frost. We are in a temperate climate, and fall frosts are a normal feature of the environment. The vines are adapted; however, a killing frost suspends further carbohydrate production and periderm or bark development on canes. Instead of seeing canes with uniform bark development out to 10 or 15 nodes, the frosted vines may only have a few nodes per cane that have "hardened off," and there may be considerable cane to cane variability in the extent of ripening. Except for possibly "hilling-up" vines, there's not much you need to do until vines are pruned, at which time you'll need to determine the viability of wood you wish to retain. I would wait until late-winter to prune. Because your vines are first-year vines, you may find it necessary to go back close to the graft union to find viable cane tissue. Over the last couple of years we've had many reports, and have seen first-hand, situations where what appeared to be visibly matured canes were, in-fact, damaged by low temperatures. A good discussion by Bob Pool of Cornell University on recognizing and dealing with cold injury to canes and trunks can be found at: http://www.nysaes.cornell.edu/hort/faculty/pool/trunkinjury/tihtml/trkinjtablecontents.html
As a generality, we can say that the early frost and resulting defoliation reduced the potential of the vines to reduce winter cold injury. Some die-back of canes would occur under the best of conditions. More die-back might occur in your situation than had the vines had another month of growing season. You can, as an insurance practice, provide some measure of protection against actual vine loss by hilling the graft unions and a few inches of canes with soil this fall, before the advent of damaging low temperatures. A detailed description of this process can be found in last year's Sept-Oct. Viticulture Notes, or at: http://www.ext.vt.edu/news/periodicals/viticulture/00septoct.html#I
In essence, the soil insulates the covered portion of the vine from cold injury, but it will ultimately lead to scion rooting if the soil is not removed the following spring. The above-mentioned article describes the negatives of hilling-up, not the least of which is the labor involved, and/or cost for purchase of a specialized plow or grape-hoe. Some grapevine nurseries, such as American Nursery here in Virginia, recommend hilling-up all grafted vines during their first few years in the vineyard. I cannot argue against that recommendation, particularly if you're in a new situation where the site experience with previous winters is lacking.
Initial treatments were made on 5 July 2001, when Chardonnay berries were at a modified Eichhorn-Lorenz stage of 32-33 (just before bunch closing). Vangard was applied at the label recommended rate of 10 oz/acre equivalent and the yeast was applied at a similar rate and water volume. Controls were not treated. All treatments received a typical fungicide spray program, however Vangard and other Botrytis-specific fungicides were not used in the general vineyard maintenance sprays. Yeast and Vangard were reapplied at veraison (2 August) (same rates and methods), and yeast was reapplied weekly until 10 days before harvest. Ratings of botrytis incidence and severity were done on 23 August and 27 September, the results of which are summarized in Table 1. Because the yeast is not a registered pesticide, I picked the yeast-treated fruit on 27 September and discarded it. The principal interest of the study was to evaluate the efficacy of the yeast as a biofungicide. In that regard, the yeast did reduce the incidence and severity of botrytis as originally rated on 23 August. The majority of botrytis appeared to be due to a combination of hail damage from an early-July storm, and from some grape berry moth feeding. While the yeast appeared somewhat effective at botrytis control, the more dramatic result was the near-complete, and persistent control of botrytis by Vangard. Vangard has been discussed for botrytis control in previous newsletters, and there is a justifiable concern that overuse of Vangard can result in botrytis resistance to the fungicide. We used it at label rates and timing and would not necessarily advocate its use every season. While we do not advocate or endorse Vangard to the exclusion of other products, the results of this small-scale trial highlight its value in an overall botrytis bunch rot management program.
Table 1. Incidence and severity of botrytis bunch rot of Chardonnay in response to conventional (Vangard) or yeast biofungicide treatments. Incidence is the percent of clusters with at least 5% affected berries. Severity is the average percentage of affected berries on affected clusters. Data are averages of five replications per treatment. September 27 was two days prior to commercial harvest.
|23 August 2001||27 September 2001|
|Treatment||Average incidence (%)||Average severity (%)||Average incidence (%)||Average severity (%)|
|Control||37.0 a||18.8 a||58.2 a||11.5 a|
|Yeast||21.6 b||8.2 b||46.0 a||10.4 a|
|Vangard||2.2 c||4.0 c||3.2 b||0.6 b|
Means within columns followed by different letters are significantly different, P < 0.05, Tukey's Studentized Range.
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14 -- Pennsylvania Association of Winegrowers (formerly SEGA) Fall Meeting and Dinner. Lancaster Farm and Home Center in Lancaster, PA. A strategic plan for PAW and the vineyard community in Pennsylvania will be discussed. PAW will hold a general membership meeting. Dinner will be at Gibraltar in Lancaster. For information and registration, please call Mark Harris 610 255-4101 or Nelson Stewart 717 993-5077.
4 -- Pruning Workshop. Manatawny Creek Winery and Vineyard, Douglassville, PA (Berks County). This workshop will cover all aspects of pruning grapevines at a commercial vineyard. Registration fee is $10. Please contact Mark Chien at 717 394-6851. Bring pruning shears, warm clothes and hot drinks.
10 - Long Island Ag Forum presented by Cornell Cooperative Extension. Riverhead, NY. Topics will focus on irrigation and advanced viticulture. Jeff Newton of Coastal Vineyard Care in Santa Barbara County and Kevin Ker from Ontario will be the main speakers. Contact: Alice Wise, 631-727-3595.
15-17 - Wine Business and Marketing Shortcourse offered by Penn State Cooperative Extension, Pennsylvania Wine Association and Clover Hill Vineyards and Winery. Nittany Lion Inn in State College, PA. Registration is $250. A comprehensive three-day business and marketing shortcourse led by two wine business faculty from Adelaide University in Australia. Call Kari Skrip for registration and information at 888 256-8374.
19-21 - Same course as 15-17 Jan. at the Penn Stater in State College, PA. Same contact.
29 - Wine Grape Section of the Mid-Atlantic Fruit and Vegetable Convention in Hershey, PA. The theme for the meeting will be Vine Decline in Eastern Vineyards. Laura Mugnai from the University of Florence will be our keynote speaker. Other speakers include: Dr. Elwin Stewart, Ms. Lucie Morton, and Dr. Jim Travis. Dr. Tom Burr from Cornell will talk about his crown gall research. Joachim Hollerith and Herman Amberg will talk about how nurseries can help provide growers with clean vines. Call Mark Chien 717-394-6851 (email@example.com) for more information.
29-31 - Unified Symposium. Sacramento, CA. A very large trade show accompanies this grower oriented meeting. More information at http://www.asev.org/ or ASEV, 530-753-3142 (Society@asev.org).
2 - Annual meeting, North Carolina Grape Growers Association, Greensboro, NC. Contact: http://www.ncagr.com/markets/commodit/horticul/grape/Ncwa.htm or Andy Allen 919-515-2505 (firstname.lastname@example.org).
14 -16 - Annual winter meeting of the Virginia Vineyards Association, Omni Hotel, Charlottesville, VA. Conference will include discussions of vineyard nutrition, disease management, research updates, with speakers from NY, Ontario, and Virginia. Program details will be mailed in December. Tony Wolf (email@example.com).
23 - 53rd Annual Finger Lakes Growers Convention. Waterloo, NY. This annual program will focus on grape production issues in the Finger Lakes region. Call Tim Martinson for information at 315 536-5134.
12 - [TENTATIVE] New Grower Workshop presented by Dr. Tony Wolf (Virginia Tech), Dr. Joe Fiola (Univ of MD) and Mark Chien (Penn State). A full-day program for those interested in developing a commercial wine grape vineyard. Contact: Mark Chien 717-394-6851 (firstname.lastname@example.org).
10-13 - Wineries Unlimited at the Lancaster Host Resort in Lancaster, PA. This is the largest annual trade show and meeting in the east. Call Vineyard and Winery Management for information or see their web site at www.vwm-online.com.
26-28 - American Society for Enology and Viticulture Annual Meeting. Portland, Oregon. This is a fine technical meeting with many papers from viticulture and enology researchers around the world. A large trade show is also part of the event. You can find information at http://www.asev.org/.
If you are a person with a disability and desire any assistive devices, services or other accommodations to participate in this activity, please contact the AHS Agricultural Research and Extension Center, at 540-869-2560 during business hours of 7:30 am to 4:00 pm weekdays, to discuss your needs at least 7 days prior to the event.
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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 would like to receive "Viticulture Notes" as well as Dr. Bruce Zoecklein's "Vinter's Corner" by mail, contact Dr. Wolf at:
Dr. Tony K. Wolf
AHS Agricultural Research and Extension Center
595 Laurel Grove Road
Winchester, VA 22602
or e-mail: email@example.com
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