Viticulture Notes

Vineyard and Winery Information Series:
Vol. 22 No. 2, March - April, 2007

Dr. Tony K. Wolf, Viticulture Extension Specialist, AHS Jr. Agricultural Research and Extension Center
Winchester, Virginia
vitis@vt.edu

Table of Contents

1. Current situation:Easter 2007 freeze
2. 2007 Pest management recommendations
3. Wineries Unlimited and ASEV/ES
4. Vineyard meetings in Virginia
5. Vineyard manager positions available
6. Regional meetings

I Current situation -- Easter 2007 Freeze

The preliminary picture of freeze damage over the Commonwealth from the Easter weekend freeze is sobering. Low temperature predictions by the National Weather Service issued as early as a week ago were generally accurate, although coldest temperatures in many locations occurred either Sunday morning or Monday morning, rather than the forecast Saturday. At this writing (9 April), many areas will still dip below freezing for a 5th consecutive morning on Tuesday the 10th. Conditions through Saturday (7 April) were generally breezy and the advective conditions meant that higher elevations often experienced colder temperatures than did the more sheltered, lower elevations. This is opposite of most of the primarily radiational freeze/frost conditions that we experience in Virginia. The very low temperatures reported on Sunday and Monday mornings appeared to be associated with clear skies and calm winds, when radiational cooling occurs.

The Easter freeze affected a large area, and obviously extended far beyond Virginia into the South and Midwest where grapevines had a headstart on Spring. Low temperatures in a Dahlonega, Georgia area vineyard, where Chardonnay shoots were out about 8 inches, ranged from 20 to 25ºF. Winston-Salem, North Carolina recorded 28º each of three morning, but vineyards west of there in the Yadkin Valley saw temperatures as low as 20º under clear skies on Sunday morning. In Virginia, southern piedmont counties experienced temperatures of 24º, with a low of 28º recorded as far east as our Tidewater AREC in Suffolk, VA. Depending on variety, grapes were at one to several leaves per shoot throughout the central and southern piedmont of Virginia, and out further in North Carolina and Georgia. A preliminary vineyard report from the eastern shore (VA) suggested that frost was avoided there (32º), although our Painter AREC weather station showed 31.5º as a low on Saturday morning. Other vineyard temperatures ranged from low to mid-twenties from Charlottesville area north into Orange County. A Loudoun County vineyard at a somewhat higher elevation reported 20º on Sunday morning. Points further north in Maryland also saw temperatures in the low to mid-twenties; however, grapevines were not as advanced in those locations. Our low here at the AREC in Winchester was 27º, similar to that of our AREC in the Northern Neck. Chardonnay was at full swell to just the start of bud burst here at Winchester.

What can we expect in terms of secondary crop and delayed symptoms of freeze injury? The freeze damage in central and southern piedmont vineyards appears significant. It’s far too early to hazard a guess as to how the freeze will impact the state’s grape crop, but the potential crop was certainly reduced. Other crops such as peaches that were either at or beyond bloom stage were also affected, as were early blooming apples further south. Seasoned grape growers know that secondary buds will eventually break bud and push shoots on the freeze-damaged vines. Temperatures are forecast for the fifties and sixties for this week, so not much growth will occur before next week at the earliest. We know from experience not to expect more than about one-quarter of the primary crop to be borne on secondaries of vinifera varieties, and it may be much less than that. Some hybrids have relatively fruitful secondary buds, however, and will produce appreciable crop from secondary shoots.

I am concerned about the potential for cane and trunk tissue injury where temperatures fell into the low-twenties. If wood injury has also occurred, vines may show continued effects of the Easter freeze for some time, as: poor growth and canopy development during the 2007 season; possible crown gall development on trunks, cordons and canes; unusual development of roots from aerial portions of the vine; and trunk splitting and vine death during or following the 2007-2008 winter. It’s too early to gauge the possible extent of wood injury, but I’d suggest bringing some canes or spurs indoors for 24 to 48 hours and making shallow cuts into the tissue to examine for possible injury. Healthy canes/spurs will have a fairly sharp transition from the corky, brown bark to the green, subtending vascular phloem tissue (Fig. 1, left). Cold injury to the phloem could be expressed as a gradation of browned tissue (Fig. 1, right) from bark to inner xylem tissue. Evidence of this vascular tissue browning does not mean that the vines will not recover. If the vascular cambium is intact, new phloem and xylem tissues may develop; however, development of crown gall or attack by other disease agents or pests may follow. If you find widespread evidence of wood injury, it would be worth training renewal trunks from near the base of vines as insurance in the event that trunks or cordons need to be replaced. The temperatures were borderline for wood injury, and I’m hopeful that wood injury is minor, but it bears mention in this discussion.

Figure1. Normal cane (left) showing healthy phloem and xylem tissues subtending bark. Cane on right has been
exposed to damaging cold and shows evidence of phloem tissue injury as discoloration beneath the brown bark.

The loss or significant reduction in crop will tend to stimulate vegetative vigor. With an absence or paucity of crop, it might be tempting to forego canopy management on affected vines. But remember that next year’s crop (2008) will begin development onthis summer’s (2007) shoots and that bud differentiation is dependent upon good bud sunlight exposure. Don’t allow canopy shade this year to reduce crop for 2008.

If you do have a near-complete loss of crop, you might want to revise your pest management program accordingly. First, be aware that climbing cutworms are still active in some areas, particularly here in northern Virginia. Once the weather warms, as nighttime temperatures remain in the upper forties or warmer, the cutworms will again be at work on remaining primary and developing secondary buds. Cutworms are particularly abundant in vineyards that have leaves, grass clippings, mulch, or other debris on the soil surface. The loss of crop means that a less rigorous grape berry moth, black rot, and botrytis program might be indicated, but stay on top of the mildew program. Powdery mildew might not be quite as insidious with a lack of highly susceptible grape clusters, but don’t let either of the mildews get out of hand on the foliage. To do so will compromise the vine’s ability to tolerate winter (2007-2008) temperatures and will also aggravate disease management in 2008. In response to one email question that arrived this morning, No, there’s no point in spraying fungicides on the damaged shoots. If you have surviving, green tissue, apply protectant fungicides as you normally would (primarily for phomopsis cane and leaf spot at this very early stage). If you have lost all shoots to freeze damage, wait until green growth resumes before commencing your protectant fungicide program.

Again, it’s too early to tell the full extent of the Easter weekend freeze, but the preliminary indications are that a significant crop loss occurred throughout the region. In Virginia, mechanisms for dealing with meteorological disasters, including provisions for lessening the stringency of in-state grape purchase by Virginia farm wineries, may be enabled once the damage is locally assessed and collated by Farm Services Agency (USDA) and local authorities (including Virginia Cooperative Extension). For Virginia producers, I would encourage you to communicate the extent of damage with your local Cooperative Extension office. This will be important as local governments assess the extent of damage to the fruit industry.

II. 2007 Pest Management recommendations

   Virginia Cooperative Extension’s 2007 Grape Pest Management Guide (PMG) can be downloaded at: http://www.ext.vt.edu/pubs/pmg/hf3.pdf
The pesticide recommendations are annually prepared by pest management specialists with grape expertise at Virginia Tech and form the basis of our grape pest management program. Pesticide recommendations augment cultural control practices, including integrated pest management of arthropod pests and good canopy management techniques to set the stage for effective disease control. Detailed disease management recommendations can be found in past issues of Viticulture Notes, available through my website (http://faculty.vaes.vt.edu/vitis), in the Compendium of Grape Diseases (http://www.shopapspress.org/40888.html) and by attending regional vineyard meetings, a number of which are listed in this newsletter. Descriptions of two products that are not listed in the 2007 PMG, but may nevertheless have a place in Virginia vineyards follow:

Aim® herbicide
Jeffrey Derr, department of plant pathology, physiology and weed science, Virginia Tech

Aim is a relatively new herbicide registered for grape production. Two formulations are available, an EC (emulsifiable concentrate), and an EW (emulsion in water). The active ingredient is carfentrazone-ethyl, a contact broadleaf herbicide. Aim causes little to no injury to established grasses, including Kentucky bluegrass, tall fescue, fine fescue, and perennial ryegrass. Hence, Aim has a place for suppression of broadleaf weeds in a grass cover crop. It controls annual broadleaf weeds such as morningglory, pigweed, lambsquarters, and nightshade. Aim will injure certain perennial broadleaf weeds like buckhorn plantain and white clover, but will not provide acceptable control with one application. Annual broadleaf weeds should be treated when small (less than 4 inches tall) for optimum control. Multiple applications or combinations with other herbicides are required for perennial broadleaf weed control. Directed sprays are needed to minimize contact with grape foliage, unless one is interested in burning off suckers. Aim is rapid-acting, with injury to broadleaf weeds seen within 1 to 3 days.                                                                        

Gavel® fungicide
Anton Baudoin, department of plant pathology, physiology and weed science, Virginia Tech

Gavel 75DF, a product from Dow AgroSciences that recently received a supplemental grape label, contains a new chemical mode of action against grape downy mildew. Gavel has been available for use on several vegetable crops for a number of years, and consists of 8.3% zoxamide, the chemical that is new to grapes in the US, plus 66.7% mancozeb which we have long used for grape disease control. Diseases listed on the grape supplemental label are bunch rot, dead arm, and downy mildew. The activity against downy mildew comes from both zoxamide and mancozeb, any activity against other grape diseases (including black rot which is not listed on the label) basically comes from mancozeb only.

Both zoxamide and mancozeb are protectants only, so this is not a product to clean up an existing downy mildew problem; phosphite products or Ridomil would be better in those situations. Recommended spray intervals are 7-10 days, because new growth will not be protected. The preharvest interval for Gavel is 66 days, as it is for mancozeb by itself, so this product will be no help in the mid- to late part of the growing season. The restricted entry interval is 48 hours, as compared to 24 hours for mancozeb by itself.

Gavel’s labeled rate on grapes is 2-2.5 lbs of formulated product per acre, which contains 1.3-1.7 lbs mancozeb (active ingredient). This is something a grower may need to keep track of, because the TOTAL amount of mancozeb allowed, from all sources, including Gavel, Ridomil MZ, and mancozeb-alone products is 3 lbs ACTIVE INGREDIENT per acre for each application, or 19.2 lbs active ingredient per season per acre. The maximum amount of Gavel per season in the eastern US is 8 applications or 15 lbs formulated product per acre. Note that the rate of mancozeb in Gavel is at the low end of that allowed by the mancozeb label itself, and may be somewhat marginal against a disease such as black rot.

It may be good to have a new option with a new mode of action against grape downy mildew, but from what I have seen, it’s not entirely clear whether this product will have much advantage over use of mancozeb by itself at an appropriate rate. It has similar limitations with regard to the time of season that it can be applied, and its protectant-only nature.

Eastern US winegrape fungicide and insecticide guides
VineSmith, Inc. (Jeanette Smith) has an updated 2007 Eastern US Winegrape Fungicide Guide as well as a new Eastern US Winegrape Insecticide Guide available for sale. In VineSmith’s words, these two "at-a-glance" color-coded posters help vineyard managers plan a responsible, effective and economical grape pest management program. In addition to a pest development calendar and the relevant application information and restrictions, the posters cover 30 fungicides and 25 insecticides with information on:

- product chemical and representative trade name (where multiple labels exist)
- manufacturer of representative label
- EPA registration number of representative label
- OMRI (Organic Materials Review Institute) certification for use in organic production

In response to increasing concern over pesticide resistance management, VineSmith has also listed the insecticides and fungicides in order of their mode-of-action class. These classes, known as the FRAC (Fungicide Resistance Action Committee) and IRAC (Insecticide Resistance Action Committee) classes, are identified in the Activity section of the Guides. FRAC and IRAC urge all growers to rotate pesticide applications between these classes and avoid over-using pesticides from a given class, and the Guides provide a logical means for growers to develop a rotational pesticide program. The Guides can be obtained directly from VineSmith Inc. (www.vinesmith.com) (540-869-5188).

III. Wineries Unlimited and the American Society for Enology and Viticulture Eastern Section

Adapted from Mark Chien’s (Pennsylvania State University Cooperative Extension) newsletter, 13 March 2007

Wineries Unlimited is the largest, annual wine and vineyard meeting and trade show in the East and is sponsored by Vineyard and Winery Management (VWM). The Wineries Unlimited venue moved from Lancaster, PA to the Valley Forge Convention Center. The 2007 meeting appeared to be a great success with more room for vendors to spread out and an excellent technical program designed by Richard Leahy.

One new and unique feature of WU this year was a benefit auction for the student scholarship fund of the Eastern Section of the American Society for Enology and Viticulture (ASEV-ES). This was previously done through a casino night. These funds are essential for helping graduate students in viticulture and enology at institutions in the eastern section to continue their studies. These are the people who will be the trained professionals in research and industry who represent the future of our industry (Andy Reynolds, Terry Bates, Tony Wolf, Anna-Katherine Mansfield are a few of the former scholarship winners who are currently engaged in academic programs that support the eastern wine industry).

Rob Merletti of Vineyard and Winery Management had a vision of helping ASEV-ES to fill the void when casino night went away. VWM put forth tremendous effort and resources to develop silent and live auctions during the trade show and at the Best of the East event. Art Carmichael and Mark Basel were the auctioneers and one would be hard pressed to find two more entertaining and persuasive fund-raisers than these two. The audience responded capably by donating almost $16,000 to the scholarship fund.

We are extremely grateful to Rob Merletti and Richard Leahy and the management and staff of VWM for their generosity and just plain hard work and devotion to this benefit auction in its first year. It never would have happened without them, and it promises to get better in years to come. Rob and Richard deserve the gratitude and compliments of everyone in the wine industry. We also appreciate the vendors who generously donated auction items and the successful bidders whose generosity will be turned into checks awarded to scholarship students this July at the ASEV-ES annual meeting at the Holiday Inn in Foglesville, PA from July 14-17. Tony’s note: The ASEV/ES also appreciates the hard work and enthusiasm of Mark Chien (secretary of the ASEV/ES), Ellie Butz, Terry Bates, Bruce Bordelon, Murli Dharmadhikari, Hans Walter-Peterson, and others of the ASEV/ES who helped make the auction a success.

IV. Upcoming vineyard meetings (VA Cooperative Extension and others) in Virginia:

The following vineyard meetings have been scheduled by Virginia Cooperative Extension (VCE) agents Kenner Love, of Rappahannock County VCE, and Michael Lachance, of Nelson County VCE. Meetings occur from 11:00 am until about 2:00 pm at the host vineyard. The first hour will be a tour of the vineyard, followed by a lunch discussion. Everyone is asked to bring a bag lunch. Presentation topics may be modified slightly depending upon unique seasonal issues. One need not register for these meetings and there is no fee to attend. These are good, informal meetings to discuss current topics, meet and talk with fellow growers, and share ideas. In advance, we thank the vineyard owners and management for hosting these meetings.

There are also some commercially-organized meetings of potential interest to readers that will be conducted in Virginia in the coming months.

Three viticulture meetings are being offered by Jason Murray at Chateau O’Brien at Northpoint in Markham, Virginia (Fauquier County) as follows:

- “Disease and pest management in mid-Atlantic vineyards” will be offered on 14 April 2007 (10:00 am to 3:00 pm)
- “Canopy management principles and practices” will be offered on 19 May (10:00 am to 3:00 pm).
- “Grapevine nutrition and late-season canopy management” will be offered on 30 June 2007 (10:00 am to 3:00 pm)

The registration fee for each of Jason’s meetings is $95 per person and includes refreshments, lunch, and wine tasting. Registration and other information can be arranged with Jason Murray at (410) 598-4317, or jason@chateauobrien.com

Jim Law, of Linden Vineyards (Fauquier Co.) has two meetings planned in June.

- “Getting a vineyard started” will be held on 23 June
- “Vineyard Management” will follow on the 24th of June

Each of these meetings will be held at Linden Vineyards from 10:30 a.m. to 4:00 p.m. The cost is $150 per person, per session. See Jim’s website for program details and registration information (http://www.lindenvineyards.com/linden/).

V. Vineyard Manager Positions Available:

Narmada Vineyard in Amissville VA is seeking a vineyard manager. This is a four-year-old vineyard with 10 acres currently planted to hybrid varieties and 5 acres reserved for a suitable red vinifera variety. A winery may be built in the next three to four years. This position is suitable for a self-starting or experienced person who wants to start with a new company and grow as the company grows. Compensation includes a new, fully furnished apartment. Salary is negotiable. If interested, contact: Pandit G. Patil, Phone: 540 937-6613 Fax: 540 937-6643 e-mail: kadgaon@cs.com

Doukenie Winery in Hillsboro, VA is expanding operations, wine production, and retail facilities. We are looking for a Winegrower to help move our winery forward. Current production is 2,500 cases and will grow to 5,000 while maintaining the current quality (raising the quality to the next level). We are looking for a long-term relationship with the new winegrower. Full compensation package available. Interested? Send resume and salary requirements. Call 540-668-9055 Fax 540-668-7679. Email: WinegrowerCandidate@DoukenieWinery.com

VI. Calendar of Regional Viticulture and Enology Events for 2007

This is an expanded listing of vineyard meetings, principally throughout the East, and assembled by Mark Chien of The Pennsylvania State University’s Cooperative Extension.

"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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