Viticulture Notes

Vineyard and Winery Information Series:
Vol. 18 No. 6, November-December 2003

Dr. Tony K. Wolf, Viticulture Extension Specialist

Table of Contents

I. Current situation

I call your attention to several items here in the current situation. These include an administrative change in my responsibilities, the upcoming Virginia Vineyards Association technical meeting planned for 19-21 February 2004, a major meeting being planned in Roanoke in mid-July 2004, and a web-based vineyard site selection bulletin that will be of interest to those exploring grape growing in Virginia. All of these are described in more detail, below.

Viticulture Notes newsletter: This issue of Viticulture Notes marks the 108th consecutive issue (18 years). The hardcopy version of the newsletter has been jointly distributed with Bruce Zoecklein's "Vintner's Corner." Bruce has opted to go to an all electronic distribution of his newsletter starting in January, 2004. I will likely continue a hardcopy distribution of Viticulture Notes for at least another year, but the subscription fee will be substantially increased and the mailings will not include Vintner's Corner. As an alternative to the hardcopy version, you can receive Viticulture Notes as a free subscription by subscribing electronically. Send an e-mail message to: listserv@listserv.vt.edu. Do not include a subject statement. Put one line of text in the body of the message: subscribe vce-grapenews your name. Use your actual name for "your name". Example: subscribe vce-grapenews John Doe.

Administrative changes: I have accepted an appointment as Director of the Alson H. Smith Jr. Agricultural Research and Extension Center, effective 1 January 2004. The appointment comes in part as a result of the July 2002 retirement of our former Director, Dr. Ross Byers. In the words of Dr. Gerald (Skip) Jubb, Associate Director of the Virginia Agricultural Experiment Station, "Tony will have the full responsibility and authority for operations of the AREC providing leadership for research and extension programs, preparing and managing budgets, evaluating faculty and staff performance, interacting with college and university administration, promoting the Center, and working with stakeholders. Dr. Wolf will maintain his very active research and extension program in viticulture along with his new duties as Director."

In the larger picture, the AHS AREC must diversify its programs to reflect the diversified nature of horticulture in northern Virginia. The addition of a viticulture component in 1986 (my hire) was the first departure from a strictly tree fruits oriented mission since the Center's inception. With the tree fruit industry under intense development pressure and economic stress, there is a critical need to provide assistance with alternative enterprises as producers seek diversification of farm income and retention of family farmland. The "hows" and "whats" of this AREC's diversification are not certain at this point, but in the short-term, partnerships with other horticultural faculty to include demonstration plantings of other small fruits, vegetables, landscape plant materials, and other horticultural commodities may be one avenue. We believe that a key element of this diversification will be a regional market analysis of consumers to accurately gauge what the horticultural needs and opportunities are.

As Dr. Jubb indicates, I will maintain an active viticulture research and extension program, but some activities, especially those related to individualized services, will have to be curtailed. The immediate extension activities are centered on completion of revisions to the Mid-Atlantic Winegrape Growers Guide, the continued production of Viticulture Notes, planning for workshops and a major industry meeting (see following sections), participation in VA Cooperative Extension agent-organized field meetings, and program participation on a regional basis. The more basic aspects of my extension program (site evaluation, basic problem diagnoses, routine questions, etc.) will continue to be provided by Ms. Patricia Peacock, my viticulture extension assistant. Pat can be reached at ppeacock@vt.edu or 540-869-2560 x11. Research programs, at least for the next year or two, will remain focused on three central areas: the Grapevine Yellows work with LeAnn Beanland, the variety and clone evaluations at Winchester and at the Southern Piedmont AREC near Blackstone, and the training system comparison at Winchester.

Virginia Vineyards Association Annual Meeting: The Virginia Vineyards Association has organized their annual technical meeting to again be held at the Omni Hotel in Charlottesville, 19-21 February 2004. The 2.5-day program will include a mix of viticulture, enology, and wine marketing topics. The program includes a trade show and wine receptions. As in previous years, participants who attend the full day programs on Friday and Saturday will receive complete credit towards renewal of Virginia private pesticide applicators permits. A meeting registration form, a Virginia Vineyards Association membership renewal form, and the complete meeting agenda are appended to this newsletter. Note that the early (cheaper) meeting registration due date is February 1, 2004. Registration increases by $30/person after that date. The Omni Hotel reservation cut-off date is January 19, 2004.

ASEV/ES annual meeting and symposium: Preparations are well underway for Virginia to once again host the Eastern Section meeting of the American Society for Enology and Viticulture (ASEV/ES). The previous Virginia ASEV/ES meeting was in 1995 in Charlottesville and featured an "Alternative Wine Grape Variety" symposium. The 2004 conference will be held 14-16 July at the Hotel Roanoke and Convention Center (www.hotelroanoke.com/). A pre-conference tour of several southwest Virginia wineries is planned for Tuesday, 13 July. The ASEV/ES meeting will include technical presentations, a proposed Viticulture Consortium:East research summit, wine receptions, student paper competition, annual business meeting, and banquet. A highlight of the 2004 meeting will be an integrated symposium entitled "Grapes, wine and environment". The underlying goal of the symposium is to explore how soils, climate (particularly temperature), and cultural practices affect fruit and wine composition and quality, particularly in a warm, humid environment. The program co-chairs, Tony Wolf and Bruce Zoecklein of Virginia Tech, are currently working on program details. Keynote addresses will include discussions by Kees van Leeuwen, of Cheval Blanc (Bordeaux), who holds dual PhD degrees in enology and agronomy, and Erland Happ, winemaker at Happs and Three Hills Winery (www.happs.com.au/pages/family.html) in Western Australia. In addition to soil and climate discussions, the symposium will include current research presentations on vine nitrogen nutrition, including wine issues, and on canopy and crop management practices appropriate for less than ideal wine growing climates. Coming on the heels of the supremely challenging 2003 season, all of these issues are timely and germane to winegrowers throughout the Eastern Section representation.

Mark your calendars now (13-16 July 2004) and visit the ASEV/ES web site (www.nysaes.cornell.edu/fst/asev/) to obtain further details as this exciting meeting draws near.

Vineyard Site Selection bulletin now available: Vineyard Site Selection, Virginia Cooperative Extension Publication #463-020, is now available online. The direct web address is http://www.ext.vt.edu/pubs/viticulture/463-020/463-020.html. A PDF version of the bulletin can be accessed at http://www.ext.vt.edu/pubs/viticulture/463-020/463-020.pdf, however, this will be frustrating without high-speed internet access, as the file is about 11,000 KB in size. The new site selection bulletin represents a synthesis of the last 20 years' experience in grape growing in Virginia, as well as contemporary methods of assessing site suitability. The bulletin includes an in-depth discussion of soil suitability, macro-climate, local climate, and an expanded discussion of biological threats to grape production. This is good stuff, IMHO, and a "must read" for anyone contemplating grape growing in Virginia. Authors are Tony Wolf and John Boyer.

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II. Considerations for dormant pruning (minimizing canker rot infections):

Pruning and wood rotting fungi: A visit to Virginia and Maryland by University of California grape pathologist George Leavitt in May 2003 shed light on some of the pathogens that lurk in our vineyards and that can cause cankers or complete vine death. I was familiar with Eutypa dieback, caused by the fungus Eutypa lata. Avoidance of Eutypa is also covered in the Mid-Atlantic Winegrape Growers Guide, and starts with either double-pruning, or the delaying of dormant pruning until late-winter to reduce the likelihood of wound infection by the Eutypa spores. One of the visual symptoms of Eutypa die-back can be the occurrence of a pie-shaped sector of dead wood in cordons or trunks, when those organs are cut cross-sectionally. However, other wood-rotting fungi can produce a pie-shaped sector of dead tissue. Unless the vine shows the characteristic stunting of shoots and yellowing of leaves (Figure 1) and (http://ohioline.osu.edu/hyg-fact/3000/3203.html) (http://www.ipm.ucdavis.edu/PMG/r302100611.html) the disease may very well not be Eutypa dieback. The wood-rotting lesions caused by Eutypa tend to affect only those shoots that are distal to the lesions (e.g., towards the terminal end of the cordon). Thus, if the infection site is near the junction of the cordon and the trunk, the shoots of the entire cordon may be stunted with yellowed, tattered leaves. If the infection site was near the end of the cordon, only a few shoots may show these symptoms.

In our vineyard visits in Maryland and Virginia in May 2003 we saw very little visual evidence of Eutypa die-back. We did, on the other hand, see a great deal of wood-rotting cankers on older (>10 years old) grapevines. The cankers were almost always associated with old, large pruning wounds, an association that Dr. Leavitt has observed in California and New York State vineyards. Samples of the cankered cordons and trunks were submitted to the Plant Disease clinic at Virginia Tech, and some were examined in Dr. Leavitt's lab at the University of California. The fungus, Botryosphaeria sp. was isolated from both labs. Identification to species is difficult with this genus, but a preliminary identification from the Virginia Tech clinic suggested that the fungus was B. dothidea, which is known to produce canker lesions in a wide range of woody plants. The cankers that we found in grapevine were always associated with old, large (> 3/4") pruning wounds, and typically at the juncture of a spur outlet and the cordon. The wood-rotting fungus tends to affect wood that is proximal to the wound, that is, towards the root system, and the lesion appears elongated; that is, it moves longitudinally faster than it moves radially. Typical cankers observed in the Chardonnay vineyards are shown on cordons in Figures 2 and 3. The incidence of such cankers was fairly high. In vineyards that were more than 10 years old or so, it was not uncommon to find cankers on 25 to 30% of the vines. The cankers in figures 2 and 3 are fairly small. On some vines the cankers had extended well into the trunks and nearly completely girdled the affected trunks. Severely affected trunks were essentially dead and carried no shoots. Thus, the long-term consequence of Botryosphaeria canker is diminished shoot growth and eventual loss of the affected trunk. Pruning out such trunks, and retraining trunks with new shoots is the only management option that can be exercised. I often have growers tell me that they have Eutypa in the vineyard but upon questioning, the grower admits to making that "diagnosis" only on the basis of the pie-shaped lesion of dead tissue observed in cut cordons and trunks. As Dr. Leavitt explained, if the cankers are not associated with shoot stunting, and yellow, tattered leaves distal to the canker, it's probably not Eutypa.

Management of canker diseases: Both Eutypa and Botryosphaeria are slow-moving pathogens and it takes some years to cause loss of a cordon or trunk. But left unchecked, the pathogen will relentlessly cause vascular tissue decay and loss of vine productivity. Whether it's Eutypa or Botryosphaeria ("Bot canker") may not have a practical bearing from a disease management standpoint. It appears that both diseases can start when the causal fungus invades large wounds (as by dormant pruning) during the dormant season. This is one reason why the traditional recommendations for Eutypa die-back avoidance include either double-pruning or delay of making "large" pruning wounds until early spring or even after bud-break.

Eutypa spores are dispersed by wind and rain and their discharge is abundant in winter, decreasing with onset of spring. Systemic infection of vines can occur when spores land on open pruning wounds, and the same holds true of Botryosphaeria spores. In either case, the resulting cankers always migrate from the point of infection downward towards the base of the vine. The diseased trunks can be replaced during dormant pruning if disease is apparent. Affected trunks must be cut well below the point of disease expression (6 inches or more) in order to eliminate the fungus from the vine.

Other than delayed winter pruning, and double-pruning, the other means of reducing the frequency of infection by either Eutypa or Botryosphaeria is to apply a prophylactic fungicide or physical barrier to pruning wounds. Benomyl (e.g., Benlate) in water suspension was previously used as a topical wound treatment to minimize Eutypa infections. Dr. Leavitt indicated that another fungicide, Topsin-M, which is similar in chemistry to benomyl, could also prevent wound infections; however, although Topsin-M is labeled for grape use, the specific use of wound protection is not prescribed on the label. The California researchers looked at other wound-protecting compounds and found that household detergents were effective, but most caused phytotoxicity in the vine during the subsequent growing season. The product called Dreft, a baby laundry detergent, was an exception ‚ it protected wounds without causing vine damage. When painted on fresh pruning wounds at a rate of 1.5 lb per 5 gallons of water, Dreft provided very good protection against all canker diseases. The freshly cut (within hours) wounds would draw up the water/detergent solution and this would provide an effective barrier to subsequent spore germination/growth in the pruning wound. Due to the peculiarities of federal and state laws, when the laundry soap is used in this manner, it's technically a fungicide (pesticide) and must therefore have EPA approval to be used in this fashion. So I can't recommend that Dreft be added to the water that you paint on pruning wounds if you're adding it as a fungicide. If you're adding it to clean the wound surface of dirt and other debris, I don't think there's a problem ‚ you're just a very fastidious grower... I can recommend that you add a little red food coloring (such as Rhodamine red) to the water to see which pruning wounds have been "cleaned." Dr. Leavitt suggested that any pruning wound of a nickel size (3/4") or greater is susceptible to either Eutypa or Bot canker infection.

My research assistant Kay Miller has used a tree wound dressing on large pruning wounds for the last several years in our research vineyard. This may or may not be as effective as the above-mentioned materials, but so far, we have not seen evidence of cankers. It does, however, take some time to paint the product on the wound. If wound protection is not provided and infections occur, cordon or trunk replacement will ultimately be required. You can invest some time during dormant pruning on wound protection, or invest more time (and incur diminished production) later in cordon and trunk renewal. Given the number of older vines that we observed with cankers, I think the argument can be made that wound protection is good insurance.

Other pruning considerations this winter: Recall comments that I made in an earlier newsletter edition this summer that we can expect an increased expression of bud necrosis (BN) this year in association with the poor weather of early summer. This is an imperfect association, but it's pervasive enough that I would spend some time cutting buds NOW, before the pruning is done, particularly with BN-sensitive varieties like Viognier, Riesling and Syrah. We found an unusually high incidence of BN in our Norton as well this season.

Bud necrosis can reduce crop yields in the following season, depending upon the proportion of affected buds. From a dormant pruning standpoint, BN, like cold injury, can be compensated for somewhat by retaining more buds. For example, if one found that 40 to 60% of primary buds were necrotic, then 20 to 40% more buds might be retained at pruning. Unfortunately, it's not so simple to say that the loss of a primary bud will eliminate all crop from that node, so a one-to-one compensation in bud retention to bud loss is not a simple prescription. If the primary bud aborts early in the growing season, secondary (or tertiary) buds may undergo development and may bear a partial crop. We have frequently seen this phenomenon with Viognier. Additional information on BN can be found at the following URL (www.ext.vt.edu/news/periodicals/viticulture/01mayjune/01mayjune.html#I), and in the literature cited therein (I can provide reprints of articles to those interested).

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II. Upcoming events:

January
6 Pruning Workshop at Manatawny Creek Vineyard, Douglassville, PA. 9-noon. Slide show and vineyard demonstration of pruning methods for commercial vineyards. Handouts and coffee are included in the $15 registration fee. Please contact Mark Chien (mlc12@psu.edu) for information and registration or send a check made to Ag Extension.

10 Georgia/South Carolina Wine Grape Conference. Savannah International Trade Center, Savannah, GA. Topics include controlling downy mildew, grape berry moth and phylloxera, and quality wine growing. Contact Gerard Krewer for more information. 229.386.3410.

16 Viticulture session to the Long Island Ag Forum. Shinnecock Building, Room 209. Suffolk Community College. Riverhead, NY. 9 a.m. to noon. Session chair is Ms. Alice Wise, Cornell Cooperative Extension. Topics include weed research update, vineyard weed management, LINY grape research program update, what's new and vine physiology/crop load/ quality. Call 631.727.3595 for information and registration.

26-27 Indiana Winegrowers Guild Symposium. Adams Mark Hotel at the Airport, Indianapolis, IN. Breakout half-day session on Jan 26 - Winery Start Up. Beginner grape grower, wine marketing and wine making. More information at www.indianawines.org/.

27 Wine Grape and Small Fruit Program. Mid-Atlantic Fruit and Vegetable Convention, Hershey, PA. Intermediate viticulture topics include disease control, vine nutrition, weed control, canopy management and vine training. NJ and PA pesticide credits available. Program is sponsored by the State Horticulture Association of Pennsylvania and organized by Rutgers and U Md cooperative extensions. Registration is required. Program information at http://gloucester.rce.rutgers.edu/.

24/25 Viticulture Workshops at Linden Vineyards in Linden, VA.10:30 - 4 :00. These seminars are nuts and bolts sessions for home or professional grape growers. Topics include: Day 1 - site and variety selection, planting, trellis construction, non-bearing vineyard management and economics. Day 2 - controlling weeds, diseases, insects, deer and birds. Jim Law, master wine grower is the instructor. Cost is $75 per person. Space is limited. Lunch is available for purchase. Call 540.364.1997 to register.

27-29 Unified Wine and Grape Symposium. Sacramento Convention Center. Sacramento, CA. One of the largest annual wine industry meetings of the year, Unified features growers and researchers on the program. A huge trade show accompanies the convention. More information is at www.unifiedsymposium.org/

February
7-9 19th Annual Midwest Regional Grape and Wine Conference. Tan-Tar-A Resort in Osage Beach, Missouri. http://mtngrv.smsu.edu/calendar.htm.

7 Pruning and Training Clinic sponsored by Maryland Grape Growers Association. Upper Marlboro Research Center. Call Bob White for details. 410.374.3227.

11 Pennsylvania Association of Winegrowers Annual Meeting. Lancaster, PA. Topic is grape varieties, clones and rootstocks. Tentative Program - speakers include Dr. Peter Cousins, USDA-ARS grape rootstock specialist; Dr. Bruce Reisch, grape breeder at Cornell University, and Ms. Lucie Morton, international viticulture consultant. PAW business meeting is also part of the program. Lancaster Farm and Home Center.

14 Pruning and Training Clinic sponsored by Maryland Grape Growers Association. Rose Vineyard. Damascus. Call Bob White for details. 410.374.3227.

14-15 North Carolina Winegrowers' Association Annual Meeting. Airport Marriott Hotel, Greensboro, NC. General sessions in the morning with concurrent afternoon sessions in viticulture, enology, and marketing.

15-17 Ohio Wine and Grape Short Course in Huron, OH. http://www.ohiowines.org/.

18/19 Ontario Fruit and Vegetable Convention. Grape Session. Brock University, Ste. Catherines, Ontario. Building on Success. A variety of grape topics. Alice Wise, Cornell Cooperative Extension is the featured speaker. Registration is $55 for both days. Call 800.387.3276 for information.

19/21 Virginia Vineyards Association annual Technical Meeting. Omni Hotel, Charlottesville, VA. Information at www.virginiavineyardsassociation.com. Program topics include viticulture, enology and wine marketing.

21 Pruning and Training Clinic sponsored by Maryland Grape Growers Association. University of Maryland Keedysville Research Station. Call Bob White for details. 410.374.3227.

28 53rd Annual Finger Lakes Grape Growers Convention and Trade Show. 8:00 to 4:30 PM, Waterloo Holiday Inn, Waterloo, NY. Contact Finger Lakes Grape Program 315-536-5134 or tem2@cornell.edu. Registration forms will be posted at www.cce.cornell.edu/programs/finger-lakes-grape

March
4/5 The Michigan Wine Industry Annual Meeting will be held March 4/5 at Crystal Mountain Resort in Thompsonville. Registration details will be available on line by January 10, 2004 at www.michiganwines.com or by calling 517 373-1104.

6 Maryland Grape Growers Association Annual Meeting. Howard County Fairgrounds, MD. Theme is Soil Grows Grapes. What Grows the Industry? Visit the MGGA website for more information. http://www.marylandwine.com/mgga/index.html

13 Grape Expectations - A Viticultural and Enological Symposium. Forsgate Country Club in Jamesburg, NJ. Sponsored by Rutgers Cooperative Extension.. Call Gary Pavlis for details.

15-18 Wineries Unlimited. Host Resort. Lancaster, PA. Sponsored by Vineyard and Winery Management. Program features a wide variety of topics on viticulture, enology and wine marketing. Tasting will feature wines from PA, MD and NJ. Dr. Curtis Ellison is expected to be the keynote speaker on matters of wine and health. A large trade show accompanies the meeting. For more information, visit www.vwm-online.com/.

18 New Grape Grower Workshop in association with Wineries Unlimited. Host Resort. Lancaster, PA. This intensive, full-day overview is directed at people who have just started a vineyard or plan to start a commercial vineyard in the Mid-Atlantic regions. It is team taught by Dr. Tony Wolf (VA Tech), Dr. Joe Fiola (U Md) and Mark Chien (Penn State). It covers all topics associated with developing and operating a commercial vineyard.

25 Lake Erie Regional Grape Program Annual Conference. SUNY, Fredonia, NY. http://lenewa.netsync.net/public/lergphom.htm.

April
1-2 33rd Annual Wine Industry Workshop. Ramada Inn, Geneva, NY. Information at http://www.nysaes.cornell.edu/fst/faculty/henick/wiw/

28-29 Pennsylvania Wine Association Annual Meeting. Blair County Convention Center and Courtyard Marriott Hotel. Altoona, PA. Various topics on wine making and marketing and viticulture. http://www.pennsylvaniawine.com/.

June
12 Maryland Grape Growers Association Summer Field Day. Location to be announced.

21-25 Seventh International Symposium on Grapevine Physiology and Biotechnology. UC Davis. Topics include photosynthesis, respiration and carbon relations, water and nutrient relations, stress physiology, temperature responses, cold hardiness physiology, fruit development, genetics and molecular biology. Tentative workshops include climate change and the vine and an update on the International Grape Genome Program. Information at http://grapevinephysiologysymposium.uckac.edu/default.htm.

30-7/2 American Society for Enology and Viticulture National Annual Meeting. Manchester Grand Hyatt Hotel. San Diego, CA. The 2004 Annual Meeting will feature a variety of presentations representing the latest in research in enology and viticulture. The program will also include invited keynote speakers from around the globe. The 55th ASEV Annual Meeting will include a full trade show and enology and viticulture poster sessions. The Annual Meeting includes a special Brett session and will be preceded by a Soil Environment and Vine Nutrition Symposium. http://www.asev.org/.

July
13-15 American Society for Enology and Viticulture Eastern Section Annual Meeting. Roanoke Hotel, Roanoke, VA. Symposium title is "Grapes, Wine and Environment". The focus will be on growing wine in a humid climate with emphasis on soils, mesoclimate and wine production. Technical sessions will feature regional research and projects funded by the Viticulture Consortium. A pre-conference tour of vineyards in southwest Virginia will be offered. http://www.nysaes.cornell.edu/fst/faculty/henick/asev/

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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: vitis@vt.edu

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