Viticulture Notes

Vineyard and Winery Information Series:
Vol. 16 No. 6, November - December 2001

Dr. Tony K. Wolf, Viticulture Extension Specialist

Table of Contents

V.Other meetings

I. Current situation:

There's a certain amount of hand-wringing we do when the weather behaves irrationally. Case in point is the unseasonably warm weather that Virginia and much of the mid-Atlantic have experienced this fall. Some have asked if we are staged for a repeat of the vine injury that appeared to result from the rapid drop in temperature on or about 22 November 2000. Daily low temperatures preceding the 22nd were in the mid-twenties, thirties, even forties for the month of November, and many vineyards did not experience their first fall frost until 15 November. Temperatures in some of our monitored vineyards dropped to 15ƒF on 22 November 2000. Injury, particularly to late-maturing varieties such as Cabernet Sauvignon, was widespread. Regrettably, we were not routinely measuring vine cold hardiness in November of last year, and when we commenced in December, vines (here at Winchester) were at expected levels of cold hardiness for that time of year. So I cannot directly relate the swift changes in minimum air temperatures last year to expected cold hardiness. We know, however, that large increases in cold hardiness do not occur until after a defoliating frost. In very simple terms, the combination of time and cold temperatures further increases cold resistance. I suspect that last year's injury was due in part to the very short period of time between the unusually late frost, and the occurrence of temperatures in the teens. In some cases, that interval was only one week.

That was last year. This fall, we've again seen a persistence of warm, autumnal weather. As I finish this letter on 5 December, the temperature had reached 75°F in Winchester. What would happen if the temperature dropped into the teens or single-digits as it did last year? My research technician, Kay Miller, has been routinely assessing bud cold hardiness this fall. Her data suggest that vines are very close to where we would expect them to be at this time of year (Table 1). For example, for Cabernet Sauvignon, clone #7, our prior modeling studies (Pool et al., 1992, and unpublished data) would lead us to predict that our buds should have a MLTE temperature of around +5°F in mid-November, assuming late-October frost. In fact, bud hardiness assessments in mid-November 2001 produced an MLTE temperature of 2°F (Table 1). MLTE (Median Low Temperature Exotherm) temperature is essentially the temperature required to kill about 50% of the buds. In order of increasing hardiness, Viognier, Chardonnay, Cabernet franc, and Traminette were even more cold hardy (Table 1). [See related story on training system comparison]. We had light frosts on 9 and 29 October and 13 November, in each case the temperature reached 28°F. Our measurements of bud cold hardiness give a reasonable estimate of overall vine cold hardiness (Wolf and Cook, 1994), but those measures are not an absolute predictor of cane and trunk hardiness; those organs might sustain injury at a slightly higher temperature. Even with that caveat, I'm confident that our vines can currently withstand temperatures in the teens and high single-digits, if and when we ever see those temperatures. And if we don't, we can start wringing our hands about Pierces Disease...

References:

Pool, et al., 1992. Environmental factors affecting dormant bud cold acclimation of three Vitis cultivars. Proc. 4th Intl Symp. Grapevine Physiol. Turin, Italy, May 1992. pp 611-616.

Wolf, T. K. and M. Kay Cook. 1994. Cold hardiness of dormant buds of grape cultivars: comparison of thermal analysis and field survival. HortScience 29:1453-1455.

Table 1. Dormant bud MLTE temperatures for five varieties grown at AHS Jr. AREC, Winchester as measured during October and November of 2001. The MLTE temperature is essentially the temperature required to kill 50% of dormant buds.

Date	Chardonnay	Cab. Sauvignon	Cab franc	Viognier	Traminette
29 Oct	3.9 F
6 Nov		7.9 F
7 Nov			5.5 F	3.6 F	-2.0 F
13 Nov	0.0 F	1.9 F
21 Nov			-2.6 F	-1.3 F	-8.5 F
27 Nov	-1.3 F

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II. Question from the field

Answer: I realize that the schedule may help some, and confuse others. The specifics of when to spray and what materials to apply are based on vine and pest development, weather conditions, time of last spray, etc. The products that we used during 2001 are listed in Table 2. The season was fairly typical in terms of pest pressure; however, we had higher than normal climbing cutworm problems in the spring due to protracted cool weather after bud swell. This program worked for us, and foliage was clean through harvest (Cabernet Sauvignon was harvested on 29 October). The sulfur application on 27 July did cause some leaf damage, perhaps a function of rate and high temperatures. While Table 2 includes the growth stages for Chardonnay, the same basic program was used for Cabernet and the other varieties grown at our vineyard. The exceptions to that were slight timing differences for the climbing cutworm spray, and the omission of Elevate in varieties not susceptible to Botrytis bunch rot. Our spray program for Norton (Vitis aestivalis) is much different, and typically involves only two fungicide applications, just prior to and just after bloom. I used Tanglefoot adhesive as a physical barrier for climbing cutworms in our Norton planting this year, and it appeared to work, although it is expensive from a material and labor standpoint. Disclaimer: The products and brands listed in Table 2 are listed strictly for informational purposes. Virginia Tech and Virginia Cooperative Extension intend no discrimination against other products that may be equally effective. Readers who are unfamiliar with any of the products listed in Table 2 are encouraged to consult the March-April 2001 Viticulture Notes. For further information about Confirm, see Dr. Doug Pfeiffer's information at http://www.ento.vt.edu/Fruitfiles/VirginiaGrapeSite.html

Table 2. 2001 Pesticide spray program as used at Winchester research vineyard during 2001.

Chardonnay Growth stage/date	Product name	Rate	Target
Buds swollen 13 April	Guthion 50W	2 lb/A	Climbing cutworms
75% budbreak 27 April	Guthion 50W	2 lb/A	Climbing cutworms
8-10" shoot growth 8 May	Penncozeb 75DF Microthiol Disperss (sulfur)	3 lb/A 5 lb/A	BR, DM PM, PHOMP
Pre-bloom 16 May	Penncozeb 75DF Nova 40W Solubor	3 lb/A 5 oz/A 2.5 lb/A	BR, DM BR, PM Boron boost
Pre-bloom 22 May	Ridomil Gold MZ Nova 40 W Solubor	2.5 lb/A 5 oz/A 2.5 lb/A	DM BR, PM Boron boost
Beginning bloom 31 May	Abound	15.4 oz/A	BR, DM, PM
75 % bloom, 7 June
Full bloom/fruit set 12 June	Abound Vangard	15.4 oz/A 10 oz/A	BR, DM, PM Botrytis, PM
BB size berries 22 June	Nova 40W Penncozeb 75DF Imidan 70W	5 oz/A 4 lb/A 2 lb 2 oz/A	PM BR, DM Grape berry moth
Cluster closing 4 July	Penncozeb 75DF Rubigan E.C. Imidan 70W Vangard	4 lb/A 6 oz/A 2 lb 2oz/A 10 oz/A	BR, DM PM GBM, Jap. Beetle Botrytis
17 July	Penncozeb 75DF Rubigan E.C.	4 lb/A 6 oz/A	BR, DM PM
27 July	Microthiol Disperss Confirm DF	6 lb/A 16 oz/A	PM GBM
Pre-veraison, 1 Aug	Abound	15.4 oz/A	DM, PM
Veraison, 14 Aug.	Nova 40W Tenn-Cop 5E Confirm DF Elevate	5 oz/A 3 pints/A 16 oz/A 1 lb/A	PM DM GBM Botrytis
Veraison, 28 Aug.	Nova 40W Tenn-Cop 5E	5 oz/A 3 pints/A	PM DM
Veraison, 1 Sep.	Captan 50W	4 lb/A	DM
Harvest 8 Oct.
Abbreviations: Powdery mildew (PM), Downy mildew (DM), Black rot (BR), Phomopsis cane and leaf spot (Phom), Grape berry moth (GBM).

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III. Research update: Comparison of Traminette, Cabernet Franc, and Viognier under three different training systems

The vineyard was established in 1998 in a statistically appropriate design. Row spacing is 10 feet while vine spacing is at 8 feet for a total of 545 vines per acre equivalent. Varieties are Traminette/own rooted, Traminette grafted to C-3309, Cabernet franc, clone #1, and Viognier, la Jota clone. Cabernet franc and Viognier are grafted to C-3309 rootstock. The rationale for the choice of varieties is as follows: Traminette is a recently released (1996), white-fruited, hybrid cultivar. It has high fruit and wine aroma qualities similar to one of its parents, Gewurztraminer, but possesses much greater cold hardiness and bunch rot resistance than Gewurztraminer does. Preliminary data from our cultivar evaluation at Winchester (our unpublished data), as well as limited commercial experience, suggests that Traminette may be well suited, viticulturally and commercially, to Virginia and other mid-Atlantic states. Our interest in comparing own-rooted and grafted Traminette vines stems from our experience with another vinifera hybrid, Chardonel, which was susceptible to phylloxera vine decline in an earlier cultivar evaluation.

Data collection commenced during the 2000 growing season. Crop yield components from the 2001 season revealed significant variety and training system differences, as might be expected (Table 3). VSP yields (about 2.6 t/a equivalent) on the lightest yielding variety, Viognier, were nearly doubled by either the Smart-Dyson or the Geneva Double Curtain training. Traminette appears to be highly fruitful, and while some of the statistical data of Table 3 were omitted for this newsletter, there was significantly more crop on the grafted vines than on the non-grafted vines. I've also included data that were collected on clusters/shoot in 2001 (Table 3). This is a measure of fruitfulness and it was significantly affected by training system. Again, the specific statistical comparisons are omitted here, but both the GDC and SDY training showed greater clusters/shoot than did the VSP training. That response is likely due to greater sunlight penetration into the renewal region of the canopy with the divided canopy systems (Table 6) GDC training, for example, had 5 to 6 times greater sunlight levels in the fruit zone than did VSP canopies. Fruit rots were minimal during 2001 (Table 4); however, Traminette exhibited about 2% rot severity. Rot etiology was complex: some appeared in response to bird pecking; some appeared due to Botrytis; and some appeared due to late-summer rots such as bitter rot and ripe rot. Fruit chemistry was generally very good (Table 5), with sugar affected by variety but not by training system. Note, however, that we harvested crops at a common Brix level, not at a common date. There were some statistical differences in fruit pH, but these were minimal. Fruit titratable acidity at harvest ranged from 5.8 to 6.7 g/L (data not shown), the highest measured in the VSP.

Besides the yield and fruit quality data, we are also recording the time required to perform routine vineyard activities such as dormant pruning, canopy management and fruit harvest, the goal being to fully understand the economics of the three different systems. Many more years' data, including wine sensory data, will be collected before conclusions are drawn.

Table 3. Crop yield components of three cultivars trained either to Geneva Double Curtain (GDC), Smart-Dyson (SDY), or Vertical Shoot Positioned (VSP) canopies during 2001.

	Crop/vine (lbs)*			Clusters/vine			Clusters/shoot
Cultivar	GDC	SDY	VSP	GDC	SDY	VSP	GDC	SDY	VSP
Traminette/own	27.1	32.3	19.9	92.6	100.3	63.1	1.8	1.8	1.6
Traminette/C-3309	33.5	34.5	21.0	105.8	102.3	67.6	1.9	1.8	1.5
Cab. franc/C-3309	25.9	24.0	13.8	63.6	68.2	35.7	0.9	1.2	0.8
Viognier/C-3309	18.6	19.9	9.7	71.3	80.5	44.8	1.0	1.3	0.9
Significance of main effects and interactions (Pr > F)
Block		ns			ns			ns
Training		0.002			0.002			0.007
Block*Training		ns			ns			ns
Variety		< .0001			< .0001			< .0001
Training*Variety		ns			ns			ns
* Crop/vine multiplied by 0.273 = approximate tons/acre equivalent.

Table 4. Number of rotted clusters/vine and percent rot of varieties trained to Geneva Double Curtain (GDC), Smart-Dyson (SDY), or Vertical Shoot Positioned (VSP) canopies during 2001.

	Rotted clusters/vine (% of total clusters)			Rot severity (%)
Cultivar	GDC	SDY	VSP	GDC	SDY	VSP
Traminette/own	15.5	15.2	16.1	2.3	1.0	1.4
Traminette/C-3309	9.6	1.4	0.5	0.8	0.1	0
Cabernet franc/C-3309	0.2	0	0	0	0	0
Viognier/C-3309	1.0	0.2	0.4	0.1	0	0
Main effects and interactions (Pr > F)
Block		ns			ns
Training (T)		ns			ns
Block*Training (error T)		ns			ns
Variety (V)		<.0001			0.0003
Training*Variety		ns			ns

Table 5. Juice soluble solids, pH and titratable acidity at fruit harvest of three cultivars trained either to Geneva Double Curtain (GDC), Smart-Dyson (SDY), or Vertical Shoot Positioned (VSP) canopies during 2001.

	Soluble solids (°Brix)			pH
Cultivar	GDC	SDY	VSP	GDC	SDY	VSP
Traminette/own	23.6	23.6	23.8	3.22	3.23	3.24
Traminette/C-3309	23.6	24.0	23.4	3.25	3.27	3.29
Cabernet franc/C-3309	22.7	22.6	22.8	3.28	3.26	3.30
Viognier/C-3309	23.7	24.2	24.1	3.33	3.31	3.33
Main effects and interactions (Pr > F)
Block		0.005			ns
Training (T)		ns			ns
Block*Training (error T)		ns			0.01
Variety (V)		0.0004			0.0002
Training*Variety		ns			ns

Table 6. Percent of available light (photosynthetically-active radiation [PAR]) measured in canopies of varieties trained to three different training systems. Training systems were Geneva Double Curtain (GDC), Smart-Dyson (SDY), and Vertical Shoot-Positioned (VSP). As a vertically-divided training system, the SDY consists of an upper and a lower canopy. Data were collected 6 August 2001.

	PAR (% of ambient)
Variety	GDC	SDY, upper	SDY, lower	VSP
Cabernet franc	62.6	15.6	35.7	12.2
Traminette/C-3309	30.2	12.5	18.8	7.4
Traminette/own	59.4	12.8	16.0	10.8
Viognier	29.3	18.4	29.2	12.6

Analysis of variance for sunlight interception data. Figures in bold are significant at level shown.

Source	DF	F	Pr > F
Block	2	0.32	0.7260
Training	3	47.40	< 0.0001
Block*Training	6	0.76	0.6105
Variety	3	7.00	0.0015
Training*variety	9	4.69	0.0012

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IV. VVA Annual Technical Conference: 14-16 February 2002

Plans are being finalized for the annual VVA Technical conference to be held on 14-16 February 2002 at the Omni Charlottesville Hotel, Charlottesville, Virginia. The program will commence with a wine social on Thursday, 14 Feb evening, followed by two full days of technical sessions. A trade show has also been organized. Two principal theme areas of this year's meeting are vine nutrition and vine canopy management. Registration provides entry to technical sessions and trade show, two wine receptions, two lunches, and breaks on Friday and Saturday. The Omni has been a great venue for previous meetings, and is conveniently located on the foot mall in old town Charlottesville. The preliminary program details follow, and a registration form is available (PDF format) Note that the lower advanced registration rate applies to registrations postmarked by 1 February 2002.

Preliminary program details for Virginia Vineyards Association's Annual Technical Meeting, 14-16 February 2002, Omni Charlottesville Hotel, Charlottesville, Virginia. Note: program details are subject to slight change in time and content.

Thursday, 14 Feb
6:00 - 9:00 pm:	Wine reception	Hotel atrium
Friday, 15 Feb
7:00 am - 5:00 pm	General registration	Pre-function area
8:00 am - 7:00 pm	Exhibits open
8:00 - 8:15 am	Tony Wolf, VA Tech Tim Gorman, president VVA	Introductory remarks
8:15 - 8:45 am	Doug Pfeiffer, VA Tech	VA Grape berry moth research updates
8:45 - 9:20 am	Mike Saunders, Penn State University	Modeling GBM development to improve efficacy of control measures
9:20 - 9:50 am	Break
9:50 - 10:20 am	Anton Baudoin, VA Tech	Practical means of reducing powdery mildew resistance to fungicides
10:20 - 10:50 am	Danielle LoGiudice, VA Tech	Reducing crop and berry size with Apogee plant growth regulator
10:50 - 11:50 am	Gordon Murchie, President, VWA	Wine direct shipping issues
12:00 - 1:15	Lunch
1:15 - 1:45 pm	Tony Wolf, VA Tech	Review of grapevine canopy mgt principles, part I
1:45 - 2:15 pm	Andy Reynolds, Brock University	Review of grapevine canopy mgt principles, part II
2:15 - 2:45 pm	Jim Law, Linden Vineyards, Virginia	Canopy management as used at Linden Vineyards, with wine tasting
2:45 - 3:15 pm	Dave Thompson, Bedell Cellars, Long Island	Canopy management as used at Bedell Cellars, with wine tasting
3:15 - 3:45	Break
3:45 - 4:25	Bruce Zoecklein	Enology research updates: use of delestage and micro-oxygenation
4:25 - 5:00 pm	Gary Mainland, University of Arkansas	Adjustment of Norton/Cynthiana acidity, pH and color in the field and in the winery
5:00 - 8:00 pm	Cocktail reception with vendors	Wine reception staged in exhibit hall.
Saturday, 16 Feb
8:00 - 9:00 am	Tony Wolf	Nutrition: Essential elements, deficiency symptoms, plant analysis, and typical means of deficiency avoidance
9:00 - 9:40	Andy Reynolds, Brock Uni., Ontario	Relationship of vine nutrient status to grape and wine quality: towards a definition of terroir
9:40 - 10:20	Greg Evanylo, VA Tech	Benefits of compost to horticultural crops: sources, rates, disease suppression, soil bio activity, etc.
10:20 - 10:50 am	Break
10:50 - 11:30 am	Panel discussion - Al Kellert, Gray Ghost Vineyards - Others TBA	Practical benefits of compost application to vineyards
11:30 am - 12:10 pm	Terry Bates, Cornell University	Vine nutritional studies: soil pH effects on nutrient uptake, K:Mg relationships, nitrogen cycling, and rootstock influences
12:20 - 1:30 pm	Lunch
1:00 - 1:45 pm	Terry Bates, Cornell Uni.	Seasonal distribution of carbohydrates and nutrients in grapevine roots with implications for vineyard management
1:45 - 2:10 pm	Speaker TBA	What constitutes an ideal soil for Virginia vineyards?
2:10 - 3:00 pm	Speaker TBA	Practical means of improving soil drainage
3:00 - 3:30 pm	Break
3:30 - 5:00 pm	Tony Wolf, S. Wescoat, T. Gorman, S. Haskill, Doug Flemer, Al Kellert	VWAB strategic research and extension needs of the Virginia grape and wine industry: moderated by T. Wolf and S. Wescoat. Representation by independent grower, "small" winery and "large" winery, with geo. representation

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V. Other meetings

8 - Basic grape production workshop. Team taught by J. Fiola (U of MD), M. Chien (Penn State), and T. Wolf (VA Tech). Details being developed by Joe Fiola, and course will be presented at the Howard County Fairgrounds, just off I-70 west of Baltimore. Registration details available from Susan: sp178@umail.umd.edu.

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 (mlc12@psu.edu) 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).

February

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 (andy_allen@ncsu.edu).

14 -16 - Annual winter meeting of the Virginia Vineyards Association, Omni Hotel, Charlottesville, VA. Conference will include discussions of vineyard nutrition, disease management, and canopy management, with speakers from New York State, Ontario, Pennsylvania and Virginia. Program details elsewhere in this newsletter. Tony Wolf (vitis@vt.edu).

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.

March

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 (mlc12@psu.edu).

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.vvwm-online.com.

June

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: vitis@vt.edu

Commercial products are named in this publication for informational purposes only. Virginia Cooperative Extension, Virginia Tech, and Virginia State University do not endorse these products and do not intend discrimination against other products that also may be suitable.

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