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Virginia Cooperative Extension -
 Knowledge for the CommonWealth

Viticulture Notes

Vineyard and Winery Information Series:
Vol. 21 No. 5, September-October 2006

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

Table of Contents

  1. Current Situation
  2. Winchester vineyard 2006 spray program
  3. International workshop on grapevine trunk diseases
  4. Upcoming meetings

I. Current situation

Vintage notes: September and October turned into the two busiest months of my year, which is the principal reason for the tardiness of this VN issue. But there's much to show for the effort with data collected from several on-going projects, two new projects started here at Winchester, and final revisions made to the Wine Grape Production Guide for Eastern North America. Superceding the Mid-Atlantic WineGrape Grower's Guide, this 16-chapter production guide should hit the street around March of 2007. And, of course, we had a harvest to get through, just as most of you did.

Our vineyard visits and volunteered summaries of harvest paint a reasonably favorable picture of harvest grape quality throughout the state, although as in every vintage there were exceptions and disappointments. A very dry and unusually hot July and August led us to hope for a quick, dry harvest. Ernesto dashed that hope at the end of August. September and October experienced repeated showers with 4.9 inches of rain accumulated in September and 3.8 inches in October at the Winchester vineyard. The total amount of rain was not particularly excessive, but the frequency was aggravating -- two steps forward and one step back. Despite the rains, we had many reports of excellent fruit quality and the whites (Chardonnay, Viognier and Traminette) in our own training system block were of very high quality at harvest from the standpoint of flavors and freedom of rot. Late-maturing reds had more of a struggle. Some growers who were not on top of their downy mildew program suffered from the repeated infection periods and favorable weather for downy development. Wildlife, especially birds, hornets, wasps and yellow jackets (we'll call them bees), seemed more problematic this year. We netted our Blackstone variety trial this year and had a good handle on the raccoon problem, but the "bees" took a high toll there. In the end, the 2006 vintage generally illustrated what worked and what hurt in attaining a goal of high fruit quality.

What helped:

What hurt:

Some varieties are more prone to overcropping than are others. We had very good fruit set at Virginia Tech's Blackstone vineyard and managed to grossly overcrop varieties such as Tannat and Mourvedre, both of which had huge clusters (nearly a pound each on average).

None of this should be particularly surprising to seasoned growers; it's just that a challenging vintage season magnifies the problems inherent with less than perfect vineyard management.

There were more "grapes for sale" advertised this year than in past, and the reasons were probably varied. We won't know the total Virginia tonnage of 2006 until the figures are compiled, but my guess is that 2006 may surpass the 5600 tons harvested in 2005. Virginia producers should have received a crop production questionnaire from VDACS within the past several weeks. If not, please contact the Virginia Field Office of the National Agricultural Statistics Service in Richmond (800-899-8566) and ask for the Virginia Grape Production Survey. Your data -- even if your vines are not yet of bearing age -- are important for illustrating industry growth and development and, ultimately, leveraging greater state and local resources for continued support. It makes perfect sense to complete these annual assessments.

There were examples of powdery mildew and downy mildew to be found in the state, but the reasons for outbreaks appeared to be more due to negligence than to possible fungicide resistance issues. That said, we can't afford to relax our resistance management strategies. Pierce's Disease, which has historically been an Eastern Shore and southeast Virginia problem, has moved much further west and north. Surveys done by Virginia Tech researchers in early October revealed positive PD-affected grapevines as far north as Richmond and as far west as Amherst County. Pierce's Disease will be one of the topics on the Virginia Vineyards

Association's winter meeting (8-10 February 2007).

Cooperative Extension in-service training:  Virginia Tech's AHS AREC in Winchester hosted a second viticultural training program for eastern US Cooperative Extension agents on 17 August. This followed a two-day program in August of 2005. Twenty-five extension agents from 7 states (10 from Virginia) attended the August 2006 program, which focused on grape diseases and insect pests and canopy management.  The Virginia Vineyards Association contributed $1,000 in support of Virginia Cooperative Extension agent participation in this program, for which we are most grateful. The agent training programs are part of a regional effort (principal colleagues are Mark Chien from Penn State and Joe Fiola from Maryland) to provide in-depth training to our extension personnel at the county level. We encourage growers and potential growers to consult their local Cooperative Extension office to learn what services they can provide (irrespective of state). The agents with whom we've worked are keen to help and you can help them by asking questions and involving them in your planning and operations. In Virginia, the portal to this information is your local extension office or

II. Winchester vineyard spray program, 2006

A summary of our fungicide and insecticide program used at the AHS AREC vineyard in 2006 is presented in Table 1. Why? As in previous years, this is presented as a record of what we used, with some explanation, and is not intended as an endorsement of specific products. There are many options for an effective spray schedule, and ours is but one. Our program worked and if you gain some positive benefit for your program next year, then it's worth the time to print it. Some considerations: Spray adjuvants are not generally used in our program and most of the products are used at a higher or highest rate when a range of rates is specified on the label. Vines are primarily vinifera (Chardonnay, Cab franc, Cab Sauvignon and Viognier), so an intensive spray program for mildew control is used. Application is with a Durand-Wayland, 3-pt-hitch-mounted air-blast sprayer with application rate of 150 gallons per acre from bloom forward (we will try half that rate per acre in 2007 per Andrew Landers' research and recommendations). We are concerned about mildew resistance to sterol-inhibiting and strobilurin-type fungicides and generally include a modest rate (2 lbs/acre) of sulfur in all sprays with heavier rates (4 to 6 lbs/acre) if sulfur is the sole fungicide for powdery mildew. Rainfall, forecast rain, plant growth stage and systemic or non-systemic nature of material determine our spray frequency.

Table 1. Fungicides and insecticides, and stage of growth at each application, used in the AHS AREC training system vineyard during 2006.


Pesticides used

Growth stage

17 April

Sevin XLR Plus

bud burst

9 May

Penncozeb 75DF, Microthiol Disperss (sulfur)

10" shoots

17 May

Penncozeb 75DF, sulfur

24" shoots

1 June

Pristine, sulfur

beginning of bloom

12 June

Nova 40W, Ridomil Gold MZ, sulfur, Intrepid 2F

bloom -- fruit set

22 June

Penncozeb 75DF, Intrepid 2F, Quintec, sulfur


30 June

Penncozeb 75DF, Elite 45 DF, sulfur, Intrepid 2F, ProPhyt

pea-sized berries

11 July

Sevin XLR Plus

berries hard & green

14 July

Elite 45 DF, sulfur, Assail 30 SG, ProPhyt

berries hard & green

28 July

Elite 45DF, sulfur, ProPhyt, Vangard WG


18 Aug



29 Aug

Quintec, Captan 80WP, Vangard WG


As with previous years, our disease management program was essentially based on a 10-day (±) program in the pre- to immediate post-bloom period, extended somewhat after the first of July. Rainfall during the spray period is shown in Figure 1. Sevin insecticide was applied once at bud-burst due to extensive climbing cutworm activity. The program in May was cheap -- mancozeb and sulfur, with Pristine added at the beginning of bloom (1 June), and again at veraison (18 August). Given our concerns for strobilurin resistance, the two Pristine sprays were our only sprays that contained a strobilurin. We have leaned heavily on the Elite for powdery mildew and black rot, with a total of 3 applications between 30 June and 28 July. To date we have no evidence of powdery resistance to sterol-inhibitors at the vineyard, but we are aware of the potential. Intrepid targeted grape berry moth while Sevin XLR Plus (11 July) and Assail 30 SG (14 July) targeted Japanese beetles. Our last spray on the early varieties and Cabernet franc (Table 1) was on 29 August and included Vangard WG for botrytis bunch rot and captan for a wide range of late-season disease issues. An additional spray of ProPhyt and JMS Stylet oil was made to our Cabernet Sauvignon on 25 September (harvested on 25 October). As with our recommendations to you, we have withheld sulfur application in the 6 weeks prior to harvest to minimize hydrogen sulfide development in wines. Chardonnay harvest commenced on 21 September. Results: Vines were free of our major diseases although we had a very low incidence of non-specific bunch rots develop on Traminette in shaded canopy interiors and a few foliar powdery mildew lesions cropped up in early October but fizzled. Again, this program worked for us. It might not have worked for you under your unique conditions, and it will probably be somewhat different for us next year.

Figure 1. Rainfall (inches/day) at AHS AREC vineyard for period 1 April though 31 August 2006.
Dates shown on horizontal axis are spray dates.

III.  International Workshop on Grapevine Trunk Diseases

Ashley Myers, Grape Pa Viticulture Research/Extension Associate.

I had the fantastic opportunity during the second week of September to attend the 5th International Workshop on Grapevine Trunk Diseases hosted by UC Davis' Department of Plant Pathology. Composed of a group of pioneer researchers, this meeting is held every two-years in countries around the globe to share and debate information regarding grapevine trunk diseases. This year's official topic was "Esca and Grapevine declines" which was later restated as "Esca and related grapevine trunk diseases, whose agents are located in the stem (trunk) of the vine". Approximately 90 people attended from countries including New Zealand, Australia, South Africa, Germany, Turkey, Japan, Italy, Chile, Spain, Mexico, Hungary, Switzerland, and France. Within the United States most attendees were students or faculty of UC Davis; however, three non-Californian Americans were in attendance: Stephen Jordan from Michigan State University, Lucie Morton of Morton Viticulture in Virginia, and me.

figure 1
figure 3
figure 4
   Figure 4
figure 5
figure 6

In 1995, UC Davis plant pathologists began receiving trunk disease samples that at that time were named as Xanthomonas sp. The research has revealed much about the causative agents since then but there is still a long way to go. We have learned that these pathogens can live in the vine very peacefully and we believe they need a trigger for virulence. Our goal now is to figure out that trigger. The biggest obstacle is that these diseases are treated as different diseases all over the world and they may or may not be related to each other.

Grapevine trunk diseases include (but are not limited to) Eutypa dieback, Botryosphaeria canker, Esca, Petri (Young esca) disease, and black foot disease. In Virginia, we have been familiar with Eutypa dieback since 1991 when it was first observed in vineyards. Eutypa is a chronic wood-rotting, fungal disease that is uncommon in young vineyards, appearing when vineyards are over 8-years old. Symptoms are stunted shoots with small, yellowed leaves often cupped downward and possibly appearing tattered (Fig 1). Trunks or cordons below affected shoots will have a canker or dead region of wood surrounding a large pruning wound. A cross-section of affected wood will reveal a wedge of darkened, dead tissue resembling a "pie-shape" (Fig 2). Currently, treatment is approached by removing the infected wood and practicing a multiple-trunking system to compensate for losses. While Eutypa lata is considered to be the primary cause of Eutypa dieback, Michigan researchers have examined another fungus, Eutypella vitis, for grapevine pathogenicity. Results provided evidence that E. vitis is a pathogen of grapevines, causing xylem necrosis and foliar symptoms similar to E. lata. This study also found that cultivars exhibiting resistance to E. lata such as Niagara, Seyval, and Chardonnay may exhibit similar resistance to E. vitis. More information about Eutypa dieback and details on treatment options can be found in the Eutypa dieback disease factsheet on my website (

Botryosphaeria canker ('Bot' canker) was first reported in California in 1987. 'Bot' canker affects spurs, cordons, and trunks causing dieback of the grapevine. The fungus enters through fresh pruning wounds eventually creating a wedge-shaped canker (Fig 3), which is the typical symptom in the earliest stages of the disease and often confused with Eutypa dieback. Perennial cankers grow in the vine for several years causing death of the vine parts. Symptoms seen in Virginia are solely vascular, unlike Eutypa dieback where chlorotic leaves are present, and include cankers, wood streaking, necrotic lesions, and trunk dieback. Like other vascular diseases, symptoms are commonly associated with a stress event. Examinations of Virginia vineyards in 2003, found the 'Bot' fungi associated with vines greater than 10 years of age. At this time, 12 Botryosphaeria species are identified as canker causing. One of the most virulent, B. rhodina is the primary pathogen in California but has not been found in Virginia. Documented species in Virginia include B. dothidea, B. parva, and B. obtusa; B. obtusa is considered the least virulent. In California, the infection distribution of trunk disease pathogens is primarily 'Bot' fungi, followed by Eutypa fungi and Phomopsis viticola. This pathogen distribution was echoed in research from other areas of the world.

Esca and young esca (or Petri disease) are diseases caused by multiple fungal species that obstruct the vascular system of the plant. Petri disease causes decline and dieback of young grapevines, whereas esca is more commonly associated with mature grapevines. Symptoms of esca include shoot and tendril dieback, "tiger-striped" foliage (Fig 4), tyloses and wood streaking (Fig 5), and measles on the grapes. Measles are a symptom more commonly found in table grapes. Esca symptoms can include a white heart rot when the fungus Fomitiporia mediterranea is present. The fungal pathogens of esca are Togninia species (anamorph: Phaeoacremonium)and Phaeomoniella chlamydospora. Anamorph refers to the asexual state of the fungus. At this point only 5 Tognina species have been identified although 24 species of Phaeoacremonium are associated with esca. Old pruning wounds and cracks in the trunk are a source of inoculum with new pruning wounds as the infection site. Spores are released during rainfall and infection occurs during the pruning season. Esca develops slowly in the grapevine until the plant exhibits a sudden apoplectic decline. Petri disease is most commonly associated with Phaeomoniella chlamydospora. Infection by P. chlamydospora resulting in Petri disease is thought to occur in two ways: (1) from infected mother vines into canes, and (2) spore contamination of cuttings during grapevine propagation. Infections can be asymptomatic and may be present in grapevine material prior to planting. Phaeomoniella chlamydospora interferes with xylem function, respiration, and decreases the water potential of the vine. Factors that affect the development of Petri are prolonged hot temperatures, low soil moisture, and over-cropping young vines.

Black foot disease, caused by Cylindrocarpon destructans and Cylindrocarpon macrodidymum, has been shown to be a major cause of young vine death in most areas where grapes are grown. These pathogens affect young vines up to 6 years of age. Foliar symptoms appear as water-stress. Vascular streaking (Fig 6) may occur as a result of gums and tyloses with a brown subcortical zone near roots visible by a cross-section. Feeder roots may have lesions and black goo is often found below the graft. Over watered or J-rooted vines, or vines in compacted soils are more susceptible to black foot development.

The complexity of pathogens associated with each disease is enough to regard any particular trunk disease as a "complex". Adding insult to injury, rarely do we find a single pathogen in a grapevine. One of the questions researchers are currently trying to answer is which is the most important pathogen? With so many pathogens present in pruning wounds and decaying tissue, we need to determine which is actually causing disease and which fungi are secondary invaders. I'll use Phomopsis as an example. Several Virginia growers have asked, "I thought Phomopsis causes cankers too?" The answer is: we don't know. Currently there is a debate about P. viticola's ability to cause cankers. Pathogenicity may depend on cultivar, weather, and other factors. Researchers in South Africa have found numerous P. viticola isolates in internal wood and in pruning wounds. They raise the question, "If it is in pruning wounds why can't it grow deep and cause cankers?" We speculate that the susceptibility of the host is the important factor.

The trellising system has an impact on the number of canker diseases present in vineyards. We see less canker diseases on cane-pruned vines than spur-pruned vines. During cane pruning one cut is made versus dozens and much more old wood is removed, removing more inoculum. The size of the cut makes a difference as well. Larger cuts yield a greater surface area for the fungal spore to land; likewise the number of cuts increases the wound surface area. Rootstocks allowing vigorous growth (and excess nitrogen applications) lead to larger pruning wounds and therefore, more infection.

Clean cultivation is also important in reducing the number of spores in the vineyard. For example, Botryosphaeria fruiting bodies remain on the floor of the vineyard year round if prunings and deadwood are not removed.

Removing infected wood from the vine and the vineyard may be viable treatments of Eutypa dieback and Botryosphaeria if pruning cuts are made 12 or more inches below (proximal) the lesion or point of infection (this may mean removing the entire vine). Burn or bury the 2-year-old or older wood to reduce availability of inoculum in the vineyard. Growers may wish to practice multiple trunk training systems to compensate for trunk losses.

California grape pathologist recommend delaying the timing of large (into 2-year old or older wood) pruning cuts until spring (no earlier than late-March) or using double pruning to remove large sections of vine. Double pruning involves making two cuts to remove the intended portion of the vine. The first cut is made during routine winter pruning 9-bud positions beyond the ultimate point of removal. The vine is then flagged for later attention. At, or around, bud-break a second cut is made to the 2-bud position. With double pruning it is assumed that the first cut may have become infected; however, because the fungi grow slowly the infected portions are removed during the second cut made when inoculum levels are lower. In California, inoculum levels are lower around bud-break because that is the end of their rainy season. In Virginia, however, rain events occur commonly during our main pruning season and inoculum levels may be quite high around bud-break. Therefore, larger cuts may need to be made earlier in the pruning season when inoculum levels are lower. Unfortunately, studies examining the effects of pruning timing and canker disease reduction have not been conducted in the eastern United States. Until they are we can only speculate as to the better option.

Pruning wounds can be treated with an anti-fungal product at the time of cutting which may reduce establishment of trunk pathogens. There are no fungicides registered in the United States for pruning wound treatment. An alternative suggestion is to paint the nickel-size or greater wounds with a soap solution, bathroom (anti-mildew) paint, or tree wound dressing.

With Esca, Petri disease, and black goo the best control tactic is stress reduction. The development of trunk diseases in young vines is generally mitigated by a stress event including water stress, root stress due to bad planting, over-cropping, or undesirable weed control. Anything that restricts the root system may predispose young grapevines to trunk disease. Researchers are examining disease management methods including trunk injection of fungicides, hot water treatment of rootstock cuttings, and soil treatments with anti-fungal compounds.

World-wide, grapevine trunk diseases are annually increasing at a troubling rate. Fortunately, due to the dedication of the researchers present at this conference, our knowledge of trunk diseases is increasing year by year as well. Within Virginia and the eastern United States we are just becoming aware the trunk disease complex. The reason may be that Virginia vineyards are getting older and we see more Eutypa dieback and Botryosphaeria canker, or it may be that we are now learning what to look for (see Either way, trunk diseases are present. Growers need to be aware of the symptoms and methods of prevention because at this time there is no curative control. Virginia Tech's Plant Disease Clinic has the capacity to test grapevines for some of these trunk disease pathogens; however, these pathogens are difficult to detect. Testing information and sample submission procedures are available at:

Additional information about Eutypa dieback and Botryosphaeria canker is available on my homepage at

IV. Upcoming meetings

7 December 2006

What: Grape production primer
When: Thursday, 7 December 2006; 8:00 am - 5:00 pm
Where: Virginia Tech's AHS Jr. Agricultural Research and Extension Center, Winchester, VA

This one-day workshop targets those who are exploring wine grape growing opportunities in the mid-Atlantic region. Topics will include economics, site selection, varieties, and vineyard establishment, including materials and methods. Various aspects of established vineyard management (canopy management, pest management, pruning and training, cold injury avoidance, etc.) will be discussed at an introductory level. Classroom principles will be reinforced with a hands-on review, including dormant pruning principles, in the AHS AREC research vineyard. The workshop will be team-taught by Tony Wolf, Fritz Westover and Ashley Myers (Virginia Tech), Joe Fiola (University of Maryland), and Mark Chien (The Pennsylvania State University).

Information: Tony Wolf, 540-869-2560 x18 ( or Fritz Westover 869-2560 x11 (more information)

10 - 11 January 2007

What: Juice and Wine Analysis Short Course
When: January 10 and 11, 2007
Where: Food Science and Technology department at Virginia Tech, Blacksburg, VA

The Enology-Grape Chemistry Group will offer its annual two-day juice and wine analysis short course on January 10 and 11, 2007. This program will be a hands-on, practically-oriented laboratory course. It will be conducted in the teaching laboratory of the Food Science and Technology Building at Virginia Tech. The program will review: Establishing a winery laboratory, good laboratory practices/HACCP planning/precision and accuracy, fruit processing basics, maturity indices, wine and juice analytical tests, and much more. Registrants will participate in hands-on analysis. Analysis will be supplemented with a laboratory manual and discussions concerning the practical winemaking significance of each test. Enrollment is limited: The short course will be limited to a total of 14 participants. You must register for both days. Registration preference will be given to Virginia bonded winery owners and representatives, and prospective Virginia winery owners who register BEFORE WEDNESDAY, NOVEMBER 8, 2006. After that date, open enrollment will be offered if space is available. Preference will be given to those already in the commercial wine industry. You will not be registered until your check is received.

$450 per person, due by November 8, 2006, checks payable to: Virginia Tech Foundation. On the memo line of your check, please note Juice/Wine SC AND the name of the winery you represent. Mail to: Terry Rakestraw, Department of Food Science & Technology, 25-A FST Bldg., Virginia Tech — 0418; Blacksburg, VA 24061. The course fee is non-refundable.

8 - 10 February 2007

What: Virginia Vineyards Association annual technical conference
When: February 8 -10, 2007
Where: Omni Hotel, Charlottesville VA

Hold the date. Program details are currently being organized. Program will include a new grower/winery section on afternoon of 8th, and two days of advanced technical program to include


To:        Persons interested in starting a commercial vineyard
From:    Shortcourse organizers (T. Wolf, M. Chien, and J. Fiola)
Ref:       Vineyard establishment and operation shortcourse

7 December 2006
AHS Jr. Agricultural Research and Extension Center
Winchester, Virginia

What: This one-day workshop targets those who are exploring wine grape growing opportunities in the mid-Atlantic region. Topics will include economics, site selection, varieties, and vineyard establishment, including materials and methods. Various aspects of established vineyard management (canopy management, pest management, pruning and training, cold injury avoidance, etc.) will be discussed at an introductory level. Classroom principles will be reinforced with a hands-on review, including dormant pruning principles, in the AHS AREC research vineyard. The workshop will be team-taught by Tony Wolf, Fritz Westover and Ashley Myers (Virginia Tech), Joe Fiola (University of Maryland), and Mark Chien (The Pennsylvania State University).

When:  Thursday, 7 December 2006; 8:00 am - 5:00 pm
Where:  AHS, Jr. Agricultural Research and Extension Center, Virginia Tech, Winchester, VA.
Information:   Tony Wolf, 540-869-2560 x18 ( or Fritz Westover 869-2560 x11

Registration: Pre-registration is required and registration is limited to first 60 persons ( registration form): $135 per person, to include morning coffee/danishes, soft-drinks, catered lunch, class materials binder, and to cover our invited speaker expenses. Check to be made payable to "Virginia Tech Foundation", and mailed to "Grapes", Virginia Tech, 595 Laurel Grove Rd. Winchester, VA 22602. Payment must be received by 30 November 2006 to guarantee lunch. Note: This course fills quickly. Registrants are confirmed as registered in the order that registrations are received.

Directions: Virginia Tech's AHS Jr. Agricultural Research and Extension Center (AREC) is located approximately 7 miles southwest of Winchester, VA in Frederick County. From Interstate-81, take the Stephens City exit (exit 307) on the south side of Winchester. Go west into Stephens City (200 yards off of I-81) and proceed straight through traffic light onto Rt 631. Continue west on Rt 631 approximately 3.5 miles. Turn right (north) onto Rt 628 at "T". Go 1.5 miles north on Rt 628 and turn left (west) onto Rt 629. Go 0.8 miles to AREC on left.

Motels: Two suggestions: Holiday Inn Express (540-869-0909) or the Comfort Inn (540-869-6500), both located at I-81 exit # 307 in Stephens City (about 4 miles from the AHS AREC).

"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:

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