North Georgia’s BlackStock Vineyards features a number of innovative adaptations to its growing region, enhancing quality, consistency, and efficiency while integrating key sustainable cultural practices. Forty-two year old owner David Harris, a native of Georgia, is a 1985 Enology and Viticulture graduate of Fresno State and spent the first ten years of his career as a winemaker. During this tenure, Harris made wines from vineyards locations ranging from Oconee County, southeast of Athens, GA to as far northwest as Cartersville, almost to the Alabama/Tennessee line. In November of 1994, galvanized by the maxim that the key to great wine was in the vineyard, Harris left winemaking to develop his own vineyard from the ground up. From experiences and research, Harris’ focus narrowed to an elevation/topography belt from east of Cleveland, GA to west of Dahlonega, GA.

In the spring of ’95, he married Trish Strong, a Director of Operations at TBS in Atlanta. He’d been evaluating prospective vineyard properties for some time and, by the spring of ’96, the couple sold their respective homes and closed on a 90-acre ridge-top property at 1,700-foot elevation in the North Georgia Mountains near Dahlonega.

Harris parlayed the reputation of his string of Gold medal Georgia wines he produced as a winemaker to raising an initial $550,000 of private investment capital into a new LLC. By the spring of ’97, BlackStock’s hills were mechanically planted to 24,000 American Nursery Vinifera grapevines in 6 planting days. Harris’ industry reputation coupled with his research, quickly sparked the development of three other vineyards into the area in as many years. The other owners were not only very supportive of Harris’ efforts, they have quickly developed winery operations, some supplemented by Blackstock grapes. The resulting quality of these winemaking efforts have moved Dahlonega into the spotlight as a destination for Georgia wines.

Harris’ site selection process involved poring over North Georgia soil maps, evaluating 20-year climate records, drilling core soil samples, and collecting temperature data on prospective properties. He discovered that the Blackstock property was in a lower rainfall niche, which rises a dramatic 300 feet from the south and is buffered to the north and west by a mountain range that also forms a barrier to winter cold temperatures. Exceptional airflow dynamics were also evident on the property, an important asset for disease control in the South. Much of the property is well drained and sloping (some fields up to 30%) with critical northeast and northwest exposures. “Matching variety to soil, aspect and slope are primary keys in a successful sustainable vineyard program.” Adds Harris, “it’s remarkable how much disease control, frost prevention and vine mortality issues are addressed at this stage.”

Blackstock’s 40 acres include three clones of Merlot, Viognier (currently the second largest planting in the east), Sangiovese, Touriga, Cabernet, Chardonnay, and Mourvedre. “We’re 70% red and 30% white, banking considerably on the unique Viognier and Touriga. “I’ve been championing these grapes for some time (indeed Harris appeared on the cover of a 1993 Vineyard and Winery Management issue for founding the Viognier Guild, organizing the largest assembly of Viognier wines at that time and organizing the first U.S. symposium on the grape).” Harris quips, “The yields on these grapes are painfully low but the wine quality is high. I’m not sure if my efforts in popularizing Viognier will make me famous or infamous among other growers.”

In the vineyard, Harris bases his planting scheme on the innovative 4WD Antonio Carraro tractor, which at four feet wide and three feet tall delivers 85 horsepower. Independent suspensions between the front and back, keeps all four wheels in firm contact with the ground. “It is the only tractor that can handle our tight planting scheme and this steep terrain. It was originally developed with the steep hillsides of Italy’s Piedmont region in mind, which has more in common with North Georgia than tractors.” Harris adds, “Our red clay hills are quite similar to Italy’s classic “terra rossa” winegrowing soils. Its the tell-tale sign of good drainage. The iron and other metals in the soil oxidize, giving the well-aerated soils their red color, the same way metal oxidizes to red rust.” Indeed, according to The Oxford Companion to Wine, red soils are believed to be beneficial in the vineyard because they are dark enough to absorb needed heat, yet can reflect light at a wavelength that enhances ripening.

The high content of coarse sand and mineral of this granitic-based soil is critical in breaking up the fine clay, enhancing aeration, good texture and tilt he. Two exceptional soil areas in the vineyard are the particularly sandy/silt profile in the Viognier/Mourvedre Rhone block, and a “Tallapoosa Cobbley” in the Cabernet block, which features fist-sized stones mixed with clay throughout the top three feet of the profile. “Deep ripping this soil was like pulling through a rock-tumbler, yet we rarely hit any big rock.” Notes Harris, “This significantly devigorizes our Cabernet, which is much needed with this variety to achieve balance.” The high degree of cobbley stone is readily visible on the soil surface, reminiscent of some of the stony soils of Bordeaux.

A notably unique feature at BSV is its trellis system. This is a divided canopy, vertical shoot positioned system that does what the lyre does, but the Harris-Patterson trellis, named after BSV’s engineer/partner Charlie Patterson, who drafted, constructed and stress-tested what Harris designed, utilizes a much lower bolting point to the post on what is, otherwise, a very top-heavy system. “This has allowed us to use 6 ½ -foot posts without problem, saving in development costs (traditional open-lyre comes with 8 foot post recommendations). The main design goal was to create a fruit zone unobstructed by metal uprights. This allows mechanical cultural practices should future conditions necessitate. We would be able to mechanically prune and harvest without obstruction, which was previously a major concern with Open Lyre.”

With a four-foot minimum cordon height, and three feet of movable catch wires, the trellis stands at seven feet high. The cordon height maximizes air circulation in the fruit zone and provides a height advantage against frost. Harris adds, “Our workers love the 4-foot high fruit-zone that eliminates that little bit of stoop required to work a 3-foot cordon. Since drip tube is also attached at the cordon wire, pickers can maneuver readily under the cordon wire when carrying fruit buckets to centrally located bins. We have had 20 tons of Viognier picked and in refrigeration in 4.5 hours with 15 pickers; that’s good for fruit quality.”

The 9-foot spacing Blackstock has between rows is very tight for a divided canopy, but offers exceptional efficiency. BSV maintains more than the recommended one to one ratio between canopy distance and canopy height, though an overview of the distance between the canopies is close to the look of the meter-by-meter Bordeaux plantings. An aerial view also indicates tremendous efficiency in the percentage of sunlight captured by canopy instead of falling on bare ground. Harris notes, “This also gives us great natural weed suppression under our vines, which minimizes herbicide inputs and costs. We use no pre-emergents and only two low-volume Roundup sprays per year (with some rotation to prevent resistance). We must avoid tillage altogether because that only improves the environment for grape root borer emergence. ” With wet/hot cycles in the south, weed control can be a significant issue, which is why growers avoid divided systems that train vines up and down, limiting air circulation with 7-foot walls of canopy down to the ground and interfering with weed control. Harris’ last point on the 9-foot row spacing, “When the vineyard is 20 years old and the natural devigorization from age occurs, we’ll be able to convert to single canopy, if needed, and be as efficient as other single canopy vineyards our age with 9-foot row spacing.”

“Contrary to some Northeastern literature, we are having no problem with management or equipment access on the 9-foot spacing and divided canopy, of course, this efficiency would not be possible without the right tractor that provides both the accessibility and the safety.” He adds, “In fact, many things seem to have simplified with this system.” One bonus to BSV’s spacing is in advantages to disease management. The spacing between the canopies allows the use of a low-volume Cima sprayer (pronounced cheema) that, along with the great coverage from the close spacing, reduces chemical usage by 35% or more. The Cima, from BDi Machinery, emphasizes a high volume of air that shears a low-volume of water from a venturi nozzle into micronized water droplets. A 50-100 micron droplet covers an exponentially larger surface area than a 300-micron droplet from a conventional air-blast sprayer. But a small droplet is much more susceptible to missing its target with breezes or wind gusts. “Our close spacing allows point-blank spraying and great cross-over into the next canopy, giving exceptional coverage with minimal interference from drift or breeze” notes Harris. The concentrate spraying utilizes just 20-30 gallons per acre. “This simply requires a 100 gallon tank on a three point hitch, maximizing our tank/acre coverage and minimizing our refill time. It also helps tremendously in maneuvering in the tight spacing.” Adds Harris, “We put as much emphasis on our foliar nutrient sprays as we do on fungicides. We integrate micro-nutrient foliar sprays and a minimum of three calcium foliar sprays, which is crucial to structural integrity to the plant including a strong attachment between the berry and the cluster stem, a key area where rot can begin.”

When considering between-vine spacing, Harris refers to Dr. Keith Striegler’s work, formerly from Fresno State and now at the University of Arkansas, that shows the fruit-bearing length of a cordon should not exceed three feet. Beyond that, sugar begins to fall off. “Because of this work, I don’t think I would recommend anyone go over a six-foot spacing between vines,” says Harris. With this apparent channeling of sugars from the terminal end toward the base of the cordons, Harris further compensates by putting an added emphasis on reducing clusters on the last two shoots of the cordon.

So what are the advantages of a 9-foot spaced divided canopy over the more commonly established 10-foot spaced single canopy? Harris responds, “Put simply, we have over 300% more leaves on that acre, with the potential for 70-80% more crop and fewer clusters per shoot. Dividing the canopy doubles the number of leaves per vine, but that’s not all. Devigorizing shoot growth reduces the internode growth (between buds) by half and has another “doubling effect” on the number of leaves. This results in uniform average shoot growth that requires only one hedging, which is cut at about a foot past the top catch wire, giving an average of four feet of canopy. I subscribe to the belief that a balanced crop is more critical to quality than a small crop. When you can spread your crop over a greater number of shoots and cordon length, you naturally achieve a more open canopy and an uncrowded fruit zone, which, again, aides in disease management.” Continues Harris, “This balance gives good cessation of growth late season, which enhances wood, seed, and fruit maturation.

The best system in high vigor situations is divided canopy, bring the vine up and spread it out.” Harris continues, “It’s the key in the Southeast, from Virginia down, I can count on one hand, the number of low vigor/low organic matter vineyard soil sites I’ve seen. We are blessed with fertile soils and a generous climate that gives us vines capable of producing over 400 leaves, rather than 100 leaves. Don’t use devigorizing rootstocks to handicap the vines, use a trellis that will help harness the quality the high vigor can produce. Instead of 10 clusters with 100 leaves, producing 16-18 clusters with 400 leaves in the same area will give you better quality every time. Virginia Tech data shows this, right down to measuring color development and the metabolite glycosyl-glucose which enhances flavor/aroma. Don’t curse the vigor, rejoice in it with the right trellis selection.”

“Our divided canopy completely eliminates overly vigorous ‘bull canes’ which are commonly found in single canopy vineyards. A vineyard that has bull cane problems and requires more than one hedging per season might be a candidate for a trellis or training system change”, says Harris. “We’re seeing a lot of 4-5 year old single canopy-vineyard owners in the Southeast now contemplating training alternatives or additional costs in trellis retrofits to accommodate vigor.” As a further point on excessive hedging, Harris cites recent research that indicates the age of the leaf is critical to fruit ripening, “Excessive hedging means you’re ultimately leaving behind the oldest, most mature leaves. Research shows the most functional leaves are the youngest fully developed leaves, including laterals. A divided system requiring one to two hedging's maximizes the retention of young, functional leaves. The high leaf count of divided canopy also insures that the deleterious effects of leaf-pulling in the fruit zone are minimized.

A pair of John Deere gators, indispensable tools in Harris’ vineyard, relieves the tractor of herbicide spraying and tows the grapes out of the vineyard at harvest. Flotation tires on the gator and harvest trailers prevent soil compaction while executing vineyard operations, a key sustainable practice on otherwise erodible hillsides. During harvest, the gators allow harvesting in virtually any weather condition. “This harvesting versatility is invaluable in delivering quality to the winery. With holes in our buckets, holes in our bins, and all our grapes going into the drying air of refrigeration, the grapes are water-free on delivery. Rescuing those grapes from 2 inches of rain makes our gators the heroes.” Harris successfully tows two standard harvest bins of grapes up any hills of his property. Lange Machinery in Dahlonega, who fabricated the trellis arms, designed the extra-narrow trailers and an electric foot on the trailer that is powered by the gator battery, automatically off-loading the bins. The 42-inch wide bins were sourced from Carson Industries from Glendora, CA and have proven both competitively priced and durable.

As with many East Coast vineyards, BSV maintains a covercrop. “Here, fescue is a tough grass, we allow a natural mix of clover and other minor grass types to promote biodiversity, but we suppress crab grass and bermuda” says Harris, “fescue is drought tolerant and vigorously competitive in wet periods, which helps dry out a soggy soil quickly. It is also crucial to holding the topsoil on our hillsides.” Harris utilizes natural manures and litter to supplement fertilization needs, but limits applications to the winter period to alleviate nitrogen activity.

Blackstock’s IPM program includes monitoring for the grape root borer with pheromone traps and monitoring for the glassy-winged sharpshooter with sticky traps, both through cooperation with Michael Harris, the White County cooperative extension agent. Blackstock actively promotes beneficial insect populations, with the only insecticide use being the occasional July spot-spraying in fields near woodlands to control the migration of Japanese beetles. Imidan is used because of its minimal effect on beneficial insects. Grape root borer emergence prevention is employed through insuring bare, firm ground underneath the vines (95% of emergence occurs within a 30-inch radius of the vine). “They are very susceptible as emerging larvae, and are impeded by dry hard ground and minimizing grass and weed shade. It is important to scout closely for larval casings under the vines to monitor for infestations, but we’ve seen nothing to date” concludes Harris. “However, I did lose a vine to borers that we captured and subsequently identified as an “Apple tree borer”. We’re in the middle of what was an Apple growing belt that runs from Clarkesville to Ellijay, I guess it was a leftover.”

For frost, Blackstock employs two portable Amarillo wind machines and 250 clean-burning double-stack heaters stand at the ready when needed for frost protection. Blackstock is also under-girded by 11,000 feet of subterranean irrigation main lines feeding in-row drip lines. “Irrigation was crucial in our establishment phase, which was aggravated by drought conditions, but had seen only minimal usage until the severe drought conditions of 2002.” Adds Harris “Irrigation will save you tens of thousands of dollars in one year when you really need it. It can also be a valuable management tool in wetting a dry soil in the Spring, to enhance the radiative heat potential of the ground on a frost night.”

BSV also features a new University of Georgia-installed fully automated weather monitoring system that downloads current data to an internet site and can be accessed at Georgiaweather.net and by clicking on Dahlonega. The site has current temperature, highs, lows, wind speed, wind direction, precipitation, humidity, and soil depth temperatures. It is a useful tool in predicting disease pressure to prevent over-spraying, and for winemakers to monitor vineyard conditions from a remote location.