Viticulture

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Viticulture (from the Latin word for vine) is the science, production and study of grapes which deals with the series of events that occur in the vineyard. When the grapes are used for winemaking, it is also known as viniculture. It is one branch of the science of horticulture.

While the native territory of Vitis Vinifera is a band of area from Western Europe to the Persian shores of the Caspian Sea, the vine has demonstrated high levels of adaptability and will sometimes mutate to accommodate a new environment after its introduction. Because of this Viticulture can be found on every continent except Antarctica.^[1]

Duties of the viticulturist include: monitoring and controlling pests and diseases, fertilizing, irrigation, canopy management, monitoring fruit development and characteristics, deciding when to harvest and vine pruning during the winter months. Viticulturists are often intimately involved with winemakers, because vineyard management and the resulting grape characteristics, provide the basis from which winemaking can begin.

Contents 1 History 1.1 Roman viticulture 1.2 Medieval viticulture 2 Site Preparation for Vineyards 2.1 Nutrient Content of the Soil 2.2 Physical Composition of the Soil 2.3 Perennial Weed Control 2.4 Erosion Control 2.5 Creating a Weed-Free Zone 2.6 Conclusion 3 Growing vines 3.1 Hazards 4 Green harvest 5 Field blend 6 See also 7 References 8 Further reading 9 External links

[edit] History

The history of viticulture is closely related to the history of wine with evidence of man cultivating wild grapes to make wine dating as far back as the Neolithic period. There is evidence that some of the earliest domestication of Vitis vinifera occurred in the area of the modern day country Georgia.^[2] There is also evidence of grape domestication occurring Near East in the Early Bronze Age around 3200 BC. The ancient Chinese are believed to have made wine from native wild "mountain grapes" like Vitis thunbergii ^[3]

The earliest act of cultivation appears to have been the favoring of Hermaphroditic members of the Vitis Vinifera species over the barren male vines and the female vines which were dependent on having a nearby male to pollinate. With the ability to pollinate itself, over time the hermaphroditic vines were able to sire offspring that was consistently hermaphroditic itself.^[4]

At the end of the 5th century BC, the Greek historian Thucydides wrote:

“

The people of the Mediterranean began to emerge from barbarism when they learnt to cultivate the olive and the vine.[5]

”

The time period that Thucydides was most likely referencing was the time between 3000 BC and 2000 BC when viticulture emerged in force in the areas of Asia Minor, Crete, Greece and the Cycladic Islands of the Aegean Sea. It was during this period that grape cultivation moved from being just an aspect of local consumption to an important component of local economies and trade.^[6]

[edit] Roman viticulture

Between 1200 BC to 900 BC the Phoenician developed viticulture practices that were later utilized in Carthage. Around 500 BC, the Carthaginian writer Mago recorded these practices in 28 volume work that was one of the few artifacts to survive the Roman destruction of Carthage during the Third Punic War. The Roman statesman Cato the Elder was influenced by these text and around 160 BC wrote De Agri Cultura which expounded on Roman viticulture and agriculture.^[7] The Roman writer Columella produced the most detailed work on Roman viticulture with his twelve volume AD 65 text De Re Rustica. Columella work is one of the earliest to detail trellis systems for getting vines off the ground. Columella advocated the use of stakes versus the previously accepted practice of training the vines to grow up along tree trunks. The benefits of using stakes over trees was largely to minimize the dangers associated with climbing trees to prune the dense foliage to give the vines sunlight and later to harvest.^[8]

Roman expansion across Western Europe also brought Roman viticulture to the areas that would be home to some of the world most well known wine-growing regions-the Spanish Rioja, the German Mosel, and the French Bordeaux, Burgundy and Rhône. The Romans were one of the earliest viticulturists to identify steep hillsides as one of the more ideal locations to plant vines because cool air runs downhill and gathers at the bottom of valleys. While some cool air is beneficial, too much can rob the vine of the heat it needs for photosynthesis and in the wintertime increase the hazard for frost.^[9]

[edit] Medieval viticulture

In the Middle Ages, Catholic monks (particularly the Cistercians) were the most prominent viticulturist of the time period. Around this time, an early system of Metayage emerged in France with laborers (Prendeur) working the vineyards under contractual agreements with the landowners (Bailleur). In most cases, the prendeurs were giving flexibility in selecting their crop and developing their own vineyard practice.^[10]

Many of the viticultural practices developed in this time period would become staples of European viticulture till the 18th century. Varietals were studied more intently to see which vines were the most suitable for a particular area. Around this time an early concept of terroir emerged as wines from particular places began to develop a reputation for uniqueness. The concept of pruning for quality over quantity emerged though it would create conflict between the rich landowners who wanted higher quality wines and the peasant laborers who livelihood dependent on the quantity of wine they could sell.^[11] The Riesling is the famous example for higher quality of wine. In 1435 Count John IV. of Katzenelnbogen started this successful tradition^[12].

In Burgundy, the Cistercian monks developed the concept of cru vineyards as homogeneous pieces of land that consistent produces wines each vintage that are similar. In areas like the Côte-d'Or the monks divided the land into separate vineyards, many of which are still around today-like Montrachet and La Romanée.^[13]

[edit] Site Preparation for Vineyards

As the wine and grape industry continue to grow in the United States, it is becoming increasingly important for growers to invest the time and money to properly prepare their vineyard site. There are several major factors an individual should take into account when preparing a successful vineyard site. These factors include, but are not limited to nutrient levels and physical composition of the soil, water drainage capability, perennial weed control and erosion control.

[edit] Nutrient Content of the Soil

The main objective in vineyard nutrition should be to increase and provide the proper nutrient levels to the vine. Chemical properties needing to be controlled in a vineyard are soil pH, organic matter content, nitrogen, phosphorus, potassium, magnesium, zinc and boron levels. To check these levels, soil samples should be taken at two different depths (at 8 and at 16 inches) in an x-shaped pattern across the vineyard. Samples at the same levels should be mixed together, but the different depths should be tested separately. These samples should be taken one year prior to planting (Kurtural et al., 2007). Once the soil requirements have been determined and the grape varieties have been chosen for the site, additions of limestone or sulfur along with fertilizer should be added and deeply plowed or disked into the soil in order to incorporate the additives. Cultivating the soil will also speed up the process of mineralization of the existing organic material (Conradie et al., 1996).

[edit] Physical Composition of the Soil

There are several essential physical properties that need to be identified and controlled on any vineyard site. Sites should have proper drainage, deep soil with no impervious barriers, proper texture, and should be well-aggregated. These factors can be controlled by sub-soiling every two feet along rows and across rows to a depth of 36 inches. Soil compaction is a major limitation to root exploration and can negatively affect yield and plant health. (Hamdeh, 2003) Sub-soiling will systematically break up any barriers present in the soil which will allow for better root penetration and improved water drainage. Drainage tile installation may be necessary in severe instances of poor drainage (Zabadal et al., 1999).

[edit] Perennial Weed Control

A very important factor in vineyard preparation and management is perennial weed control. Herbicides should be applied during site preparation to control the effects of perennial weed species. Examples of these include Johnson grass, thistle, and woody species such as brambles. These weeds can live as budding root stocks and tap roots, along with stolons and as seed. The effects of perennial weed species can create competition between the vine and the weed for vital soil nutrients and water. Herbicides are available for control but must be used with caution so that grapevines are not negatively affected. (Dami et al., 2005) It is important to note that perennial weed control is not a step that occurs only at the onset of site development, but rather is an ongoing process that must be addressed as a normal part of successful vineyard management. Controlling the vineyard floor by limiting the growth of weed species will increase the amount of nutrients available for vine uptake which has been shown to improve berry weight, and vine capacity. (Tesic et al., 2007).

[edit] Erosion Control

In the season before planting, a temporary cover crop should be established. It should be planted in the early spring of the year before and plowed under the soil in late August in order to control erosion and help add organic matter to the soil (Kurtural, 2007). For example, Sudan grass is an excellent choice that offers good weed control and decomposes slowly for improved soil structure. (Schonbeck, 1998) Other cover crop options can be found here.

Usually in the fall, the temporary cover crop is plowed under in preparation for a permanent cover crop. A permanent cover crop is a cover crop that will be maintained in between vine rows and around the vineyard site. This crop will help control soil erosion and help to lessen the compaction that equipment like tractors, harvesters and mowers tend to have on the soil in between the rows allowing for better root exploration. Examples of good permanent cover crop for the eastern United States are perennial rye.

Other forms of erosion control are diversion ditches and standpipes. Diversion ditches lead surface water out of the vineyard from uphill areas. Standpipes are used to drain depression areas. Correcting soil erosion in existing vineyards is usually less effective, more expensive and more difficult than if appropriate measures had been taken in the pre-plant phase of vineyard development (Zabadal, 1999).

[edit] Creating a Weed-Free Zone

The last step in site preparation occurs two weeks before planting when a weed-free zone is created. This involves plowing under strips of the permanent cover crop to allow for the plants to be set. A weed-free area is important because it provides a place for the plants to be located without having to be in immediate competition with weeds.

[edit] Conclusion

Grapevines can be grown in a variety of soil types. In each soil type certain characteristics must be met in order to establish a successful vineyard site. Growers need to properly evaluate and prepare their site well in advance of planting. There are several major factors that a grower should take into consideration when selecting, preparing and maintaining a vineyard site. Some of the most important factors to be taken into account are the nutrient levels and physical composition of the soil, water drainage capability, perennial weed control, erosion control and the creation of a weed free zone.

[edit] Growing vines

The vast majority of the world's wine producing regions are found between the temperate latitudes of 30° and 50° in both hemispheres. In these bands the annual mean temperatures are between 50°F and 68°F. The presence of large bodies of water and mountain ranges can have positive effects on the climate and vines. Nearby lakes and rivers can serve as protection for drastic temperature drops at night by releasing the heat it has stored during the day to warm the vines. The vine needs approximately 1300-1500 hours of sunshine during the growing season and around 27 inches of rainfall throughout the year in order to produce grapes suitable for winemaking. In ideal circumstances the vine will receive most of the rainfall during the winter and spring months. Rain during the harvest time can create many hazards such as fungal diseases and berries splitting. The optimum weather during the growing season is a long, warm summer that allows the grapes the opportunity to fully ripen and develop a balance between the acid and sugar levels in the grape.^[14]

Other factors that viticulturists consider is the topography of the area with hillsides and slopes being preferred over flatter terrain. A main reason for this is that vines on an angle can receive a greater strength of the sun rays with the sunshine falling on a perpendicular angle to the slope. With flatter terrain, the strength of the sunlight is diluted as it is spread out across a wider surface area. An additional benefit is the natural drainage that a slope offers so that the vine doesn't sit with too much moisture in the soil. In cooler climate regions of the northern hemisphere, South facing slopes receive more hours of sunlight and are preferred. In warmer climates, north facing slopes are preferred. (In the southern hemisphere these orientations are reversed).^[15]

[edit] Hazards

See also: List of grape diseases

There are many hazards that a viticulturist needs to be aware of when growing vines. These hazards can have an adverse effect on the wine produced from the grape or kill the vine itself. When the vine is flowering it is very susceptible to weather hazards such as strong winds and hail. Cold temperatures during this period can also bring the onset of millerandage which produces clusters with no seeds and varying sizes. Too much heat can have the opposite reaction and produce Coulure that causes grape clusters to either drop to the ground or not fully develop.^[14]

Viticultural hazards include:

• Oidium
• Frost
• Powdery mildew
• Downy mildew
• Phylloxera
• Plant virus

[edit] Green harvest

A green harvest is the removal of immature grape bunches, typically for the purpose of decreasing yield. In French it is known as a vendange en vert.

Green harvesting is a relatively modern practice most often used to produce fine wine. Removing the tiny, immature grapes while they are still green induces the vine to put all its energy into developing the remaining grapes. In theory this results in better ripening and the development of more numerous and mature flavour compounds. In the absence of a green harvest, a healthy, vigorous vine can produce dilute, unripe grapes.

Many traditionally renowned regions have natural conditions that suppress excess vigor. Examples include the gravelly soil of Bordeaux, the often cool climate of Burgundy, and the meager rainfall of Rioja. In these regions, the vine is prevented from producing too many grapes without human intervention. However, in regions with fertile soil, copious sunlight, and irrigation, the vine can generate huge quantities of characterless grapes. One solution is a green harvest. After fruit set, the quantity of grapes that will result from a vineyard can be estimated. Often the grower has a target yield in mind, measured in tons per acre or hectoliters per hectare. A portion of the grape bunches are cut off, to leave approximately the correct amount.

In Europe, many appellations restrict the yield permitted from a given area, so there is even more incentive to perform green harvesting when presented with excess crop. Often the excess must be sold for a pittance and used for industrial alcohol production rather than wine.

The taste preferences of certain wine tasters such as Robert M. Parker, Jr., have contributed to the producing of wines that is assumed will meet the critic's approval. While the concept of thinning or sacrificing part of the grapes crop, i.e. green harvesting, with the aim of improving the quality of the remaining grapes, predates modern critics, the practice has increased in recent times in vineyards found in California and areas where the grapes grow easily. (McCoy)

[edit] Field blend

A field blend is a wine that is produced from two or more different grape varieties inter planted in the same vineyard. In the days before precise varietal identification, let alone rigorous clonal selection, a vineyard might be planted by taking cuttings from another vineyard and therefore approximately copying its genetic makeup. This meant that one vine could be Zinfandel and the next Carignan. When making wine with little equipment to spare for separate vinification of different varieties, field blends allowed effortless, though inflexible, blending.

Fermentation tanks are now cheap enough that the field blend is an anachronism, and almost all wines are assembled by blending from smaller, individual lots. However, in California some of the oldest (and lowest-yielding) Zinfandel comes from vineyards that are field-blended. Ridge Vineyards owns the Lytton Springs vineyards in Sonoma, which were planted from 1900 to 1905 in what Ridge calls "a traditional field blend of about seventy percent Zinfandel, twenty percent Petite Sirah, and ten percent Grenache and Carignan."

Gemischter Satz is a wine term in German equivalent to a field blend, which means that grapes of different varieties are planted, harvested and vinified together. In older times, this was common, but the practice has almost stopped.

[edit] See also

• Ampelography
• Diurnal temperature variation
• List of vineyard soil types
• Oenology
• Winemaking

[edit] References

[edit] Further reading

[edit] External links

• LIVE - Low Input Viticulture and Enology, Sustainable Viticulture Certification
• AJEV - American Journal of Enology and Viticulture
• Grape Pest Management Guidelines (IPM) UC IPM Online Pest Management Guidelines
• SAFECROP - Proceedings of the 5th International Workshop on Grapevine Downy and Powdery Mildew
• Viticulture and Enology at Washington State University
• [1] - Grape virology program at Washington State University