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AGED-612-30 Journal

05/15/07- Spray fungicides

The spray regimen for 2007 will be significantly altered versus that for a typical growing season due to problems associated with the freeze event of April 5 – 9. The freeze completely destroyed the substantial amount of green, growing vine tissue already visible. This necrotic tissue will eventually drop off but will harbor black rot and botrytis spores into the bloom period. It is import to aggressively manage this disease potential through a shorter spray interval and by incorporating a botrytis-specific fungicide such as Vangard into the tank mix. The recent extended dry weather will increase the likelihood of powdery mildew infections- powdery mildew sporulates during the mild, dry conditions typical of May in the Yadkin Valley. The period from now until just after bloom will be critical and growers should be diligent; monitoring weather conditions and leaf wetness to insure fungicides are applied in a timely manner.

05/16/07- Mowing row middles

Managing the vineyard floor may provide additional benefit toward controlling diseases at this critical time. Keeping the row middles mowed relatively close- 3 to 5 inches- will reduce drying time which is crucial to controlling such diseases as downy mildew, which spreads rapidly in warm, moist conditions.

05/17/07 – 05/18/07- Herbicide Vine Rows

Traditionally, vineyard floor management includes maintaining a weed-free strip app 3 ft wide underneath each vine row. Grapevines are poor competitors; young vines in particular may have difficulty during the establishment years if weeds are allowed to grow in the vine rows. A contact or burn-down type of herbicide is used such as Rely (Glyfosinate). Unlike Roundup and its cousins which are systemic in nature, contact herbicides only affect the tissues actually contacted by the chemical. There is no threat of systemic uptake into vine tissues which could kill translocate and kill the vine. While this practice has been around for some time, the trend may be moving away from chemical control of weeds for a number of reasons.

The chemical inputs involved in producing a crop of winegrapes are substantial. Concerns about the cumulative environmental impact over time are legitimate. Also, there is some- perhaps anecdotal- evidence that the constant reapplication of herbicides to the vine rows may eventually render the soil infertile; a concern for the grower as this is of course, the same soil occupied by the vine roots. Among the possible alternatives to chemical weed control are the use of perennial cover crops under the vines that do not compete for nutrients and are small enough to eliminate the need for mowing.

Cabernet Franc prior to herbicide application	Cabernet Franc one week after herbicide application	Cabernet Franc three weeks after herbicide application

05/19/07- Shoot Thinning Time Study

Shoot thinning may be particularly difficult this season due to the effects of the freeze. Vines have responded in one of two ways- shoot growth has been irregular and spotty leaving large unproductive areas on the cordons or vines have produced a plethora of shoots, many of which are not fruitful requiring a significant amount of thinning. Early estimates indicate the crop for 2007 may be reduced by as much as 50 %. The grower faces the difficult economic reality of production costs remaining constant in the face of 50% less income at harvest. Many may attempt to cut corners in an effort to reduce production costs where (if) possible. To obtain an accurate labor cost figure for shoot thinning the 2007 crop, I conducted a time trial in Cabernet Sauvignon vines.

51 vines were thinned in 80 minutes for a rate of 1.57 vines per minute. This was multiplied by 2650- the number of vines in the Medley Meadows vineyard. The projected total time to complete the job is 69.34 hours. Paying a five member crew a rate of $10.00 / hr. the projected labor cost for shoot thinning will be app $700.00.

After evaluating the above time study, I made the decision to hire a crew of 6 for one 9 hour day. Progress was exceptional, however there a 2 acres remaining to be thinned. Since I am currently in a situation where my personal time is available, I have elected to complete the job myself, hopefully in two full days.

As expected, Cabernet Sauvignon sustained the least damage from the freeze. Shoots were of a similar size any quantity as in a normal year. Due to the late bud break associated with Cabernet Sauvignon, and because of the delay in bud break owing to the freeze, I have to wonder if there will be sufficient ripening days before first frost to mature the crop. 

Cabernet Franc responded to the freeze in typical manner- vines produced a large quantity of unfruitful shoots in an effort to produce sufficient foliage for photosynthesis. This is a natural survival mechanism inherent in vinifera that although it helps protect against vines losses, the grower is left with precious little fruit in the current growing season. As stated earlier, this is the dilemma presented by the freeze of 2007- vines still require manual manipulations and spraying, yet theses costs may not be entirely offset due to the drastically reduced crop.

05/23/07- Tying Young Vines / Trellis Repair

In the Cabernet Sauvignon block of Vineyard Two training of young vines continues. These vines were hit particularly hard by the freeze and many require complete renewal up from the graft union. A handful of these vines have finally made it out along the cordon wire but for the most part the 150 or so vines will require yet another developmental season.

Wire staples continue to pop out in Vineyard Two. This is due to the use of an extremely short staple -3/4”- in the establishment phase. As these staples have worked loose they have been replaced by a more substantial 2” staple.

05/25/07- Spray Fungicides

The need for continued applications of fungicides persists. Even though the current drought conditions allow for longer intervals between sprays, nighttime lows in the low 60’s coupled with dry conditions necessitate prevention of powdery mildew infections. I continue to use sulfur as the material of choice for powdery mildew control. While sulfur applications at or above 90 degrees may be risky, with little or no fruit on the vines the fruit burning associated with applying sulfur at higher temperatures is minimized.

05/29/07- Meeting at Westbend Vineyards concerning the freeze event of 2007 and possible courses of action led by Dr. Turner Sutton and Dr. Sara Spayd, both of North Carolina State University

Attended by app 75 vineyard representatives the meeting approached the remainder of the 2007 growing season from two perspectives-

1)      How vineyard spray programs for 2007 will need to be modified

2)      What actions need to be taken during 2007 to facilitate vine recovery and insure their long term survival

Dr. Sutton addressed the need for continued fungicide applications in a program that may include reduced amounts of materials normally required to protect fruit. With many vineyards not cropping at all due to the complete destruction of primary and many secondary buds during the freeze a somewhat less expensive route might be taken dependant as always upon weather conditions.

If the current drought persists, Dr. Sutton suggested stretching the normal 10 day spray interval to 18-20 days. Sulfur and Mancozeb are the materials of choice- inexpensive with no threat of fungal resistance. Growers were reminded to be diligent in monitoring disease pressure as a sudden wet turn with humid nights can cause a virtual explosion of downy mildew. As mancozeb is applied prophylactically, this would possibly require the use of an eradicant material such as prophyt.

Regarding insect control, thrips are present in varying quantities in most vineyards. Damage to fruit can cause splitting and cracking late season. If you tap a cluster and one or two fall out, there should be no problem however, if a handful appears in your palm, control with a material such as Spintor at 6 – 8oz. / acre.

Dr. Spayd spoke to the issue of vine survival even going so far as to say the lack of fruit is the least of our worries. All the vineyards she has visited have some degree of wood damage. Vines may continue to die throughout the growing season as xylem and phloem tissues have both been compromised. Xylem- the water pipe- conducts water and other nutrients upward from the soil while phloem- the food pipe- carries simple sugars back to the roots. To cross section a shoot one would see the pith in the center surrounded by the xylem tubes with the phloem tubes comprising the next layer. Meristematic tissue creates xylem and phloem.

Dr. Spayd observed phloem damage almost immediately after the freeze however xylem damage has only now begun to surface. Shoots may suddenly whither and die and new shoots will be of a markedly different color, appearing pale and yellow instead of the normal healthy deep green. Growers were advised to watch Merlot in particular as this variety is quite sensitive to xylem damage. If one were to cross section a shoot the outer ring of tissue- the phloem, normally green will appear brown. Taking a pocket knife and scraping away the outer layer of bark from the trunk will reveal tissue that is dry, brown and callous if damaged versus the soft, almost cream-like feel of healthy vine tissues. All these problems are exacerbated by the current drought conditions that persist across much of the state.

Vines are already in a depleted, stressed state and the severe water shortage makes their recovery problematic. Young vines with undeveloped root systems which require as much as a gallon of water per day are most susceptible. For non-irrigated vineyards the outlook is grim. While one may be tempted to relieve vine stress with additional soil amendments, Dr. Spayd advised against it. “Whatever you do, do not apply nitrogen- it may speed up the shoot withering that most surely is around the corner if the drought continues. I realize the phosphorus can heel root systems but really, the main nutrient they need now is water”. Dr. Spayd further advised growers against aggressive shoot thinning, preferring that growers leave as much green tissue as possible until the extent of xylem damage is known. Also it is advisable to leave trunk suckers- shoots growing from the bottom of the trunk near the graft union- as this regrowth may be the only thing left with which to renew damaged vines for next season. In the face of these obstacles many are concerned about the lack of crop income for this any possibly subsequent seasons. Debbie Hamrick with the North Carolina Farm Bureau spoke to these concerns.

“There are 47 counties in North Carolina that have been declared disaster areas and may qualify for a portion of the small amount- 1.5 million nationally- of funding available which was approved last week as an add-on the Iraq war spending bill”. Particularly frustrating to many startup vineyards- and many established ones as well- is the stipulation placed on the disbursement of these funds requiring proof of federal crop loss protection insurance in order to qualify. Crop insurance for grapes has been an enigma in North Carolina with virtually no farm insurance agents being aware of it or how to underwrite such policies independently. A short search of the USDA RMA (Risk Management Administration) website confirmed that yes- crop insure is available in 2007 for grapes but offered little practical guidance on how to pursue purchasing it. I plan to call the farm service agency in Stokes County tomorrow.

The infancy of the grape industry in North Carolina and the neophyte nature of many who are interring into this risky endeavor was summarized brilliantly by the following exchange-

Grower- “Was there anything we could have done to prevent this”?

Dr. Spayd- “That’s agriculture; that’s farming. This is the nature of the beast”.

05/30/07- Assess Chardonnay for Wood Damage

Using Dr. Spayd’s methodology for determining the extent of wood damage I started in the Chardonnay block as it was the most severely impacted by the effects of the freeze. The results were discouraging.

As Sara predicted, virtually all vines in the block showed at least some amount of damage to the permanent wood. In the photos the bark has been sliced away with a small knife and the tissue examined for brown outer layers and for a dry, callous texture. In the next series of photos a typical vine in the block is shown, which exhibits large blank areas along the permanent wood or cordon. Since there are several good shoots available near the head of the vine the decision was made to cut off the afflicted cordon with the intention of using one of the good shoots near the head for renewal. I will wait until further into the growing season when these shoots begin to lignify before tying one down to the fruiting wire.

05/31/07- Shoot Positioning, Cabernet Sauvignon

Cabernet Sauvignon currently shows the least damage- I say currently due to Dr. Spayd’s prediction that the current drought would continue to exacerbate the effects of xylem tissue damage. In response I have elected to keep shoot thinning to a minimum, retaining more shoots than normal in the event shoots with xylem damage begin to wither.

A disadvantage of a permanent catch wire system is graphically illustrated here. Since one cannot remove the wires all shoot positioning must be done by hand. Shoot positioning accomplishes several goals, among them gaining maximum sunlight exposure for the developing fruit as well as allowing for sunlight to fall on next years potential fruiting bud locations. Minimal shoot thinning was performed in order to open the canopy for good air flow, thereby lessening disease pressure.

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